This course has been developed under RoNoMar - … course has been developed under RoNoMar -...

This course has been developed under

RoNoMar - Romanian Norwegian

Maritime Project

(2008/111922)

Supported by a grant from Norway through the

Norwegian Cooperation Programme for Economic

Growth and Sustainable Development with Romania.

INSTRUCTOR MANUAL

FIRE PREVENTION AND FIRE FIGHTING

CONSTANTA 2009

TABLE OF CONTENTS INTRODUCTION...........................................................4

Qualification ........................................................................................4 Training ...............................................................................................5 Safety routines ....................................................................................5

Competenta 1 MINIMIZE THE RISK OF FIRE .............6 1.1 CONCEPT AND APPLICATION OF THE FIRE TRIANGLE TO FIRE

AND EXPLOSION.............................................................................................6 1.1.1 Fire components ........................................................................6 1.1.2 Heat ...........................................................................................6 1.1.3 Fuel ............................................................................................7 1.1.4 Oxygen.......................................................................................8 1.1.5 The effects of fire .......................................................................8 1.1.6 Flame, heat and smoke..............................................................8 1.1.7. Gases........................................................................................8

1.2 FLAMMABLE MATERIALS COMMONLY FOUND ON BOARD Flamable material............................................................................................10

1.2.1 Fire classifications....................................................................10 1.3 THE NEED FOR CONSTANT VIGILANCE ....................................12

1.3.1 Fire prevention principle...........................................................12 Competenta 2 MAINTAIN A STATE OF READINESS

TO RESPOND TO EMERGENCY SITUATION INVOLVING FIRES..................................................................................14

2.1. Organization of shipboard fire fighting ...........................................14 2.1.1 General emergency alarm........................................................14 2.1.2 Types of fire alarm systems .....................................................14

2.2 Fire and smoke detection mesures on ships and automatic alarm systems ...........................................................................................................22

2.2.1 Manual Fire System .................................................................22 2.2.2 Heat Detectors .........................................................................23 2.2.3. Smoke Detectors.....................................................................25 2.2.4 Flame-Actuated Detectors .......................................................29 2.2.5 Water-Flow-Actuated Detectors ...............................................31

2.3 ALARM-INDICATING DEVICES.....................................................33 2.3.1. Annunciators ...........................................................................34 2.3.2 Audible Signal Devices ............................................................34 2.3.3 Testing Alarm-Indicating Devices.............................................35 2.3.4 Wiring and Equipment Schematic Diagrams............................35 2.3.5 Indicating circuit faults..............................................................36

2.4 Periodic shipboard drills..................................................................37 2.4.1. Fire drills and on-board training...............................................37

2.4.2 New regulation of the 1974 SOLAS convention. Fire drills and on-board training..........................................................................................38

2.4.3. Minimum standards for on-board fire training and drills ..........39 2.5 Location of fire-fighting appliances and emergency escape routes 41

2.5.1 Ship construction arrangements...............................................41 2.5.2 Materials and fittings used in the construction of 'A' and 'B' class

divisions.......................................................................................................52 Competenta 3 FIGHT AND EXTINGUISH FIRES ......55

3.1 Selection of fire-fighting appliances and equipment .......................55 3.1.1 Portable fire-fighting and dewatering equipment ......................55 3.1.2. Portable fire extinguishers.......................................................55 1. Dry-chemical (powder) extinguishers ............................................55 2. Carbon dioxide fire extinguisher....................................................58 3. AQUEOUS FILM-FORMING FOAM FIRE EXTINGUISHER.........60

3.2. FIRE-FIGHTING TACTICS............................................................61 3.2.1 Fire-fighting strategies..............................................................62 3.2.2 Properties and dynamics of fire................................................62 3.2.3 Dynamics of a fire ....................................................................65 3.2.4 Attack team considerations ......................................................69 3.2.5 Fire attack and hose handling ..................................................74

3.3 esmoking and atmospheric testing .................................................77 3.4. FIRE EXTINGUISHMENT .............................................................79

3.4.1 The removal of fuel ..................................................................79 3.4.2 The removal of heat .................................................................79 3.4.3 The control of oxygen...............................................................80 3.4.4 The reduction of the rate of combustion...................................81 3.4.5 The importance of speed in fire fighting ...................................81 4.3.6. Extinguishing agents ...............................................................81

3.5 USE OF BREATHING APPARATUS FOR FIGHTING fire .............84 3.5.1 Breathing apparatus and protective clothing ............................84 3.5.2 Emergency (oxygen) breathing apparatus ...............................90

3.6 Fire fighting procedure....................................................................92 3.6.1 Basic fire fighting procedures...................................................92 3.6.2 Preventing the spread of fire ....................................................94 3.6.3 Overhauling the fire..................................................................95

3.7 PRECAUTION FOR USE OF FIXES INSTALLATION..................100 3.7.1 Fire main systems..................................................................100 3.7.2 Installed aqueous film-forming foam (AFFF) system..............105 3.7.3 Installed carbon dioxide (CO2) systems .................................110 3.7.4 Halon systems........................................................................123 3.7.5. Aqueous potassium carbonate (APC) ...................................127 3.7.6 Inert Gas Generators .............................................................133

Bibliografie ................................................................137

INTRODUCTION The instructor manual provides guidance on the material that is to be

presented during the manual. The manual material reflects the basic training and instruction for seafarers employed or engaged on board ship as part of the ship's complement specified on Table A-VI/1 -2 of the International Convention on Standards of Training, Certification and Watchkeeping for Seafarers, 1995.

Following the Convention, the material is arranged in three competences: 1. Minimize the risk of fire 2. Maintain a state of readiness to respond to emergency

situations involving fire 3. Fight and extinguish fires

The trainee is not expected to have more than a superficial knowledge of Table A-VI/1 -2 and of SOLAS 74, but even this will be useful for officers as they progress in their sea-going careers and have to take examinations which include fire fighting.

The course outline and timetable provide guidance on the time allocation for the material presentations, but the instructor is free to make adjustments as necessary.

It will be necessary to prepare material for use with overhead projectors or for distribution to trainees as handouts.

Preparation is essential if the manual is to be effective and successful. Throughout the manual it is important to stress that rules and regulations

must be strictly observed and all precautions taken to maximize safety. Where appropriate, trainees should be given advice on the avoidance of accidents.

The detailed teaching syllabus must be studied carefully and lesson plans or lecture notes compiled where appropriate.

Instruction should be made as practical as possible and actual equipment should be used, where available, to illustrate lessons in the classroom.

The theory and practical exercises are similar to the material presented in the Document for Guidance (ref R5), Section 10 Appendix 1. Instructors may find it useful to also refer to this publication and R1, Section B-VI/1.

Qualification Successful completion of this course will enable the seafarer to react in a

correct manner in the event of a shipboard fire, to take appropriate measures for the safety of personnel and of the ship, and to use the fire appliances correctly. They will also be able to state and demonstrate that they have acquired knowledge and skills, which in some instances will enable them to identify and correct defects and prevent fire from occurring.

Practical training utilizes live fire scenarios with real equipment and gear. Training This manual provides training in the basic fundamentals of shipboard fire

fighting, and fire prevention. It meets the training requirements outlined in sections A-VI/1 and Table A-VI/1 of the STCW code, as well as IMO Model 1.20: FIRE PREVENTION AND BASIC FIRE FIGHTING (This manual provides minimum mandatory training in fire prevention and fire fighting and is based on the provision of section A-VI/1-2 of the STCW Code)

Safety routines Safety precautions during drills are a major component in the organisation

of this course. Trainees must be protected from danger at all times while the course is in progress.

Instructors and their assistants must supervise strictly and act as safety guards. When necessary, the staff should wear complete breathing apparatus and carry portable fire extinguishers so that they can assist trainees when required. Other safety precautions include an extra fire hose nozzle, a shower near to the site, first aid equipment and an oxygen unit and resuscitation kit.

COMPETENTA 1 MINIMIZE THE RISK OF FIRE 1.1 CONCEPT AND APPLICATION OF THE FIRE TRIANGLE TO FIRE

AND EXPLOSION Fire is a constant potential hazard aboard ship. You must take all possible

measures to prevent fires from starting. If a fire does start, you must immediately report the fire to the officer of the deck and then extinguish it rapidly. Often a fire will start in conjunction with other damage caused by enemy action, storms, or an accident, Some fires are caused by Hull Maintenance Technicians doing welding, brazing, or cutting. Fires must be extinguished rapidly. Otherwise, they could easily cause more damage than the initial casualty. In fact, a fire could cause the loss of a ship even after the original damage has been repaired or minimized.

As a Damage Controlman, you will need to know a great deal about fires, You need to know how to identify the different classes of fires, how to extinguish them, and how to use and maintain the fire fighting equipment systems and equipment. The more you learn, the more you will be able to contribute effectively to the safety of your ship.

In this chapter, we deal with the fundamentals of fire fighting. These include the nature of fire, the classification of fires, the fundamentals of extinguishment, and the extinguishing agents used.

1.1.1 Fire components Three components are required for a fire. These are a combustible

material, a sufficiently high temperature, and a supply of oxygen. You will hear these components referred to as the fire triangle consisting of fuel, heat, and oxygen (fig. 1-l). Fires are generally controlled and extinguished by eliminating one side of the fire triangle. That is, if you remove either the fuel, heat, or oxygen, you can prevent or extinguish a fire. We will discuss the extinguishment of fires later in this chapter.

1.1.2 Heat Fire is also called burning or combustion. This is a rapid chemical reaction

that releases energy in the form of light and noticeable heat. Most combustion involves rapid OXIDATION. Oxidation is the chemical reaction by which oxygen combines chemically with the elements of the burning substance.

Even when oxidation proceeds slowly, such as a piece of iron rusting, a small amount of heat is generated. However, this heat usually dissipates before

there is any noticeable rise in the temperature of the material being oxidized. With certain types of materials, slow oxidation can turn into fast oxidation (fire) if the heat is not dissipated, These materials are normally stowed in a confined space where the heat of oxidation cannot be dissipated rapidly enough. This is

known as spontaneous combustion. Materials such as rags or papers that are soaked with either animal fats, vegetable fats, paints, or solvents are particularly subject to spontaneous combustion.

For a combustible fuel or substance to catch on fire, it must have an ignition source and be hot enough to burn. The lowest temperature at which a flammable substance gives off vapors that will burn when a flame or spark is applied is known as the FLASH POINT. THE FIRE POINT is the temperature at which the fuel will continue to burn after it has been ignited.

The fire point is usually a few degrees higher than the flash point. The auto-ignition or self-ignition point is the lowest temperature to which a substance must be heated to give off vapors that

will burn without the application of a spark or flame. In other words, the auto-ignition point is the temperature at which spontaneous combustion occurs. The auto-ignition point is usually at a much higher temperature than the fire point.

The range between the smallest and the largest amounts of vapor in a given quantity of air that will burn or explode when ignited is called the flammable range or the explosive range. For example, let us say that a substance has a flammable or explosive range of 1 to 12 percent. This means that either a fire or an explosion can occur if the atmosphere contains more than 1 percent but less than 12 percent of the vapor of this

substance. In general, the percentages referred to in connection with flammable or explosive ranges are percentages by volume.

1.1.3 Fuel One of the components of the fire triangle is fuel. Fuels take on a wide

variety of characteristics. A fuel may be a solid, liquid, or even a vapor. Some of the fuels you will come into contact with are rags, paper, wood, oil, paint,

Figure 1 The fire triangle

Figure 2 The fire square

solvents, and magnesium metals. This is by no means a complete list, but only examples.

1.1.4 Oxygen The air that you breath contains 20.8 percent oxygen. All fires need

oxygen to continue to burn. Some fires will burn with only 6 percent oxygen. However, there are some fires that will produce their own oxygen. Further discussion on oxygen and its association with the control and extinguishment of fires will be covered in the appropriate sections of this chapter.

1.1.5 The effects of fire A burning substance produces a number of chemical reactions. These

reactions produce flames, heat, smoke, and number of gases and other combustion products. The gases and combustion products will reduce the amount of oxygen available for breathing. All of these effects are vitally important to you as a fire fighter. You must be prepared to protect yourself against them.

1.1.6 Flame, heat and smoke Personnel must be protected from the flames, heat, and smoke to avoid

injuries or loss of life. Before you enter a compartment or area where there is a fire, you need to be dressed-out properly.

You will need to tuck your pants into your socks, button the collar on your shirt, and put on a helmet. Wear any other protective clothing prescribed by current directives. If you are a nozzleman or hoseman, you will also need to wear protective gloves and an breathing apparatus (BA) or emergency (oxygen) breathing apparatus (EBA or OBA). The flames and heat from a fire can be intense. However, if you are dressed out properly and maintain adequate distance, you can minimize your chances of getting burned. The smoke will make it hard to see and breath. However, you can cope with these problems by wearing an OBA and a headlamp.

1.1.7. Gases Some of the gases produced by a fire are toxic (poisonous). Other gases

although nontoxic are dangerous in other ways. We will discuss briefly some of the more common gases that are associated with fires.

Carbon Monoxide Carbon monoxide (CO) is produced by a fire when there is not enough

oxygen present for the complete combustion of all of the carbon in the burning material. CO is a colorless, odorless, tasteless, and nonirritating gas. However, it can cause death even in small concentrations. A person who is exposed to a concentration of 1.28 percent CO in air will become unconscious after two or

three breaths. They will probably die in 1 to 3 minutes if left in the area. CO also has a wide explosive range. If CO is mixed with air in the amount of 12.5 to 74 percent by volume, an open flame or even a spark will set off a violent explosion.

Carbon Dioxide Carbon dioxide (CO2) is produced by a fire when there is complete

combustion of all of the carbon in the burning material. CO2 is a colorless and odorless gas. Although CO2 is not poisonous, unconsciousness can result from prolonged exposure at 10 percent volume and higher. Above 11 percent volume, unconsciousness can occur in one minute or less. In a sufficient quantity, death could occur, since CO2 does not provide any oxygen to breathe. The danger of asphyxiation should not be taken lightly; CO2 does not give any warning of its presence, even when it is present in dangerous amounts. It does not support combustion and it does not form explosive mixtures with any substances. Because of these characteristics, CO2 is very useful as a fire extinguishing agent. It is also used for inerting fuel oil tanks, gasoline tanks, and similar spaces.

Hydrogen Sulfide Hydrogen sulfide (H2S) is generated in some fires. It is also produced by

the rotting of foods, cloth, leather, sewage, and other organic materials. H2S can be produced within 6 to 12 hours. Use caution when fighting fires around sewage systems and in spaces where there has been a sewage spill. H2S is a colorless gas that smells like rotten eggs. Air that contains 4.3 to 46 percent H2S is violently explosive in the presence of a flame. H2S is extremely poisonous if breathed, even in concentrations as low as 20 ppm. You may rapidly become unconscious, stop breathing, and possibly die after one breath in an atmosphere that contains 1,000 to 2,000 ppm of H2S.

Hydrogen Chloride Hydrogen chloride (HCl) is emitted by fireretardant paper when the paper

is exposed to temperatures of 93°C (200°F). Also, Flexifloor tile MT 202 exposed to temperatures of 204°C (400°F) will emit HCl. The level of HCl emitted is four times the authorized safe level of 5ppm. Breathing concentrations of 1500ppm is fatal in just a few minutes.

Hydrogen chloride is a colorless, nonflammable gas, which is soluble in water. The gas could be found in a mist form. It is corrosive to the eyes, skin, and mucous membranes. If you have a fire in a compartment where fire-retardant paper or tile is located, be sure to wear an BA or OBA until the compartment is tested and found safe for personnel without an BA or OBA.

Phosphine Phosphine (PH3) is also emitted by fireretardant paper when the paper is

exposed to temperatures of 93°C (200°F). Flexifloor tile MT 202, will also emit PH3 when exposed to temperatures of 2040C (4000F). The level of PH3 emitted is 23 times the authorized safe level of 0.3ppm. Phosphine is a colorless gas that has an odor of decaying fish. It is soluble in water and in organic solvents, and it

ignites at a low temperature. The odor of the gas may be nauseating. When PH3 is suspected, wear an BA or OBA until atmospheric tests show that the area is safe.

1.2 FLAMMABLE MATERIALS COMMONLY FOUND ON BOARD FLAMABLE MATERIAL

1.2.1 Fire classifications Fires are classified according to the nature of the combustibles (or fuels)

involved, as shown in table 1. The classification of any particular fire is of great importance since it

determines the manner in which the fire must be extinguished. Fires are classified as being either class ALFA, class BRAVO, class CHARLIE, or class DELTA fires.

Table 1. Fire Classifications

Class ALFA (A) fires are those that occur in such ordinary combustible

materials as wood, cloth, paper, upholstery, and similar materials. Class A fires are usually extinguished with water, using high or low velocity fog or solid streams. Class A fires leave embers or ashes and must always be overhauled.

Figure 3 Class A fire

Class BRAVO (B) fires are those that occur in the vapor-air mixture over the surface of flammable liquids, such as gasoline, jet-fuels, diesel oil, fuel oil, paints, thinners, solvents, lubricating oils, and greases. Dry chemical (PKP), aqueous film forming foam (AFFF), HaIon 1301, carbon dioxide (CO2), or water fog can be used to extinguish class B fires. The agent you use will depend upon the circumstances of the fire.

Figure 4 Class B fire

Class CHARLIE (C) fires are those which occur in electrical equipment. Nonconducting extinguishing agents, such as PKP, CO2, and Halon 1301 are used to extinguish class C fires. Carbon dioxide and Halon 1301 are preferred because they leave no residue.

Fig. 5. Class C fire

Class DELTA (D) fires occur in combustible metals, such as magnesium, titanium, and sodium. Special techniques have been developed to control this type of fire. If possible, the burning material should be jettisoned overboard. Most class D fires are fought by applying large amounts of water on the burning material to cool it down below its ignition temperature. However, magnesium fires can be smothered by covering the magnesium with lots of dry sand.

Figure 6. Class D fire

1.3 THE NEED FOR CONSTANT VIGILANCE 1.3.1 Fire prevention principle A fire aboard ship may start from an enemy hit, from a cigarette or match

carelessly thrown away, from the spontaneous ignition of various combustible substances, from the use of sparkor flame-producing tools and equipment in an atmosphere containing explosive vapors, from the improper stowage of flammable materials, from static electricity, and from many other causes. As a Damage Control (DC), you have a particular responsibility to prevent fires as well as to fight them.

Damage control patrol watches and division damage control petty officers are required to make regular and frequent inspections as a part of an overall ship's fire prevention program. Such inspections should include the following:

Check to ensure that all installed and portable fire-fighting equipment is in good working order and ready to use if the need arises. Check to ensure that the ship's fire main pressure is adequate at all times. Check to ensure that safe operating procedures are being followed and that personnel are taking all appropriate precautions to prevent fires.

Check to ensure that fire hazards are not allowed to exist. There are so many different kinds of fire hazards that it is almost impossible to list them all. Among other things, keep your eyes open for spilled oil, spilled paint, greasy rags not properly stowed, improper stowage of dangerous materials, and any violation of good housekeeping procedures.

Check to ensure that the ship's fan rooms and ventilation trunks are kept free of cleaning gear, deck gear, and miscellaneous stowage that might restrict

airflow and constitute a fire hazard. Be sure to check ventilation ducts, filters, and heaters at the required intervals. These items continuously collect flammable lint and dirt that could cause a fire to spread rapidly from one compartment to another.

Check continuously for evidence of electrical fire hazards. Report all hazards immediately to the proper authority so that qualified personnel can make repairs or take other corrective action. Some of the electrical hazards to look for are unauthorized plugs or extensions, multiple connectors, and unauthorized wiring. Anything that causes overloading of an electrical circuit is a potential fire hazard. Other fire hazards result from failure to secure electrical devices, distribution equipment, or controls in the approved manner.

Keep a close watch on the conduct of operations that are, by their very nature, likely to present fire hazards. When necessary, see that a fire watch is posted until the conclusion of the hazardous operations. A few (by no means a complete listing) of the shipboard operations that may present special fire hazards are welding or cutting, repairing diesel engines, refueling of the ship, and loading or transferring ammunition. Whenever fuel or ammunition is being transferred, fire hoses and other fire-fighting equipment should be led out and manned to be ready for instant use. When the ship is in port for these operations, both shipboard and shore fire-fighting equipment should be placed where it will be ready for immediate use.

The list of things to be checked and inspected as a means of preventing fires could be extended almost endlessly. Instead of going on with a list, however, it may be more useful at this point to stop and formulate a few general rules for fire prevention:

1. Learn to look at everything with an eye for possible fire hazards. Develop a special kind of alertness for situations or actions that could conceivably lead to a fire.

2. Insist on proper stowage and good housekeeping procedures. Report violations to the proper authority.

3. Maintain all fire-fighting equipment in a state of maximum readiness. While this won't prevent a fire from starting, it is the best possible means of preventing the spread of fire.

4. Make sure that all fire-fighting personnel are trained to be alert to fire-fighting operations.

5. Keep up with new fire-fighting equipment and techniques. The Ship is constantly working to provide improved fire-fighting equipment and improved fire-fighting techniques. It's up to you to keep abreast of new developments in fire fighting and fire prevention.

COMPETENTA 2 MAINTAIN A STATE OF READINESS TO RESPOND TO EMERGENCY SITUATION

INVOLVING FIRES

2.1. ORGANIZATION OF SHIPBOARD FIRE FIGHTING 2.1.1 General emergency alarm All ships are equipped with some type of fire detection and fire alarm

systems. Numerous fire detection and fire alarm systems are in existence today. In this chapter, we will discuss the function and operation of a typical fire detection system and of various fire alarm systems. When you are in charge of the installation or maintenance of either an fire detection or a fire alarm system, you should acquire reference material, such as manufacturer's literature. The purpose of any alarm system is to either protect life of crew. Alarm systems are set up to (1) give early warning so occupants may evacuate the compartment or the ship and (2) notify the commandant soon enough that they have time to react.

2.1.2 Types of fire alarm systems Ships alarm systems is local with base alarm system connections. They is

coded and operate either low-voltage electric power (in general 24V DC). Their characteristics are described in the following paragraphs.

Coded alarm systems A coded alarm system has audible and/or visual alarm signals with

distinctive pulsing or coding to alert occupants to a fire condition and to the location or type of device that originated the alarm. Coding the audible appliances may help personnel to distinguish the fire alarm signal from other audible signals. Clear and early recognition of the signal should encourage a more orderly and disciplined evacuation of the building. A common characteristic of coded alarm systems, especially of selective coded and multiplex coded systems, is that the coded alarm identification provided by the audible alarm signals is not repeated continuously. Normally, after complete repetitions of the coded signal, the coding process ends.

Theory of operation In the event of a fire, a certain sequence of events has to occur for any

alarm system to be effective. First, the fire has to be detected. This can be done

by any of the following means: visually and by operation of manual push-button, heat detectors, water pressure/flow switches flame-actuated detectors or smoke detectors. Any of these devices will initiate a signal to the fire alarm control unit, which is powered by a reliable power supply. (See fig.1 and 2) Second, the control unit accepts the signals from the initiating circuits and, through relays or other circuitry provides the power to operate the indicated devices. These alarm devices may include, but are not limited to, horns, bells, chimes, flashing lights, or annunciations. Finally, operation of the alarm will alert personnel to evacuate and assist fire-fighting personnel in locating the fire, thus protecting life and property.

In the following paragraphs, we will discuss the principle of operation of the associated equipment that makes up an alarm system.

Equipment description Figure 1 shows how the basic parts of a fire alarm system are

interconnected. The devices in the diagram are grouped for convenience in labeling. Physical location and zoning of devices vary for different applications, and many systems do not have all the devices shown.

Figure 1 Alarm device initiates a fire alarm signal

(FCP-Fire Control Panel)

Figure 2 Fire alarm system diagram

Power supplies Source of energy. The source of energy for the alarms referred to in this

paragraph shall be the ‘‘normal source’’. On a system supplied by duplicate storage batteries, the ‘‘normal source’’ shall be construed to mean that part of the supply circuit on the load side of the battery transfer switch and fuses. On a system supplied by a branch circuit the ‘‘normal source’’ shall be construed to mean the load side of any transformer or rectifier employed to modify the nature or magnitude of the supply potential.

Loss of potential. The loss of potential from a supervised normal source of energy automatically shall be indicated at the control unit by the sounding of an audible power failure alarm. The source of energy for the alarm shall be the emergency power source. The source of energy for the alarm of a system supplied by duplicate storage batteries shall be the storage battery being charged.

Ships fire alarm systems operate whit low voltage (24V DC). Regardless of the operating voltage, a system is coded.

Low-voltage alarm systems, especially those provided with battery standby power, are most often found where some form of automatic fire detection or automatic fire extinguishing is connected to the alarm system. However, recent conversion by most alarm system manufacturers to solid-state electronic design, which is essentially a low-voltage direct-current (DC) technology, means that most recent installations are of the low-voltage type.

System Power Supply Power supply refers to the circuitry and components used to convert the

AC line voltage to low-voltage DC for operating the alarm system and for charging standby batteries. If the system is an older one with a dry cell, no rechargeable standby battery, the power supply probably contains a switching arrangement for connecting the battery to the system when AC power fails. Figure 3 is a simplified diagram of a typical DC power supply for powering a low-voltage DC alarm system and for charging a rechargeable standby battery.

Figure 3 Typical DC power supply and battery charge

Transformer T drops the line voltage from 220 volts AC to a voltage in the range of 12 to 24 volts AC. The low AC voltage is rectified by diode bridge D, and the resulting DC voltage powers the alarm system through relay contacts S1 and charges battery B through the current limiting resistor R. When normal AC power is available, energizing relay coil S, contacts S1 are closed. If AC power fails, S1 opens and S2 closes, connecting the battery to the alarm system. Fuse F1 protects against a defect in the power supply or the alarm system during normal AC operation. Fuse F2 protects against alarm circuit defects that would cause a battery overload during DC-powered operation. Removal of resistor R eliminates the battery-charging feature and allows the use of a dry cell battery, which sits idle until AC power fails. At that time, S1 opens and S2 closes, connecting the battery to the alarm system.

There are many variations of this basic power supply design. These variations add such features as voltage regulation, current limiting, and automatic high-rate/low-rate charging, controlled by the state of battery charge. All designs normally provide current and voltage meters, pilot lamps, and switches for manual control of charging rate.

Smoke Detector Power Supply When smoke detectors are used in an alarm system, their internal

electronic circuits are usually powered from the main fire alarm power supply. Some types of smoke detectors have a more strict power supply

requirement than other parts of the fire alarm system, especially with regard to purity of the DC voltage level. The power supply of those smoke detectors must have output voltage regulation and filtering not otherwise required by the fire alarm system. In those cases, the basic power supply may be upgraded to power the smoke detectors as well as the control unit, or a separate smoke detector power supply may be used in addition to the basic supply. In either case, if the system has battery standby, it is usually common to both power supplies.

Control unit The fire alarm control unit provides termination points for all initiating

circuits, indicating circuits and other auxiliary devices. The control unit accepts low current signals from the alarm-initiating circuits and, through relays or other circuitry, provides the larger current required to operate the alarm indicating devices and/or auxiliary devices. The control unit also continuously monitors the condition of the alarm initiating and indicating circuit wiring and provides a trouble indication in the event of an abnormal condition in the system, such as an AC power failure or a wiring failure.

The control unit is usually housed in a sheet metal cabinet (Fig. 4). The control unit usually provides annunciation of signals (telling where a signal originates).

Figure 3 Control unit In Figure 3. is on audio/visual fire-warning device on the bridge and in the

engine control room indicating when and where a fire has occurred. UNITOR provides microprocessor based conventional and addressable

fire detection systems. Both systems have the approval of the major marine classification societies. Comprehensive fault diagnostics and detector condition

monitoring are key features that allow rapid location of faults and minimize down time (Fig. 4 and 5).

Figure 4 Typical conventional fire detection system

Figure 5. Typical addressable fire detection system Alarm Signaling Because of the critical nature of fire alarm systems, a feature known as

"electrical supervision" has been designed into these systems. Alarm systems must be in service at all times; electrical supervision causes a warning (trouble) signal if some potential or actual electrical problem exists in the alarm system.

This trouble signal is clearly distinguishable from a fire alarm signal. Figure 6 shows a typical alarm signaling circuit using electrical supervision.

A continuous small electrical current, supplied by the fire alarm control panel, flows through the series loop formed by one side of the initiating circuit, the end-of-line resistor, and the other side of the initiating circuit as indicated by the arrow. The fire alarm control panel reacts to this constant low current as a no-alarm or normal condition.

Under normal conditions, the alarm and trouble relay coils have the same low value of supervisory current flow. This value is inadequate to close the normally open contacts of the alarm relay. The trouble relay, being more sensitive, is energized by the supervisory current, and the normally closed contacts (TR1) are held open. If the supervisory current drops to zero because of

a broken wire anywhere in the initiating circuit, the trouble relay is de-energized, and the TR1 contacts close, causing an audible and visual trouble signal. Also, the portion of the circuit beyond the broken wire will not operate in the event of an alarm.

If no wires are broken, closing the contacts of an initiating device provides a low-resistance current path, short-circuiting the end-of-line resistor and increasing the alarm relay coil current. The alarm relay is energized, causing its contacts (AR1) to close and the alarm bells to ring. Continued fire alarm operation with a broken wire depends upon the location of the break and which initiating device is actuated.

If, instead of a fire condition occurring, one of the two telephone wires is broken, the supervising current supplied by the transmitter will drop to zero, closing the receiver module relay contacts, lighting the lamp, and sounding the buzzer. The meter indication will be zero, marked on the meter face as "T" (trouble).

Figure 6 Typical alarm signaling circuit If a telephone wire is broken before an alarm condition occurs, the voltage

will be reversed by the alarm transmitter, but the "no current" condition at the alarm receiver will not be changed, and no alarm will be caused. The trouble condition will continue until the broken wire is repaired.

Auxiliary Devices A ship alarm system control unit may have auxiliary contacts that operate

auxiliary functions when an alarm occurs. For auxiliary devices, the power source

can be either the main fire alarm power supply or line power, if battery standby power is not required for the auxiliary functions. A failure of auxiliary functions should not adversely affect the primary function of the alarm system, which is to warn the occupants of a threat of fire.

One auxiliary function included in the majority of fire alarm systems is the heating, ventilation, and air conditioning (HVAC) fan shutdown. Auxiliary contacts are connected into the motor starter circuit for each fan that is to be shut down upon alarm. It may be more convenient to use an alarm voltage output from the control unit to cause fan shutdown. A relay with multiple contacts (a multipole relay) for controlling multiple fans is located near the motor control center or the temperature control panel. The relay coil is energized by alarm voltage from the alarm control unit, causing contacts to open in the individual fan control circuits, thereby stopping all the fans. Other auxiliary devices controlled by the alarm system can perform the following functions: fire door closure, ventilation louver closure, and/or release of extinguishing agent. Consult the manufacturer's literature and/or base blueprints to determine the options included in your fire alarm system.

2.2 FIRE AND SMOKE DETECTION MESURES ON SHIPS AND AUTOMATIC ALARM SYSTEMS

An alarm device initiates a fire alarm signal either as a result of manual

operation, such as a manual fire alarm station, or automatically, as in the case of heat, smoke, flame, or water-flow detectors. Initiating devices, with rare exceptions, have normally open contacts that close on an alarm condition. Normally closed devices are intended only for such applications as operating the shutdown control for fans or other auxiliary devices.

2.2.1 Manual Fire System

Figure 7 shows a remote fire alarm push-button, which is also called a manual pull box, a manual firebox, or a manual fire alarm. A manual fire alarm system may include many initiating devices.

The manual fire alarm devices are to provide a means of manually activating the fire alarm system. They are used in all types of fire alarm systems. They may be the only type of initiating devices provided or they may be used with automatic initiating devices, such

Figure 7 Remote fire alarm push-button

as heat or smoke detectors. Public rooms and engine rooms are examples of such work areas. Single-action and double-action devices are both used. The single-action device requires one action to cause an alarm, and a replaceable glass rod is broken with each operation. The double action device requires two actions to cause an alarm: first, the glass window is broken; second, the alarm lever is pulled. The glass elements in these two examples are necessary parts to retain all the design features. Both devices can be tested without breaking the glass parts by opening the device. To open a manual fire alarm box, you may have to loosen a setscrew or operate a latch with a hexagonal wrench, screwdriver, or key. Manual initiating devices should be visually inspected monthly for physical damage, such as that caused by vandalism or painting. At this time, count the devices to be sure that none have been concealed or removed. Correct deficiencies promptly. Test repaired units by mechanical operation and transmission of local and remote signals without glass breakage. Be sure to inform building and fire department personnel that the test is to be performed. Test all manual devices on a rotation schedule so that all devices are tested semiannually. Some devices should be tested each month, at least one from each initiating circuit (zone) or remote signaling circuit, in the case of coded fire alarm boxes. Keep accurate records of devices tested, their locations, and the rotation scheme. Store a copy of building system diagrams and test records in the control unit.

2.2.2 Heat Detectors Heat detectors are probably the most widely used initiating device for

general-purpose automatic fire alarm systems. Some common types of heat detectors are discussed below.

Heat detectors Figure 8 Figure 9 Figure 10

Low-profile element Replaceable-element Fixed-temp/rate-of-rise heat SPOT TYPE OF FIXED-TEMPERATURE DETECTORS. - Fixed-

temperature heat detectors that are categorized as spot type have a detecting element or elements that respond to temperature conditions at a single point or in a small area.

These detectors are shown in Figures 8 and 9. Other fixed-temperature detectors are manufactured in the style shown in Figure 10.

The spot type of fixed-temperature detectors is used mainly in unattended spaces to detect smoldering fires that increase the temperature of a detector above its design value, usually 135°F to 145°F or 185° to 200°F.

The higher temperature devices are used in spaces that may reach higher temperatures under ordinary conditions, such as boiler rooms, attics, or cooking areas.

The device usually is actuated by the melting or fusing of an element made of a fusible metal alloy. Actuated devices usually can be detected by visual examination.

In the devices shown in Figures 8 and 9, the smaller diameter part in the center drops away. In Figure 10, the dimple becomes a hole when the detector operates.

Fixed-temperature devices are often designed for one-time operation, and the whole device (Figs. 8 and 10) or the element (Fig. 3-9) needs to be replaced.

RATE-COMPENSATED DETECTORS. This type of detector is shown in Figure 11. For low rates of temperature change, rate-compensated detectors operate like fixed-temperature detectors. For higher rates of temperature change, the detector anticipates the rise in temperature to its set point and operates faster than the usual fixed-temperature detector.

It automatically resets and is reusable when the temperature drops below its design value. There is no difference in external appearance between an actuated device and an unactuated device; therefore, its status must be checked electrically.

RATE-OF-RISE DETECTORS. These detectors are found in the styles shown in Figures 7 and 9. Rate-of-rise detectors cause an alarm whenever the rate of temperature rise exceeds about 15°F per minute. Heating causes an increase in air pressure inside the detector. A slow increase in pressure bleeds off through a breather

valve, while a fast increase operates a bellows type of diaphragm, which operates the alarm contact, causing a signal. The detectors automatically reset after actuation and are reusable. Actuation is not visually indicated.

COMBINATION DETECTORS. These detectors are found in the styles of Figures 7 and 9. The combination detectors contain both fixed-temperature and rate-of-rise elements. If either element actuates, an alarm results. The fixed-temperature element is visible and actuates only once. If the fixed-temperature element actuates, the whole device must be replaced. The rate-of-rise element automatically resets and is reusable.

Figure 11. Rate-compensated heat

detector

TESTING HEAT DETECTORS. Test heat detectors semiannually on a rotation schedule to ensure that all devices will be tested over a 5-year period. During the semiannual tests, select at least one detector from each initiating circuit (zone) for testing. Nonreusable detectors with replaceable elements can be tested by removing and reinstalling the element. Test and replace all nonreusable detectors in a 5-year period. The testing provides training opportunities and improves the alarm system reliability.

Keep accurate records of devices tested, their locations, and the rotation scheme so no devices are overlooked and so that other personnel can do the testing.

The spot type of heat-actuated detectors can be tested using various sources of heat. If the detector is located in a hazardous area that may contain explosive fumes or other highly flammable materials, use an explosion proof lamp. For nonhazardous areas, the heat source may be an infrared lamp, a hair dryer, or a hot-air gun. Be careful to avoid heat or smoke damage to reusable detectors and to the surroundings.

To test combination detectors that have a nonreuseable fixed-temperature element, test both the rate-of-rise and fixed-temperature features. First, use a higher heat level for a short period and direct it away from the fusible fixed-temperature element, if possible, to actuate only the rate-of-rise element. When an alarm occurs, allow cooling; reset; and then apply more gradual heat to actuate the fixed-temperature element.

2.2.3. Smoke Detectors Smoke detectors are faster acting than heat detectors. They are frequently

used in fast-acting automatic fire detection systems that incorporate an extinguishing agent release function to protect high value or highly combustible storage and work areas. Computer rooms, aircraft storage and repair areas, explosive processing areas, and telephone equipment rooms are frequently protected in this way.

Smoke-actuated detectors may be of the photoelectric type used in spot, beam, or duct designs or the ionization type, which is applied in the spot or duct design. The principle of operation is the same, regardless of design.

PHOTOELECTRIC SMOKE DETECTORS. Most modern photoelectric detectors of the spot type use the light-reflection principle to detect smoke. The diagram in Figure 12 shows a typical arrangement of functional parts. A pulsed light beam from a light-emitting diode (LED) with its associated optics is projected across the interior of a blackened chamber that may contain smoke to be detected. A photocell, with its optics, looks toward the projected beam along a line perpendicular to the beam. When smoke enters the chamber, the smoke particles reflect a small portion of the light beam toward the photocell, which provides a voltage to be amplified and causes an alarm. The light source may be monitored ahead of the smoke chamber and regulated to prevent variation of the light intensity from causing erratic detector behavior. In detectors of the beam type, the light source and photocell are mounted near the ceiling on opposite

sides of the protected room. When smoke obscures the light below a predetermined value at the photocell, an alarm results. Detectors of the duct type are intended for detecting smoke in an air-handling system. A detector of this type is mounted directly on the outside of an air duct or nearby with a sampling tube extending about three quarters of the way across the inside of the duct. The air flows into the smoke detection chamber mounted on the outside of the duct, and back into the duct through a return tube, having a hole or holes directed downstream. As long as there is airflow in the duct, a portion of that air continuously flows through the detection chamber.

The diagram in Figure 12 shows a typical arrangement of functional parts. A pulsed light beam from a light-emitting diode (LED) with its associated optics is projected across the interior of a blackened chamber that may contain smoke to be detected. A photocell, with its optics, looks toward the projected beam along a line perpendicular to the beam. When smoke enters the chamber, the smoke particles reflect a small portion of the light beam toward the photocell, which provides a voltage to be amplified and causes an alarm. The light source may be monitored ahead of the smoke chamber and regulated to prevent variation of the light intensity from causing erratic detector behavior.

Figure 12 Typical arrangement of photoelectric smoke detector

components. In detectors of the beam type, the light source and photocell are mounted

near the ceiling on opposite sides of the protected room. When smoke obscures the light below a predetermined value at the photocell, an alarm results.

Detectors of the duct type are intended for detecting smoke in an air-handling system. A detector of this type is mounted directly on the outside of an air duct or nearby with a sampling tube extending about three quarters of the way

across the inside of the duct. The air flows into the smoke detection chamber mounted on the outside of the duct, and back into the duct through a return tube, having a hole or holes directed downstream. As long as there is airflow in the duct, a portion of that air continuously flows through the detection chamber.

IONIZATION SMOKE DETECTORS. A small amount of radioactive material ionizes the air inside a chamber that is open to the ambient air. A measured, small electrical current is allowed to flow through the ionized air. The small, solid particle products of combustion that enter the chamber as a result of fire interfere with the normal movement of ions (current), and when the current drops low enough, an alarm results. A two-position switch to control sensitivity may be provided. A detector of this type is shown in Figure 13.

Figure 13 Ionization Smoke detector

Modern ionization detectors have additional means to improve stability and immunity to atmospheric effects. A reference chamber is vented to the outside through a small orifice, which does not readily admit smoke particles. Temperature, humidity, and pressure changes are sensed by both the reference chamber and the smoke chamber, and their effects on alarm sensitivity are eliminated by electronic balancing. The major difference between detectors of the spot and duct types is the method of moving the smoke into the detection chamber. The spot type detects or relies on convection of air in a room. The duct type is intended. for detecting smoke in an air-handling system and is mounted directly on the outside of an air duct or nearby with sampling and return tubes extending completely across the duct.

TESTING SMOKE DETECTORS. Before testing detectors that are connected to auxiliary functions, such as release of a fire extinguishing agent, release of fire doors, or fan shutdown, disconnect or bypass the auxiliary functions (unless the test is specifically intended to test these features). Before

the test, notify the fire department and persons where the audible signals can be heard.

PHOTOELECTRIC detectors have a built-in test feature. In some models, a test light source actuated by a key-operated test switch or by a magnet held near a built-in reed switch causes light to reach the normally dark, smoke-sensing photocell in a quantity approximately the light of an average smoke test. In other detector models, the smoke simulation is performed by inserting a reflective surface into the smoke chamber so that the actual source light is reflected to the smoke sensing photocell. Test at least one detector in each initiating circuit (zone) monthly. Follow a rotation schedule so that all detectors are tested semiannually. Test failures or false alarms may result from an excessive accumulation of dust or dirt caused by an adverse environment. Blow out the smoke chambers with low-pressure air. (Partial disassembly of the detectors and disconnection of detectors' power, following the manufacturer's instructions, are required.) Since the photocell is normally dark, disassemble and clean it in a darkened area to minimize the photocell recovery time after cleaning before repowering the detectors. Allow approximately 30 minutes for recovery after reassembly of the detectors before reconnecting power. Disconnecting power by unplugging one detector may also disconnect power from the other detectors further from the power source. Inform the fire department before or during any extended testing period. Special equipment that may be required for cleaning consists of a low-pressure air source for blowing out dust and a suction cup for chamber cover removal. If the cleaning does not correct the false alarms or failure to alarm, return the detectors to the manufacturer for repair. Test at least one IONIZATION detector in each initiating circuit (zone) monthly. Follow a rotation schedule so that all ionization detectors are tested semiannually, following the manufacturer's instructions. Any detectors that produce false alarms between semiannual tests or do not test satisfactorily should be checked for sensitivity, following the manufacturer's instructions and using test equipment available from the manufacturer or other sources. An aerosol synthetic smoke is available from some manufacturers for testing their detectors. Unsatisfactory tests or erratic operation may indicate a need to remove accumulated dust or dirt. The frequency of cleaning should be based on results of regular tests and local conditions. Clean, check, and test operation and sensitivity, following the manufacturer's instructions. For loose dust deposits, blow the area with low pressure air after removing a protective cover. For more stubborn deposits, disassemble and clean, using a liquid recommended by the manufacturer. Recheck sensitivity and adjust if necessary after cleaning and drying thoroughly.

WARNING: Some smoke detectors of this type produce an electrical shock that may not be severe enough to cause injury directly but could cause a fall from a ladder. Some manufacturers, because of such possible injury to personnel or damage to the detectors, do not recommend servicing by anyone other than factory-trained personnel. Personnel in the customer service departments of most manufacturers can give advice on the telephone for specific problems. Be prepared to give the equipment model number and other pertinent information.

2.2.4 Flame-Actuated Detectors Flame-actuated detectors are optical devices that "look at" the protected

area. They generally react faster to a fire than nonoptical devices do. INFRARED FLAME DETECTORS. Figure 14 shows two typical infrared

(IR) flame detectors. IR flame detectors respond directly to the IR, modulated (flickering at 5 to 30 cycles per second) radiation from flames. The sensor design usually incorporates a delayed response, selectable in the range of 3 to 30 seconds, to minimize responses to nonfire sources of radiation. Thus, alarms are caused only by sustained, flickering source of IR radiation.

The IR flame detector is ineffective for smoldering or beginning fires. It is used where possible fires would develop quickly (fuels, such as combustible gases and liquids, or loose cotton fiber), and it is capable of protecting a large area if it is mounted high on a ceiling or wall. The sensitivity of IR detectors to a fire is affected by the distance of the device from the fire.

For example, if the distance is doubled, the fire has to be four times as large to be detected. To maintain immunity to possible nonfire sources of alarms, you should usually select longer response delays (10 to 30 seconds) for low ceiling mounting. Shorter delays, in the range of 3 to 10 seconds, are used when detectors are mounted on higher ceilings. For high-hazard areas, the detector can be mounted on a low ceiling and a low delay setting used to obtain sensitivity and fast response. Shields to eliminate possible false alarm sources

from the field of view of the detector are sometimes used, especially in a high-sensitivity application of the device.

Some detector models designed for fast response do not have the "flicker" discrimination feature, but instead have two sensors with different spectral responses. These sensors are used to distinguish between an actual fire and other sources of IR radiation.

Glowing ember detectors are nondiscriminating and fast acting. Ambient light levels must be maintained below 20 footcandles. Location and shielding are important for this type to avoid false alarms caused by incandescent lamps and sunlight.

ULTRAVIOLET FLAME DETECTORS. The ultraviolet (UV) flame detector is extremely fast and is used in high-hazard applications, such as aircraft maintenance areas, munitions production, and other areas where flammable or

Figure 14 Infrared flame detectors.

explosive liquids or solids are handled or stored. The detector responds to UV radiation not visible to humans. Figure 15 shows a typical UV detector. The detector and circuitry may be in a single housing or in separate housings. They act together as a normally open switch that becomes momentarily closed, causing an alarm, when UV radiation enters the detector viewing window. Response time is typically less than 25 milliseconds for an intense UV source. Some models have a built-in short time delay (3 seconds, nominal) to reduce responses to lightning and other momentary events. Frequently, separate relay contacts are provided for immediate and delayed alarm outputs, adjustable up to 30 seconds. A visual indicator, visible through the viewing window, usually indicates detector actuation. The UV detector is capable of use in explosive atmospheres, and some models have swivel mounts for directing them at specific hazards. Various models have angular fields of view ranging from 90 to 180 degrees. Sensitivity is usually factory set for the application.

TESTING FLAME-ACTUATED DETECTORS. Flame-actuated detectors should be inspected monthly for physical damage, accumulation of lens deposits, and paint. A spot of paint on a lens can prevent the detector from "seeing" a critical area in the protected space. Remove or protect the detectors when painting is being done. Be sure that auxiliary functions of the flame detection system are deactivated before testing is done unless these features are intentionally being tested. Before the test, inform the fire department and persons who would hear the alarm. False alarms or failure to detect during a test may be caused by environmental factors or the aiming of the detector. During the monthly inspection, check that detectors are not blocked and that lenses are shielded from direct rays of the sun and other sources of IR, such as welding equipment, in the case of UV detectors.

Figure 15 Ultraviolet flame detector If a detector has a clean lens but fails an operating test, make adjustments

and/or perform other field maintenance, following the manufacturer's instructions. Obtain field service by a factory-trained technician or return the equipment to the manufacturer for repair. Infrared Detectors On IR detectors (Fig. 14), the dark spot or dome at the bottom center of each IR device is the lens. Detector lenses must be kept clean to ensure the earliest possible detection of a fire. Test at least one detector in each initiating circuit (zone) monthly. Follow a rotation schedule so that all detectors are tested semiannually. A small soldering iron held 6 inches in front of a glowing ember detector can serve as a heat source for testing. A 250-watt IR heat lamp several feet from the detector can serve as a flame substitute in testing an IR flame detector. Ultraviolet Detectors. Keep UV detector lenses totally clean. A gradual buildup of contaminants frequently found in high-hazard spaces (oil, gasoline, petrochemicals, salt, and dust) block UV radiation. A layer thin enough to be undetectable to the human eye can cause a UV detector to be completely blind. Clean lenses according to the manufacturer's instructions. A test feature designed into some detectors allows for checking the optical integrity of the device. A small UV source inside the detector housing is shielded from directly illuminating the sensor. Local or remote operation of a test switch deactivates alarm circuits and illuminates the test lamp. The test lamp rays then pass through the front window to the sensor. Detector response to the test indicates that the window is clean and that the sensor and electronic circuits are operational.

2.2.5 Water-Flow-Actuated Detectors Sprinkler water-flow alarm-initiating devices are switches, just as fire alarm

initiating devices are. Normally open switches that close upon alarm are frequently used in end-of-line resistor circuits, though some normally closed

switches are used in normally closed loop circuits. However, the alarm-initiating devices for sprinkler water-flow mount differently and sense different conditions from fire-alarm-initiating devices. Sprinkler water-flow detectors are generally pressure actuated or vane actuated. Pressure switches are used on both wet- and dry-pipe sprinkler systems. Vane switches are widely used on wet-pipe sprinkler systems.

PRESSURE TYPE OF WATER-FLOW DETECTORS. Numerous styles of water-flow pressure switches of the pressure-increase type are found in wet- and dry-pipe systems (Fig. 16 shows one style).

The usual arrangement for switch actuation includes a sealed accordion like

Figure 16 Pressure-increase type of water-

flow detector

bellows that is assembled to a spring and linkage. The spring compression or tension controls the pressure setting of the switch and may be adjustable and/or factory set to the desired pressure. As water or air pressure in the bellows increases, it expands, providing motion against a spring. The linkage converts the motion of the bellows into the desired motion to actuate the electrical switch. If the pressure switch is used on a wet-pipe system, it is usually mounted at the top of a retarding chamber, which reduces the speed of pressure buildup at the switch.

There are also water-flow pressure-increase detectors that incorporate a pneumatic retarding mechanism within the detector housing. The retard time is adjustable to a maximum of 90 seconds with usual settings in the 20- to 70-second range. The retarded switch would be connected to the alarm port of a wet sprinkler system alarm check valve. The usual pressure settings for these switches are in the range of 8 to 15 psi. Pressure-drop detectors can be used in wet pipe sprinkler systems equipped with a check valve that holds excessive pressure on the system side of the check valve. These detectors are most frequently used where a water surge or hammer causes false alarms with other types of water-flow detectors. The construction of pressure-drop detectors is similar to that for pressure-increase detectors. The switch for a pressure-drop detector is arranged to actuate on a drop in pressure, and there is no retarding mechanism or chamber. A typical switch of this type would be adjusted for some normal operating pressure in the 50- to 130-psi range. The alarm pressure would be adjustable to 10 to 20 psi below the normal pressure.

VANE TYPE OF WATER-FLOW DETECTOR. A vane type of water-flow detector, used only in wet-pipe sprinkler systems, is shown in Figure 17. The vane (a flexible, almost flat, disk) is made of corrosion-resistant material. The detector is assembled to the pipe by drilling a hole in the wall of the sprinkler pipe. The vane is rolled up to form a tube and inserted into the pipe through the hole. Once inside the pipe, the vane springs open, almost covering the inside cross section of the pipe. The whole detector assembly is clamped to the pipe with one or two U-bolts. Gaskets and other sealing devices prevent leakage of

water out of the riser pipe and into the detector housing. Operation of a sprinkler causes water to flow in the system, moving the vane. A mechanical linkage connects the vane to an adjustable retarding device in the detector.

The retarding device, which is usually a pneumatic dashpot, actuates the alarm switch or switches and/or signal transmitter if the vane is still deflected at the end of the adjustable delay period. The retarding device prevents spurious alarms by delaying the mechanical actuation of the alarm switch(es) and/or transmitter to allow the vane and retarding mechanism to return to their normal positions after momentary water surges. The retarding-device setting is usually in the range of 30 to

Figure 17 Vane type of water-flow

detector

45 seconds, though the maximum setting may be as high as 90 seconds. TESTING WATER-FLOW-ACTUATED DETECTORS. Water-flow-

actuated detectors should be inspected monthly for physical damage and for paint on information plates and labels. Replace or repair damaged devices immediately. Clean or replace painted plates and labels. Correct other deficiencies promptly.

Test wet-pipe-sprinkler-system-water-flow devices by causing a flow of water equal to that from one sprinkler by opening the inspector's test valve fully. This valve is usually near the end of the sprinkler system on the opposite side of the building from the system riser. For sectional water-flow detectors, the inspector's test valve is usually on the opposite side of the section of the building from the riser. The inspector's test valve is left open to allow full flow until an alarm is indicated at the local control unit or, if the control unit is connected to the base alarm system, until a clear alarm is received at the alarm headquarters. One person with radio or telephone communications at the test valve and one person at each alarm-receiving location are usually needed for testing.

The delay between the start of full flow and receipt of the alarm signal should be between 15 to 90 seconds for retarded signals. Detectors that sense a pressure drop should respond in less than 15 seconds. If the alarm has not been received after water has been flowing for 3 minutes, stop the test and determine the cause of the problem. Dry-pipe sprinkler systems have an alarm test valve at the sprinkler riser in the trim piping that allows water from the supply side of the dry-pipe valve to exert supply pressure on a water-flow detector of the pressure-increase type. The alarm test valve is frequently a small lever valve but may be a globe valve. It should be permanently tagged Alarm Test Valve to expedite future testing.

The regular trip test of a dry-pipe sprinkler system to check the operating condition of the sprinkler system can also be used to test the water flow detector and alarm system if the tests are coordinated. However, it is not practical to trip-test the dry-pipe valve for every alarm system test. Do not open the inspector's valve at the end of a dry-pipe sprinkler system for an alarm system test unless a trip test is desired. The purpose of these initiating devices is to detect a fire condition and provide that information to the control unit. The control unit energizes the indicating circuit to warn building personnel for evacuation and to inform fire personnel of a fire.

2.3 ALARM-INDICATING DEVICES Alarm-indicating devices are the lights or sounding devices that indicate a

fire alarm or abnormal condition. These lights and sounds may also provide information about where the signal originates.

Indicating devices are divided into two major categories: visual (annunciators) and audible (bells, horns, chimes, and so forth).

2.3.1. Annunciators Annunciators give a visual indication of the "zone" or general area where

an alarm originated. In some cases, such as a sprinkler water-flow alarm, the annunciator can be arranged to identify the individual initiating device. In other cases, such as heat detectors, many initiating devices can activate the same indicator on the annunciator.

The annunciator indicator can be operated directly by auxiliary contacts in the initiating device or from a connection to the fire alarm control unit. A trouble or maintenance condition in the system wiring is also frequently annunciated by zone. Usually, a yellow or amber light indicates trouble and a red light indicates an alarm signal.

An annunciator may be incorporated into the fire alarm control unit, in which case it is generally actuated by connection to the control unit. It may also be located at a remote point, in which case it may be actuated either by the control unit or by auxiliary contacts in the initiating devices. Some installations may have a fire alarm control unit with an integral zone annunciator and a remote annunciator provided elsewhere. Frequently, the control unit standby battery is used to provide power for annunciator operation during power failure. Annunciator visual indicators may be of the drop type or the lamp type. Those of the drop type (which are essentially obsolete) use electromagnetic devices to move a flag into or away from a window to indicate a change in zone condition. Annunciators of the lamp type use pilot light assemblies to indicate an alarm or trouble condition (usually red for alarm, amber for trouble). The more common type of annunciator in use today is the lamp type. A frequently used incandescent lamp annunciator.

More recent annunciator designs use matrices or arrays of light-emitting diodes (LED’s). The advantages of LED’s are low current, long life, and small size, allowing annunciation of many zones in a small space.

2.3.2 Audible Signal Devices Any device that sounds an audible signal is classified as an audible signal

appliance. The audible signal appliances most frequently used in ship alarm systems are bells and horns. In addition, there are chimes, cowbells, buzzers, sirens, speakers, air horns, and steam whistles.

Figure 17 Audible signal appliances

Audible signals can be used to indicate either a fire alarm or a system-malfunction (trouble) condition.

The audible signal appliances are connected to audible signal circuits for alarm or trouble indication (depending on their function) at the control unit. Figure 18 shows some of the commonly used audible signal appliances.

Audible signal appliances have varying levels of sound output. Louder devices are for areas with high ambient sound levels or where the devices cannot be located near the area to be warned. Hospitals might use softer devices, such as chimes, to avoid frightening patients. Coded ships alarm systems normally use single-stroke versions of bells or chimes so the coded signal can be clearly produced. Vibratory bells, chimes, or horns are used for noncoded systems but can also be used in coded systems if the mechanism used can respond rapidly enough to provide an accurate rendition of the code being transmitted. If the fire alarm signal is coded, the coding provides the distinctive sound, and it is feasible (though not normal) to use the same bells for both functions. For a noncoded fire alarm system, necessary distinction of sound can be obtained by using a completely different type of audible signal appliance, such as a horn or siren, for sounding fire alarm signals.

2.3.3 Testing Alarm-Indicating Devices Test alarm-indicating devices monthly with the monthly inspection. When

convenient, the test may be combined with a fire drill. Test by operating the drill switch or the test switch at the control unit or by actuating an initiating device. If the test switch or an initiating device is used, notify the remote alarm headquarters because remote signal transmitters and other auxiliary features will be actuated by such a test.

While there is an alarm condition, check all the indicating devices and note any that fail to operate properly. Audible devices should produce loud, clear, consistent tones, and coded system codes should be clearly recognizable. Visual devices should be bright and steady or pulsating, as intended. Test annunciator lamps by operating a "lamp test" switch if it is provided; otherwise, cause an alarm and a trouble condition on each zone. It is usually convenient to cause these conditions at the control unit initiating circuit terminals. When a single indicating' device fails to operate, it is usually defective. If a group of devices fails to operate, the fault is usually a defective circuit.

2.3.4 Wiring and Equipment Schematic Diagrams. Complete, accurate wiring diagrams of each type of device in use, of each

circuit as installed, and equipment schematic diagrams. The descriptive information in manufacturers' data sheets on all equipment

in use and manufacturers' instructions for any special testing and maintenance. Figure 19 represents a typical ship fire alarm system.

Figure 19 Typical fire alarm system schematic diagram. 2.3.5 Indicating circuit faults An open- or short-circuit fault in an indicating circuit causes a trouble

indication at the control unit. A ground fault may also cause a trouble indication if ground-fault detection is a feature of the control unit.

a. Short Circuit. A short-circuit fault in an indicating circuit is difficult to detect by the usual test methods because the normal circuit resistance is quite low. A short circuit is just a low resistance in parallel with the low-resistance indicating devices. The symptoms would be a blown fuse at the control unit or power supply during a routine system test or fire drill and audible devices that do not operate as loudly as usual.

b. Open Circuit. In a two-wire parallel circuit, one open-circuit fault near the control unit would deactivate all the indicating devices. The only sign of an open circuit fault is the failure of one or more indicating devices during an alarm system test or fire drill.

c. Grounded Circuit. A single ground fault in an indicating circuit may not cause any symptoms unless the indicating circuit is AC-line powered. If the ground fault is on the "hot" side of the AC circuit and the indicating circuit is tested, a fuse or circuit breaker at the control unit or at the power panel supplying

the alarm system will blow. A ground fault on the neutral side of the indicating circuit causes no symptoms. Two ground faults on opposite sides of the indicating circuit are also a short circuit.

This system operates on the basic theory of a 20-volt DC circuit that has less than 2,000 ohms of resistance being supplied to the detector or detector processors. This voltage is provided from the control unit. A rise in ohmic value of the circuit to 100,000 ohms will trigger an alarm or tamper condition in the control unit. If you think about that for just a minute, isn't that the way our supervised fire alarm circuit operates? Sure it is! One main point to remember in any alarm system is that a small change in current flow (less than one-tenth of an ampere) can be used to activate an alarm. Our basic Ohm's law provides that a rise in resistance causes a drop in amperage in the same circuit. When the control cabinet receives an alarm or tamper signal, it then transmits the signal over telephone lines to the monitor cabinet.

2.4 PERIODIC SHIPBOARD DRILLS 2.4.1. Fire drills and on-board training 1. The Organization has been informed that in a number of recent

passenger ship fires, some of which have resulted in a high number of fatalities, the crew's performance during fire emergencies has been inadequate.

2. On-board personnel should receive periodic training and drills to become well versed in fire-fighting and fire safety measures. Resolution A.437(XI) "Training of crews in fire-fighting" contains information on land-based fire-fighting training for marine personnel. Land training is essential, but by itself insufficient.

The crew should know how to deal with fires on their ship because even the location of fire-fighting equipment on "sister" ships may vary from ship to ship. The common practice of transferring crew members from one ship to another at frequent intervals means that without on-board training and drills they may not become sufficiently familiar with the fire safety features of the ship on which they are serving.

3. Current regulations in chapter II-2 of the 1974 560;120sSOLAS Convention, as amended, do not require on-board training or drills for fire emergencies and although chapter III requires that fire drills be held at "monthly intervals in cargo ships, at weekly intervals in passenger ships, and lays down various other requirements regarding the conduct and recording of fire drills (see regulations 18, 25, 51 and 52), its detailed requirements for fire drills are not considered sufficient.

4. The Maritime Safety Committee, at its fifty-eighth session, agreed that the SOLAS Convention, as amended, should-be-.further amended to contain a new regulation covering on-board training and fire drills.

5. Further, the Maritime Safety Committee, recognizing the need to increase the state of awareness on board ships, instructed the Sub-Committee to prepare appropriate guidance for Governments and owners and operators in the conduct of on-board fire training and fire drills.

6. Annex I shows amendments to the Convention concerning fire drills and on-board training approved by the Committee, at its fifty-eighth session. Annex 2 provides guidance for incorporating these requirements into the crew's routine through minimum standards for on-board fire training and drills.

7. Member Governments are invited to give effect, as early as possible, to the draft new regulation to the 1974 SOLAS Convention, as amended, as contained in annex 1, pending the adoption of an amendment to the Convention, and additionally to encourage shipowners, ships' crews and port fire brigades to co-operate in practicing fire drills in port locations to ensure more efficient fire-fighting arrangements at such locations.

2.4.2 New regulation of the 1974 SOLAS convention. Fire drills and

on-board training Fire drills

1. Each member of the crew shall-participate in at least one fire drill every month. A drill shall take place within 24 h of the ship leaving port if more than 25% of the crew have not participated in a fire drill on board that particular ship during the previous month. The Administration may accept other arrangements that are at least equivalent for those classes of ships for which this is impracticable.

2. In passenger ships, a fire drill with the participation of the crew shall take place weekly.

3. Each fire drill shall include: a. reporting to stations and preparing for the duties described in the

fire muster list required by regulation III/8; b. starting of a fire pump, using at least the two required jets of water

to show that the system is in proper working order; c. checking fireman's outfit and other personal rescue equipment; d. checking the relevant communication equipment; e. checking the operation of watertight doors, fire doors and fire

dampers; f. checking the necessary arrangements for subsequent abandoning

of the ship. 4. Fire drills shall, as far as practicable, be conducted as if there were an

actual emergency. 5. Fire drills should be planned in such a way that due consideration is given

to regular practice in the various emergencies that may occur depending on the type of ships and the cargo.

On-board training and instructions On-board training and instruction in the use of the ship's fire-extinguishing

appliances shall be given at the same intervals as the drills. Individual instruction may cover different parts of the ship's fire-

extinguishing appliances, but all the ship's fire-extinguishing appliances shall be covered within a period of two months.

Each member of the crew shall be given the necessary instructions for their assigned duty.

Availability of fire-extinguishing appliances a. Fire-extinguishing appliances shall be kept in good order and be

available for immediate use at all times. b. The equipment used during drills shall immediately be brought back

to fully operational condition and any faults and defects discovered during the drills shall be remedied As soon as possible.

c. Records. The date and details of the fire drills shall be recorded as prescribed in regulation III/18.5.

2.4.3. Minimum standards for on-board fire training and drills Owners and operators are urged to take measures to improve crew

performance during shipboard emergencies. The human factor is very important. Each member of the crew should be instructed to recognize the importance of the emergency organization procedure and should take their role in this organization procedure seriously. Guidance should be given to each employee crew member to highlight the importance of this philosophy.

Fire drills An emergency organization procedure should be established to fight fires

and deal with abandon ship emergencies, which should include all members of the crew and there should be one organizational structure for both fire and abandon ship situations, since both may occur during the same incident. This procedure should include:

1. conduct of fire drills as if an actual emergency existed, all hands reporting to their respective stations prepared to perform the duties specified in the station bill;

2. starting the fire pumps using a sufficient number of outlets to show that the system is in proper working order;

3. bringing all rescue and safety equipment from the emergency equipment lockers and designated crew members demonstrating their ability to use the equipment;

4. operating all watertight doors and all fire doors; and 5. making an entry into the log for each drill, including the date and hour,

length of time of the drill, the number of lengths of hose used and a statement of the condition of all fire equipment, watertight door mechanisms and valves. If at any time the required fire drills are not held,

or only partial drills are held, an entry should be made stating the circumstances and extent of the drills held. On-board training On-board training should include:

1. instruction on: a. the purpose and meaning of the ship's station bill, fire control plans

and muster stations; b. each individual's assigned duties and the equipment issued; c. the meaning of the ship's many alarms;

2. on-board refresher training, including lectures, training books and equipment demonstrations, including warnings on ways to prevent fires (good housekeeping, smoking, etc.), fire hazards from common shipboard supplies (paints, cooking oil, lubricants, etc.) and first aid techniques (burns, broken bones, cardiopulmonary resuscitation);

3. learning to work within the emergency organization/procedure, including working with individual's superiors, his co-workers and his subordinates, as applicable, and for those in charge exercising leadership;

4. instruction on the purpose of the ship's passive fire protection design features and the purpose and requirements of the shipboard fire patrol;

5. location and operation of shut-downs for ventilation fans, fuel and lubricants; the manual fire alarm boxes and the ship's fire-fighting equipment; and the fire doors and ventilation dampers;

6. instruction and drills on extinguishing fires including: a. how a single crew member can extinguish small fires; b. special measures needed to combat fires involving dangerous

goods, electrical installations and liquid hydrocarbons; c. use of the ship's fire-fighting equipment (e.g. fire hoses, fire

nozzles, portable and semi-portable fire extinguishers and fire axes) including any post-drill clean-up and equipment stowage;

d. dangers from fire-fighting systems, e.g. carbon dioxide system discharges;

7. use of breathing apparatus, fireman's outfits and personal equipment, including lifeline and harness;

8. instruction on: a. means of escape from any-location in the ship, including all

stairways, ladders and emergency exits; b. procedures covering the search and evacuation of passengers from

all locations in the ship; c. the importance of closing doors after searching staterooms, not

leaving fire hoses in doorways and not using elevators; 9. location of first-aid equipment and of medical facilities; 10. how to transport injured individuals; 11. first-aid techniques, including treatment for burns, bleeding and broken

bones and cardiopulmonary resuscitation.

Availability of fire-extinguishing appliances The following equipment should be tested periodically:

1. detection systems, alarm systems, walkie-talkies, public address and other communications systems;

2. fixed fire-extinguishing connections (e.g. fire hydrants); 3. watertight doors and self-closing fire doors; 4. pressure of portable and semi-portable fire extinguishers and shut-downs

for ventilation, fuel and lubrication systems; 5. fire pumps, emergency fire pump, emergency Generator and the

pressurized water tank, as appropriate; 6. international shore connections; 7. fire main system, hoses and nozzles; 8. inventory and condition of the contents of repair lockers

However, only a portion of each type of fire-fighting and fire-detection equipment, e.g. some and not all of the fire hoses, need to be tested during each drill. A plan for periodically exercising each piece of equipment should be developed.

Records

1. The date and details of the fire drills should be recorded, as prescribed in SOLAS regulation III/18.5.

2. Records of crew members who participated in the training sessions and drills should be kept by date. An assessment of new crew members should be made prior to departure and the main office notified of their training status.

3. Records of the equipment tested at each drill should be kept by date. 2.5 LOCATION OF FIRE-FIGHTING APPLIANCES AND EMERGENCY

ESCAPE ROUTES 2.5.1 Ship construction arrangements The 1981 Amendments to the 1974 SOLAS Convention introduced major

changes in structural fire protection on new cargo ships of 500 tons and over. These Amendments formed the basis of the Merchant Shipping (Fire Protection) Regulations 1984, which came into force on I September 1984. New cargo ships are required to comply with one of three methods of structural fire protection: Method 1C, which requires all bulkheads, ceilings and linings to be non-combustible; Method I1C, which imposes no restriction on the materials used for bulkheads, ceilings and linings but requires a sprinkler system to be provided; or Method 1IIC, which permits combustible bulkheads, ceilings and linings within a network of 'A' and 'B' Class divisions with the provision of a fire-detection system. All three methods require corridor bulkheads to be 'B' Class divisions, the stairways to be enclosed and accommodation and service spaces and control

stations to be separated from other spaces by 'A' or' B' Class divisions. Tankers are required to comply with Method IC with additional requirements.

On 20 November 1981 the first set of Amendments to the 1974 International Convention for the Safety of Life at Sea (1981 SOLAS Amendments)1 were ratified by the Maritime Safety Committee (MSC) of the International Maritime Organisation (IMO). These Amendments came into force on 1 September 1984. The fire-protection requirements in these Amendments were incorporated in the Merchant Shipping (Fire Protection) Regulations 19842 (Regulations). This is the first occasion that fire protection, detection and extinction for all types of ships have been incoporated in a single Statutory Instrument. Previously the fire-protection requirements for passenger and cargo ships were embodied in the Construction Regulations for the respective ship types.

This paper is concerned only with the structural fire-protection requirements for new cargo ships and tankers of 500 tons and over, which are dealt with in Parts VII and VIII of the structural core does not rise more than 200 °C above the ambient temperature at any time during a standard fire test of 60 min duration for 'A' Class divisions and 30 min duration for *B' Class divisions. Aluminium alloy structures supporting the lifeboat and liferaft stowage, launching and embarkation areas arc to be insulated such that they meet the temperature limitation for "A" Class divisions.

The use of aluminium alloy in lieu of steel is prohibited by the cost of fitting the insulation required to comply with the core-temperature limitation.

Method of fire protection (Regulations 113 and 131(1)) One of the following methods of fire protection is required to be adopted in

the accommodation and service spaces of a cargo ship: • Method IC. All internal divisional bulkheads are to be 'B' or 'C Class

divisions without the necessity to fit an automatic sprinkler, fire-protection and fire-alarm system (sprinkler system) or a fixed fire-detection and fire-alarm system (detector system).

• Method IIC. A sprinkler system is required to be fitted in all spaces in which fire may originate with no restriction on the materials used in the construction of the internal divisional bulkheads, ic combustible materials such as chipboard may be used.

• Method IIIC. A detector system is required to be fitted in all spaces in which fire may originate with no restriction on the materials used in the construction of the internal divisional bulkheads except that the area of any accommodation space or spaces bounded by 'A' and/or 'B' Class divisions is not to exceed 50 m2. Permission may be given for this area to be exceeded in public spaces. As far as tankers arc concerned there is no alternative but to use Method IC. Irrespective of which method of protection is adopted all cargo ships and

tankers built on or after 1 September 1985 are required to be fitted with smoke detectors in corridors and over stairways within accommodation spaces.

Corridor bulkheads and other 'b' class bulkheads (regulations 114 and 131)

In all three methods of fire protection corridor bulkheads are required to be 'B' Class divisions. Every *B' Class bulkhead is to extend from deck to deck and to the shell or other boundaries unless continuous 'B' Class ceilings and/or linings arc fitted on both sides of the bulkhead, in which case the bulkhead may terminate at the continuous ceiling and/or lining. Figure 20 illustrates arrangements satisfying these requirements.

Fire integrity of bulkheads

and decks (Regulations 115 and 132)

Spaces throughout a ship are classified into categories according to their fire risk. The fire integrity of a bulkhead or deck separating adjacent spaces on cargo ships or tankers, respectively, may be obtained by cross-referencing the appropriate categories of the spaces in tables 7 and 8 or 9 and 10 in the Regulations. Where there is doubt as to the classification of a space it is to be treated as a space within the category having the most stringent boundary requirements.

Continuous 'B' Class ceilings or linings in association with a deck or bulkhead, respectively, may be accepted as contributing, wholly or in part, to the required insulation standards of an "A" Class division.

The insulation standards of 'A' Class divisions are to be maintained at the intersections and boundaries of such divisions. The importance of this requirement cannot be too highly emphasized. There is no sense in leaving these intersections and boundaries unprotected because the ability of a division to withstand fire is only as good as its weakest point. Figure 21 indicates where ribands of insulation are required at the intersections and boundaries of a typical machinery casing. Figure 22 indicates similar precautions to be taken when insulating a typical "A" Class deck.

Similar precautions must be taken when bulkheads and decks arc insulated with linings and ceilings, respectively.

Figure 20 Arrangements when `B` Class corridor bulkheades are fitted: (a) deck to deck and (b) and (c) stopped short of the

deckhead

Protection of stairways and lifts within accommodation and service

spaces (Regulations 116 and 133) Stairways are required to be constructed of steel except where the use of

equivalent material is approved. Every stairway and lift is to lie within an enclosure or trunk constructed of 'A' Class divisions of AO standard, except that an isolated stairway serving only two decks need only be enclosed at one level by 'A' Class divisions of AO standard or -B" Class divisions of BO standard. However, where a stairway abuts a machinery space of Category A. a ro-ro cargo space or a cargo pump room, the fire integrity of the bulkhead separating the stairway from the machinery, cargo space or pump room shall be determined by reference to table 7 or 9 in the Regulations as appropriate. Doors serving stairway enclosures or lift trunks are to be of the same' A' or 'B' Class standard as the bulkheads in which they are fitted.

Figure 23 shows three methods of enclosing stairways, all of which have been accepted by the MSC as complying with the Regulations in the 1981 SOLAS Amendments relating to the enclosing of stairways serving more than two decks.

The Department recently agreed to a request made by the General Council of British Shipping (GCBS) to apply no higher standards on UK registered ships than those imposed by the International Conventions and interpretations of the Conventions accepted by the MSC. Consequently any of the three arrangements

Figure 21 Three methods of insulating a typical

machinery casing, showing the ribands of insulation at

the boundaries and showing the ribands of insulation at

intersection

Figure 22 Two methods of insulating a typical `A` Class deck shoving the ribands of

insulation at the boundaries and intersections

shown in Fig. 23 is now accepted by the Department as complying with the Regulations, even though for the 10 years prior to this request the Department had only accepted the method shown in Fig. 23(a) on tankers in compliance with the Merchant Shipping Regulations in force during that period.

Although Fig. 23(a) and (b) comply with the strict interpretation of the 1981 SOLAS Amendments there are doubts about the arrangement shown in Fig. 23(c) because the stairways in this arrangement are not enclosed at each level as required by the Amendments. It is the author's opinion that the arrangements shown in Fig. 23(b) and (c) do not afford the same degree of protection as that provided by the arrangement shown in Fig. 23(a). which would impose no more restrictions on the accommodation layout than the other arrangements, as can be seen by comparing the plan views in Fig. 24. Moreover, it would afford a much safer means of escape and access for fire parties when corridors arc filled with smoke and toxic gases.

Openings in 'A' Class

divisions (Regulations 117 and 134)

The effectiveness of 'A' Class divisions in resisting fire is not to be impaired by penetrations such as pipes, cables, ducting, beams etc. Penetrations are treated as follows, and are also insulated to the same standards as the divisions for a

distance of 380 mm from the plating. Steel piping is simply welded to the bulkhead or deck to maintain integrity.

Plastic piping and metal piping with low melting points arc required to pass through 900 mm long close fitting steel sleeves of 3 mm minimum thickness welded to the bulkhead or deck. In the case of vertical plastic piping passing

Figure 23 Stairways more than two decks

Figure 24 Plan wiews of stairways shown in Figure 4(a) and (b)

through more than one tween deck the piping in alternate tween decks must be of steel.

Cables are required to pass through either any proprietary cable gland approved by the Department or 450 mm long steel spigots of 3 mm minimum thickness welded to the bulkhead or deck, with mineral wool insulation packed tightly in the spigot between and around the cables and sealed at each end with a flexible sealant.

Ventilation ducts penetrating 'A' Class divisions are treated as indicated below under 'Ventilation systems'.

Doors fitted in 'A' Class divisions are to be of designs approved by the Department. Doors fitted in 'A' Class bulkheads forming part of a stairway enclosure or lift trunk serving, accommodation and service spaces and control stations, and every door fitted in the boundary bulkheads and casings of a machinery space of Category A, are to be self-closing. Doors serving a machinery space of Category A are also to be reasonably gastight. Any hold-back arrangements fitted to these self-closing doors are to have remote releases which will automatically close the doors if the control system is disrupted and which will permit them to be closed manually. Watertight doors need not be insulated but this does not include weather-tight doors as is sometimes assumed.

It is imperative that bulkheads are properly stiffened when openings arc cut in them for 'A' Class doors and the openings properly faired. Doorframes are not designed to compensate for the removal of plating and stiffeners. Most problems associated with fire doors such as distortion of frames and/or door panels, binding of hinges, inability of latches to engage the frame properly etc. are invariably the result of inadequate compensatory stiffening in way of the bulkhead openings.

Openings in 'B' Class divisions (Regulations 118 and 135) The effectiveness of 'B' Class divisions in resisting fire is not to be

impaired by penetrations such as pipes, cables, ducting, beams etc. Steel piping is collared to the bulkhead or ceiling, the collar being fitted in two halves and screwed to the division. Plastic piping and metal piping with low melting points are required to pass through 900 mm steel sleeves collared to the division in a similar manner to steel piping.

Cables are to pass through 450 mm long steel conduits, the conduit being collared to the division in a similar manner to steel piping, with the ends of the conduit being sealed with a flexible sealant. When a steel conduit is unsuitable the cables are to pass through a 450 mm long steel spigot, the spigot being collared to the division in a similar manner to that used for steel piping, with mineral wool insulation packed tightly in the spigot between and around the cables and sealed with a flexible sealant.

Ventilation ducts penetrating 'B' Class divisions are treated as indicated below under 'Ventilation systems'.

Doors fitted in 'B' Class divisions are to be of designs approved by the Department. Doors fitted in 'B' Class bulkheads forming part of a stairway enclosure are to be self-closing. Hold-back arrangements fitted to these self-

closing doors are subject to the same conditions as those fitted to 'A' Class doors.

Ventilation openings in 'B' Class bulkheads are to be kept to a minimum and provided as far as practicable only in the lower part of a door and fitted with a steel grille or under the door, except that these openings are not permitted in a door in a 'B' Class bulkhead forming a stairway enclosure. The net area of the opening or openings is not to exceed 0.05 m2. The gap under a door fitted in a stairway enclosure bulkhead is not to exceed 6 mm, and 25 mm in the case of other 'B' Class doors. The grille is to be capable of being closed manually from each side of the door. Kick-out panels in 'B' Class doors are not required by the Department.

Ventilation systems (Regulations 119 and 136) Ventilation ducts which pass through 'A' and 'B' Class divisions are treated

as shown in Table I. The manual control of any damper in a ventilation duct must be directly

connected to the spindle of the damper, and therefore manual controls operable by push button, linkages or wires are not acceptable. There is no absolute guarantee with remote manual controls of these types that a damper will close when the control is activated. In order to satisfy the requirement for manual control on both sides of 'A' Class divisions, a damper is required to be fitted on each side.

However, in certain circumstances dampers need only be fitted on one side of the division, eg a duct passing through an 'A' Class stairway enclosure bulkhead need only have a damper fitted on the stairway side of the bulkhead. Fusible links when fitted must be on the inside of the ducts in order that they may be activated by the hot gases passing through the ducts.

Where a ventilation system penetrates decks, dampers are to be fitted in addition to those required to maintain the integrity of 'A' Class decks; this is to reduce the passage of smoke and hot gases from one tween deck to another through the system. Ducts serving stairway enclosures are to be taken from the fan room independently of other ducts in the system and are not to serve any other space.

When a control station is situated below deck means must be provided to ensure that the space is ventilated and kept free from smoke in the event of a fire in the ship. Unless the control station is situated on, or has access to, an open deck, or is provided with local closing arrangements equally effective in maintaining ventilation and freedom from smoke, there must be at least two entirely separate means of supplying air to the space. The air inlets must be situated such that the risk of both inlets drawing in smoke simultaneously is eliminated as far as is practicable.

Ventilation ducts, except those in cargo spaces, are to be constructed as follows:

1. Ducts having sectional areas of 0.075 m2 or more and all vertical ducts serving two or more tween decks must be constructed of steel or other equivalent material.

2. Subject to the requirements of 3 below, ducts having sectional areas of less than 0.075 m2, other than vertical ducts, must be constructed of non-combustible materials, except that the integrity of 'A' and 'B' Class divisions must be maintained as indicated below and in Table 1.

3. Ducts having sectional areas of 0.02 m2 or less and not more than 2 m long need not be constructed of non-combustible material subject to the following: (a) the ducts are constructed of material having regard to the risk of fire, (b) the ducts are used only at the terminal ends of the ventilation system and (c) the ducts are no closer than 0.6 m along their lengths to penetrations of'A' or 'B' Class divisions. Ducts provided for the ventilation of machinery spaces of Category A,

galleys, ro-ro cargo spaces or cargo spaces intended for the carriage of vehicles

Division Area of duct 'A' Class 'B'Class

0.02 m2 and under Steel ducts other than

spiroducts are to be collared and welded to division.

Steel ducts other than spiroducts are to be collared. Collars of steel or 'B' Class material.

Double spiroducts to be collared and welded to division or passed through 900 mm long steel sleeves welded to division.

Double spiroducts to be collared to division. Collars of steel or 'B' Class material.

Single spiroducts to be

passed through 900 mm long steel sleeves welded to division."

Single spiroducts to be passed through 900 mm long steel sleeves collared to division."

Over 0.02 m2 and not exceeding 0.075 m2

Approved damper units are to be fitted consisting of a 900 mm x 3 mm steel coaming incorporating a manually operated damper on each side of the division. In some instances one damper may be dispensed with. Ducts to be attached to ends of coaming.

Steel ducts other than spiroducts are to be collared to division. Collars of steel.

Double spiroducts to be collared to division. Collars of steel.

Single spiroducts to be passed through 900 mm steel sleeves collared to division. Collars of steel.

Over 0.075 m2

Approved damper units are to be fitted consisting of a 900 mm x 5 mm steel coaming incorporating an automatically/manually operated damper on one side and a manually operated damper on the other side. In some instances the manually operated damper may be dispensed with.

Steel ducts other than spiroducts are to be connected to 900 mm x 3 mm steel spigots collared to division or passed through 900 mm x 3 mm steel sleeves collared to division. Collars of steel.

Double and single spiroducts to be passed through 900 mm x 900 mm x 3 mm steel sleeves collared to division. Collars of steel.

Aluminium alloy ducting to be treated as single spiroducting. Where thickness of spigot is not specified it may be 1 mm or more "Steel sleeves fitted to prevent single spiroducts unwinding in fire.

Table 1: Treatment of ventilation ducts penetrating

'A' and 'B' Class divisions

having fuel in their tanks must not pass through accommodation and service spaces and control stations unless the ducts are either:

1. (a) Constructed of steel having a minimum thickness of 3 mm for duct widths or diameters of 300 mm or less and a minimum thickness of 5 mm for duct widths or diameters of 760 mm or more (the thicknesses of ducts having intermediate widths or diameters are to be determined by interpolation), (b) suitably supported and stiffened, (c) fitted close to each penetrated boundary with an automatic fire damper, which is also capable of being closed manually, and (d) insulated to A60 standard from each penetrated boundary to a point at least 5 metres beyond the fire damper; or

2. (a) Constructed of steel as in 1(a) and 1(b) above and (b) insulated to A60 standard throughout the accommodation and service spaces and control rooms.

Ducts provided for the ventilation of accommodation and service spaces and control stations must not pass through machinery spaces of Category A, galleys, ro-ro cargo spaces or cargo spaces intended for the carriage of vehicles having fuel in their tanks unless similar precautions are taken to those described above.

Exhaust ducts from galley ranges which pass through accommodation spaces or spaces containing combustibles must be constructed of 'A' Class scantlings and must be fitted with (a) a grease trap which is readily removable for cleaning, (b) an automatic fire damper located at the lower end of the duct, (c) arrangements which are operable within the galley for stopping the exhaust fan, and (d) a fixed means of extinguishing a fire within the duct using either carbon dioxide or a water spray system.

Construction of ceilings, linings etc. (Regulations 120 and 137) When Method IC is adopted ceilings, linings, draught stops and their

supports in accommodation and service spaces and control stations are to be non-combustible. However, when Methods IIC and IIIC are adopted only ceilings, linings, draught stops and their supports in corridors and stairway enclosures serving accommodation and service spaces and control stations arc required to be non-combustible.

Restriction of combustible material (Regulations 121 and 138) Exposed surfaces in corridors and stairway enclosures and surfaces in

concealed spaces within accommodation and service spaces and control stations are to have a Class I surface spread of flame rating when tested to BS 476: Part 7: 1971. Other exposed surfaces in accommodation and service spaces and control stations and those in machinery spaces arc to have a Class 1 or 2 rating. This docs not, however, apply to furniture, furnishings, machinery and similar items.

Primary deck coverings in accommodation and service spaces and control stations arc to be of materials which have been tested satisfactorily, inter alia, to an ignitahility standard specified by the Department.

Insulating materials (ie for fire, thermal and acoustic purposes) are to be non-combustible when tested to BS 476: Part 4: 1970, except for those used in cargo spaces and refrigerated compartments and those used to insulate valves in hot and cold service systems, providing their surfaces have a Class I surface spread of flame rating. The exposed surfaces of vapour barriers and adhesives used in association with insulating materials are also to have a Class 1 rating.

Non-combustible bulkheads, linings and ceilings in accommodation and service spaces may be faced with combustible materials not exceeding 2.0 mm in thickness, except for those in corridors, stairway enclosures and control stations where the combustible materials must not exceed 1.5 mm in thickness.

Miscellaneous items of fire protection (Regulations 122 and 139) In accommodation and service spaces and control stations pipes intended

to convey oil or other flammable liquids arc to be of suitable material having regard to the risk of fire, and overboard scuppers, sanitary discharges or other outlets close to or below the waterline are not to be of heat-sensitive

Figure 25 Two typical metal vapour barriers materials as the failure of such materials could give rise to. serious flooding.

Electric heaters are to be fixed in position and constructed so as to minimise the risk of fire. Their elements must not be so exposed as to scorch or

set on fire clothing, curtains etc. Waste-paper baskets are to be of non-combustible materials and have solid sides and bottoms.

Where insulations are exposed to oil and oil vapours they are to be faced with impervious materials.

Spaces behind ceilings or linings within accommodation and service spaces and control stations are to be divided by close-fitting draught stops spaced not more than 14 m apart and closed at each deck.

Special arrangements in machinery spaces (Regulations 124 and

141) The number of openings to machinery spaces is to be the minimum

compatible with the proper working of the ship. Any machinery space of Category A which is accessible from an adjacent shaft tunnel is, in addition to any watertight door, to be provided with a lightweight steel fire-screen door located on the shaft-tunnel side of the bulkhead and capable of being operated from each side.

Additional requirements for tankers (Regulations 129) The exterior boundaries of superstructures and deckhouses enclosing

accommodation and service spaces, control stations and cargo control stations, and any overhanging deck which supports such spaces, are to be insulated to A60 standard for the portions facing the cargo area and on their sides for a distance of 3 m from the boundary facing the cargo area. However, the insulation need not be fitted to the boundaries and overhanging decks of the wheelhouse and the external boundary of any space permitted to have a door fitted in this boundary, as indicated below. The following conditions apply to the exterior boundary facing the cargo area of superstructures and deckhouses enclosing accommodation and service spaces:

1. Doors must not be fitted except for those serving spaces which do not have access to accommodation and service spaces and whose internal boundaries are insulated to A60 standard.

2. Sidescuttles and windows other than wheelhouse windows must be of a non-opening type. Windows must not be fitted in the first tier of superstructures or deckhouses on the upper deck and sidescuttles in this tier are to be fitted internally with steel deadlights. Sidescuttles and windows fitted in higher tiers other than the wheelhouse windows are to have permanently fitted or portable steel shutters.

3. Air inlets and other openings are not permitted. Additionally the above provisions apply to the exterior side boundaries of

the superstructure and deckhouses enclosing accommodation and service spaces for a distance of at least 4% of the length of the ship but neither less than 3 m nor more than 5 m from the boundary facing the cargo area. This requirement does not apply to the exterior boundaries of the wheelhouse.

Windows and sidescuttles must not be fitted in internal or external boundary bulkheads and decks of machinery spaces of Category A and cargo pump rooms, or in skylights to such spaces, except that windows and

sidescuttles may be fitted in a bulkhead separating a machinery space of Category A and a control room located within its boundaries. Skylights to machinery spaces of Category A and cargo pump rooms are to be capable of being opened and closed from external positions.

2.5.2 Materials and fittings used in the construction of 'A' and 'B'

class divisions The Department approves materials and fittings for use in the construction

of 'A' and 'B' Class divisions on UK registered ships and the approvals are dependent on satisfactory fire tests being carried out on specimen constructions by testing laboratories acceptable to the Department. Drawings showing how materials and fittings are to be used are examined and modified as necessary and then endorsed with the stamp of the Department. Certificates referring to these drawings and indicating the conditions under which the materials or fittings are to be used are issued to the manufacturers, who are required to inform their customers of these conditions.

Figure 26 Methods of erecting `B` Class bulkheads: (a) and (b) fitted deck to deck, (c) stopped short of deckhead and (d) fitted deck to deck

incorporating a curtain plate

'A' Class insulations The types of insulation used for 'A' Class bulkheads are mineral wool,

sprayed and panel. Mineral-wool insulations, which for the purpose of this paper include ceramic-fibre insulations, are secured to the bulkhead by means of welded steel pins of 3 mm diameter spaced about 350 mm apart, wire netting and spring steel washers. Mild steel washers are unsuitable because they do not grip the pins. There are minor variations to this arrangement; eg instead of fitting spring steel washers the pins are bent over at right angles to hold the wire netting in place. The pins must not be bent in one direction only because the wire netting may slip from under them.

The density of mineral-wool insulations must be within ±10% of the nominal density stated by the manufacturer, which may be easily checked by weighing the slabs. For A60 standard, mineral-wool insulations are required to be fitted over the bulkhead plating in two layers of equal thickness, or as near equal thickness as possible, with the butts and seams in the two layers staggered.

When metal vapour barriers are used they must not be fitted directly over the insulation because in a fire the metal will expand and buckle between the pins and cut into the insulation, thereby reducing its effectiveness. There should be at least a 20 mm air gap between the insulation and the metal vapour barrier. Figure 6 shows two methods of fixing these barriers.

Sprayed insulation approved by the Department consist of either a cement/mineral-fibre base or a cement/vermiculite base mixed with water. Steel split pins are welded to the structure to form a key for the insulation. Half the thickness of insulation is then applied and the split pins bent over. Spraying is continued until the approved thickness has been applied. The insulation is applied by operators trained by the manufacturers. Some manufacturers use loosely fitted wire netting pinned to the structure instead of the split pins.

Panel insulations may be of the homogeneous-board type or the steel-sheet-faced mineral-wool type and are usually free standing, ie fitted independently of the bulkhead. Panels which are insufficiently robust to be free standing in service are bolted to the bulkheads. In order to stop these panels from becoming damaged as the bulkheads distort during a fire, the bolts are fitted with nylon nuts which melt and allow the panels to become free standing as the bulkheads bow away from them. Panel insulations are required to be fitted deck to deck and must be erected as shown on the approved drawings, ic at the correct distance from the bulkhead and using the correct jointing profiles.

'A` Class decks may be insulated on the underside by using mineral-wool or sprayed insulation in a similar manner to bulkheads, by ceilings constructed of homogeneous panels or insulated steel panels, or by overdeck insulations incorporated in deck coverings. No internal bulkhead or lining other than a steel bulkhead must penetrate the ceiling or deck covering.

' B' Class bulkheads and ceilings `B' Class bulkheads fitted deck to deck or from deck to continuous 'B'

Class ceiling are to be erected as shown in Fig. 26. The gap above the top edge

of the bulkheads allows them to move independently of the structure during a fire and also protects them from damage from vibrations or other movement of the structure.

Although the Regulations require 'B' Class bulkheads to be fitted from deck to deck or from deck to a continuous ceiling they must not penetrate 'A' Class overdeck insulations. They must also be attached to the non-combustible part of the deck covering, and any combustible material laid over 'A' Class overdeck insulations must not be laid under the 'B' Class division (see Fig. 27).

Smoke and toxicity Little has been done at IMO

about smoke and toxic gases even though these are the principal causes of fatalities in (ires. The main reason why little has been done is that the problem is complex and virtually insoluble. The situation has been partly alleviated by the use of flamc-rctardant materials to enclose organic foams used in furniture.

It has been suggested that a positive air pressure should he maintained in corridors and stairway enclosures by supply fans independent of the ships' normal ventilation systems in order to prevent the ingress of smoke and toxic gases. This appears to be a very good idea and worthy of investigation.

Conclusions Unfortunately the

improvements in structural fire protection on cargo ships discussed in this paper arc unlikely to he reflected in casualty records for some time because ships built prior to 1 September 1984 and those of less than 500 tons built after that date are not covered by the Regulations. Investiga tion is needed into the protection of crew and passengers from smoke and toxic gases, and if means could be found to reduce the amounts of these products in fires, the reduction in casual-tics could be quite dramatic.

Figure 27 Methods of attaching `B` Class bulkheads to two types of overdeck insulation: (a) bottom

chanel welded to expanded metal and (b) bottom chanel welded to expanded

metal to non-combustible board

COMPETENTA 3 FIGHT AND EXTINGUISH FIRES 3.1 SELECTION OF FIRE-FIGHTING APPLIANCES AND EQUIPMENT

3.1.1 Portable fire-fighting and dewatering equipment Aboard ship, sailors use portable fire extinguishers to extinguish fires in

compartments or in the galley. A fire-fighter’s ensemble provides protection for fire fighters, and the ensemble is enhanced by various types of breathing apparatus (BA) or emergency breathing apparatus (EBA) for use when fire fighting or conducting gas-free testing or inspection. Additionally, dewatering equipment, which includes pumps and eductors, may have to be used when fighting fires along with other portable equipment, such as fans and blowers. The characteristics and operation of these types of equipment are presented in this chapter.

3.1.2. Portable fire extinguishers Portable fire extinguishers are used aboard all ships, and the three types

most often used are as follows: • Dry chemical (powder) • Carbon dioxide (CO2) • Aqueous film-forming foam (AFFF)

1. Dry-chemical (powder) extinguishers Portable dry chemical extinguishers (fig. 1) are used primarily on class B

(BRAVO) fires. Purple-K-Powder (PKP) is the chemical most often used in these extinguishers. The dry chemical dispensed from the extinguisher interrupts the chemical reaction producing a fire and this action stops combustion.

PKP is most often used in these extinguishers. This dry chemical is also safe and effective for use on class C fires; however, carbon dioxide (discussed later in this chapter) is preferred, because PKP will foul electrical and electronic components. Also, PKP should not be used on internal fires of gas turbines or jet engines unless absolutely necessary, because of its tendency to foul engines.

The most common size of PKP extinguisher is the 10 kg size. These extinguishers also come in a 6 kg and a 12 kg size. Most of the PKP extinguishers have a small CO2 cartridge mounted on the outside of the extinguisher shell. This cartridge provides the propellant charge for the

extinguisher. Do NOT pressurize the PKP extinguisher until you are ready to use it.

The procedure for operating a

dry-chemical extinguisher is as follows:

1. Carry the extinguisher to the scene of the fire.

2. Pull the locking pin from the puncture lever marked PUSH.

3. Push the puncture lever down to cut the seal of the CO2 cartridge. The extinguisher is now ready to use.

4. Approach the fire from the windward side, if possible. Hold the extinguisher in one hand and the nozzle in the other hand.

5. Discharge the dry chemical by squeezing the squeeze grip on the nozzle. Hold the nozzle firmly and direct the dry chemical at the base of the fire. Use a wide sweeping motion from side to side. This will apply a dense, wide cloud

of dry chemical in the area. 6. Be certain that all of the fire in the area in which you are working is

extinguished before you move in farther. If the fire appears to be too large or if there is a possibility of being outflanked or surrounded by flames, attack the fire with the assistance of two or more personnel using extinguishers.

7. Do not try to economize on the dry chemical. Use as much as necessary (and as many extinguishers as necessary) to completely extinguish the fire.

8. Always back up dry chemical with water or foam. After a dry-chemical extinguisher has been used, invert the cylinder,

squeeze the discharge lever of the nozzle, and tap the nozzle on the deck. This will release any pressure left in the cylinder and cartridge and any dry chemical left in the hose and nozzle. By inverting the cylinder, you prevent further discharge of dry chemical and conserve the powder. Make sure that dry chemical does not remain in the hose and nozzle; it will cake up and clog them.

To recharge a dry-chemical extinguisher, proceed as follows: 1. Invert the extinguisher and tap the side of the cylinder with the nozzle to

knock down any loose dry chemical. Then bleed off the pressure.

Figure 1 Dry-chemical extinguisher

2. Remove the fill cap. Do NOT lean over the top of the extinguisher when removing the fill cap.

3. Fill the cylinder with dry chemical only to the bend in the tube. The extra space allows the powder to be aerated when the cylinder is pressurized. This ensures that the powder will not be caked when it is applied.

4. Remove any dry chemical from the internal threads of the bottle and from the threads of the cap.

5. Replace the fill cap. To install a new CO2 cartridge, proceed as follows:

1. Lift the lever cutter assembly and insert the locking pin. 2. If the extinguisher is to be restowed in the rack, pass a lead wire seal

through the locking pin and around the cutter lever. 3. Unscrew the expended CO2 cartridge. 4. Remove the cap and gasket from a new CO2 cartridge. 5. Screw the new cartridge, which has lefthand threads, into the female fitting

of the cutter assembly.

Figure 2. A portable 10 kg ABC dry powder fire extinguisher

2. Carbon dioxide fire extinguisher Aboard ship, carbon dioxide portable fire extinguishers equipment

includes 6 kg CO2 portable extinguishers, 9 kg CO2 and 45 kg CO2 wheeled extinguishers The carbon dioxide is contained under pressure in steel cylinders.

The standard ship CO2 fire extinguisher (Fig. 3 and 4) has a rated capacity (by weight) of 6kg of CO2. Removing the locking pin and squeezing the release valve built into cylinder valve operates it. CO2 extinguishers are primarily used on small electrical fires (class CHARLIE) and have limited effectiveness on class BRAVO fires.

Figure 3 6 kg carbon dioxide fire extinguisher.

Figure 4 A portable 6 kg BC carbon dioxide fire extinguisher

Figure 5 A portable 45 kg BC carbon dioxide fire extinguisher

The steps of the procedure you should adhere to for operating the CO2

extinguisher are as follows: 1. Carry the extinguisher in an upright position and get as close to the fire as

possible. 2. Place the extinguisher on the deck and remove the locking pin from the

valve. 3. Grasp the insulated handle of the horn. Rapidly expanding CO2 causes

the horn to become quite cold. 4. Squeeze the operating lever to open the valve and releaseCO2. Direct the

CO2 toward the base of the fire. This distance is reduced if the wind is against you and increased if the wind is with you. If possible, attack the fire from the windward side to increase the range and also to protect yourself from the fire. Move the horn slowly from side to side and advance on the flames as they recede.

5. When conditions permit, close the valve. Continue to open and close the valve as the situation requires. When continuous operation is necessary or when the valve is to remain open for recharging, slip the D-yoke ring on the carrying handle over the operating handle. The operating handle should be in the depressed position when you put on the D-yoke ring. The D-yoke ring permits continuous operation as long as any CO2 remains in the extinguisher.

Since CO2 is 50 percent heavier than air, it tends to settle and cover the fire. A CO2 blanket separates the air from the fire. The fire is thus smothered. If there is some wind or a draft, you should work so the carbon dioxide will be drawn or blown over the fire rather than away from it. Even though carbon dioxide reaches a very low temperature as it expands from the cylinder, it has only a very slight cooling effect on the fire. CO2 is used primarily for its smothering effect, not for its cooling effect.

Carbon dioxide is most effective when it is used in confined spaces. When you are using CO2, keep the compartment closed and secure the ventilation to prevent unnecessary dilution of the CO2. Except in an emergency, you should not open a CO2-flooded compartment for at least 15 minutes after it has been flooded. This delay is a precautionary measure to give the burned substances time to cool down so that they will not reignite when air is admitted to the compartment.

Do not attempt to use CO2 unless you know what you are doing. In high concentrations, CO2 will cause suffocation as rapidly as it will smother a fire, unless proper precautions are taken. You may enter a CO2-flooded compartment, if necessary. However, you must use an approved breathing apparatus or a hose (air-line) mask. Do NOT use a gas mask. It filters the air but does not provide the necessary oxygen.

3. AQUEOUS FILM-FORMING FOAM FIRE EXTINGUISHER Portable Aqueous Film-Forming Foam (AFFF) fire extinguishers are used

to provide a vapor seal over a small fuel spill, extinguish small class BRAVO fires (such as deep fat fryers), and for standing fire watch during hot work.

The portable AFFF fire extinguisher (Fig. 5-6) is a stainless steel cylinder containing premixed AFFF concentrate and water.

Some important facts you should remember about the operation and use of an AFFF extinguisher are as follows:

1. The AFFF extinguisher is designed for use on class BRAVO pool fires; however, it may also be used on class ALPHA fires. AFFF is NOT recommended for use on class CHARLIE fires (energized electrical components).

2. Before attacking a fire, ensure the pressure within the cylinder is within the proper range, and remove the locking pin. To operate, squeeze the operating lever above the carrying handle. The extinguisher is capable of continuous operation or multiple bursts.

3. AFFF extinguishes class ALPHA fires by cooling. It is superior to water because AFFF has added wetting and penetrating ability. For small class ALPHA fires, apply AFFF to the base (source) of the fire.

4. AFFF extinguishes a class BRAVO fire or protects an unignited fuel spill by floating on the flammable liquid and forming a vapor seal.

5. Deep fat fryer fires often require special procedures to extinguish them. Combinations of AFFF and PKP may be needed to put out these fires and prevent their spread throughout the space or into ventilation ducting. AFFF

should only be directed at the back wall of the fryer, allowing the stream to flow onto the surface of the burning oil. This technique does not disrupt the cooking oil and allows the fire to be put out and a layer of foam to be developed over the oil. WARNING Do not direct AFFF directly into hot cooking oil because doing so can

result in immediate boiling of the AFFF. This violent boiling may result in hot cooking oil splashing out of the fryer onto fire fighters.

Figure 6. Portable 9 litre AFFF (aqueous-film-forming foam) (AB)

fire extinguisher.

3.2. FIRE-FIGHTING TACTICS Recall the characteristics of different classes of fire, the stages of a fire,

and the basic tactics and strategies to attack and extinguish different classes of fires, and the fire-fighting equipment used. As a Damage Controlman, you will most likely encounter different types of fires aboard your ship. Although fires have certain things in common, each fire has its own unique features. Examples

of some unique features of each fire are the type of material burning, the ease with which the fire can be isolated, or the location of the compartment it is in. With these factors in mind, it is easy to see that there are many things to consider when deciding what tactics to employ to attack a fire. Therefore, fire parties and repair lockers are trained to respond to a variety of situations.

3.2.1 Fire-fighting strategies Recall the characteristics of different classes of fire, the stages of a fire,

and the basic tactics and strategies to attack and extinguish the different classes of fires. As you become more proficient in fire fighting, combat evolutions, and dealing with engineering casualties, you develop the ability to handle more than one single casualty at a time. Your training prepares you for cascading or multiple casualties, and the opportunity to practice your training should be a learning experience. A mass conflagration is a worst-case scenario. Your ability to think clearly in the face of multiple casualties may someday save your ship. The ability to shore up a weak bulkhead is not learned from a book – you must practice. Do you have the skills to rig casualty power cables to return a vital system to service? There are many such scenarios; keeping your cool and remembering your training is vital to the survival of your ship. Your training prepares you to take on different positions on an attack team, or in a fire party. Should a personnel casualty require a replacement, fire party qualifications allow personnel to replace each other as needed. Fire can spread in many different ways. Radiant heat from an intense fire may ignite materials in an adjacent compartment, or it may travel through inoperative ventilation ducts, which failed to shut.

Openings between compartments, including cableways, may contribute to the spread of fire. The first sign of the fire spreading is smoke. If you are an investigator, you must constantly rove an assigned area outside the primary fire boundaries. Report any encounters with smoke outside the primary fire and smoke boundaries; then use your breathing apparatus to investigate, if possible. If the fire spreads, then the secondary boundary becomes the primary boundary, and personnel must attack this new threat to the ship. It is the job of the damage control chain of command to make fire-fighting decisions that are based on reports from the scene, from investigators. A small fire can become a blazing inferno in a very short period of time, quickly making a compartment or area of the ship uninhabitable. When your ship is underway, you cannot use the strategies and methods used ashore. You cannot wait for the fire department.

3.2.2 Properties and dynamics of fire Recall the properties and dynamics that are characteristic of each of the

four classifications of fire. There are four classifications of fire and each classification has its own distinct properties and dynamics.

Class A (alpha) fire Generally speaking, a class ALPHA fire is any fire in which the burning

material leaves an ash. Paper, wood, and cloth are examples of this fuel, and are located throughout your ship. These solid fuels must be heated to their ignition point before they will burn, and there must be enough oxygen to support the fire. For a solid fuel to burn, it must be changed into a vapor state. This chemical action is known as pyrolysis and is defined as a chemical decomposition due to the application of heat. This decomposition creates a fuel vapor, which, mixed with oxygen, produces a fire. Removal of any one of the three elements of the fire triangle (heat, oxygen, and fuel) will extinguish a fire. A common method of attacking class ALPHA fires is the application of water. The water cools the fuel below its ignition point, thereby removing heat from the fire triangle and thus extinguishing the fire. On larger fires of this type, aqueous film-forming foam (AFFF) will be more effective than seawater. In all such fires, other nearby combustibles (including unseen materials on the other side of that bulkhead) must either be moved or kept cool to prevent further spread of the fire.

Class B (bravo) fire A class BRAVO fire presents challenges not encountered in other types of

fires. This is because they can be fueled by any of the flammable liquids stored aboard ship, including fuels, liquid lubricants, and solvents. Class BRAVO fires may be extinguished with Halon, AFFF, purple-K powder (PKP), or a combination of agents. The single most important step in combating this casualty is to secure the source of the fuel. One of the characteristics of a flammable liquid is known as flashpoint, which is the lowest temperature at which the liquid will give off sufficient vapor to form what is known as an ignitable mixture. When mixed with air at this minimum temperature, this vapor will ignite if an ignition source is present.

WARNING Fuels and other liquids stored aboard ship are often pressurized (to pump

them to other areas of the ship), or may be stored under pressure to minimize the release of vapors. Leaks in these pressurized fuel systems will tend to spray outward, and they often atomize, increasing the possibility of coming into contact with an ignition source. As an example, the ignition source could be a heated surface in an engineering compartment or an electrical spark from a faulty electrical component. When flammable liquids spill or leak from a pressurized source, they will cover a large area, release a great amount of vapor, and produce a great amount of heat when ignited. One of the specifications of flammable liquids is that they have a minimum flashpoint. Anytime a ship is refueled, the fuel it receives is tested for both quality and for flashpoint. Some flammables require special storage, often in special lockers with temperature detection and sprinkler systems installed. Some of the materials stored in these lockers are paints, welding gases, flammable cleaning solvents, and other materials. An accurate inventory of hazardous materials stored in such lockers should be readily available. Fuels for portable fire-fighting pumps and special

small boats may sometimes be stored on the weather decks of the ship. Your ship’s supply department can provide information about flammable materials (including safety and handling precautions, hazards, and minimum flashpoints).

Class C (charlie) fire A class CHARLIE fire is an energized electrical fire, and may be attacked

with nonconductive agents such as carbon dioxide (CO2) or with low-velocity water fog. Special care must be taken to maintain a safe distance from energized equipment. The most common (and safest) method of dealing with a class CHARLIE fire is to secure the electrical power, and treat it as a class ALPHA (burning insulation) fire.

WARNING Special care must be taken to avoid contact with energized electrical

equipment. CO2 bottles must be grounded, and the horn of the portable extinguisher must not come in contact with the energized equipment. If it is necessary to use water fog as an extinguishing agent, a minimum distance of 4 feet must be maintained. A straight stream of water must never be used on a class CHARLIE fire, due to the likelihood of electrical shock.

Class D (delta) fire Class DELTA fires are also known as combustible metal fires. This class

of fire results when materials such as magnesium, phosphorus, sodium, or titanium are ignited. Certain types of aircraft wheels are manufactured from these materials, as well as various pyrotechnic smokes and flares. Although some ships have pyrotechnic (referred to as “pyro”) magazines below decks, typically most occurrences of DELTA fires happen topside, where storage is more common.

Pyrotechnics often contain their own oxidants and therefore do not depend on atmospheric oxygen for combustion. For this reason, the exclusion of air, such as by use of PKP, foam, or other extinguishers, will typically be ineffective.

WARNING Class DELTA fires burn with an intense heat of up to 4500°F, and action

must be taken to shield your eyes from the brilliance of the flame. High velocity fog should be used to cover and cool these fires. If possible, remove the burning material by jettisoning it over the side of the ship. g it over the side of the ship. ng, you should apply large quantities of water at low pressure to cool the surrounding area. Class DELTA fires give off extreme amounts of heat and can produce explosions. Therefore, you must maintain a safe distance from the source of the fire while applying the water fog.

WARNING During a class DELTA fire, certain chemical reactions are occurring as the

water is applied to cool the surrounding area. This water reacts with the burning metal and forms hydrogen gas, which will either burn or explode, depending on

the intensity of the fire and the amount of burning material. In any case, maintain a safe distance from the fire and shelter yourself and your team from any potential explosions.

3.2.3 Dynamics of a fire The fact that there is a large variety of materials aboard any ship which

can burn and should be considered as fuels cannot be overemphasized. As stated before, for a solid fuel to burn, it must be changed into a vapor state. This chemical action is known as pyrolysis and is defined as a chemical decomposition due to the application of heat. This decomposition creates a fuel vapor. When this vapor is mixed with oxygen at the right temperature, a fire is produced. A solid fuel will burn at different rates depending upon its size and configuration. For example, a pile of wood chips or wadded paper will burn faster than an equal amount of solid wood or a case of paper. This fact is true because there is a larger surface area exposed to the heat; therefore vaporization occurs faster. Because more vapor is available for ignition, the fire burns more intensely and the fuel is consumed at a faster rate. A liquid fuel releases vapor much as a solid fuel does. However, it does so at a higher rate and over a larger temperature band. Because liquids have more loosely packed molecules, heat increases their rate of vapor release. These dynamics result in the fact that pound-for-pound liquid fuels produce about 2 1/2 times more heat than wood, and this heat is given off much more rapidly. If a flammable liquid is spilled (or is atomized and sprayed out under pressure) it covers a very large surface area and gives off much more vapor. This is one reason flammable liquid (class BRAVO) fires burn so violently. As mentioned earlier, the lowest temperature at which a liquid gives off sufficient vapor to form an ignitable mixture is known as the flashpoint for that liquid. An ignitable mixture is a mixture of vapor and air that is capable of being ignited by an ignition source. As an example, gasoline has a flashpoint of -45°F (-43°C). This factor makes gasoline a constant hazard because it produces flammable vapor at normal temperatures. Like gasoline, the other shipboard fuels have specified minimum flashpoints. To ignite, a flammable gas or vapor of a liquid has to mix with air in the proper proportion. The lowest percentage of gas that will make an ignitable mixture is called its lower explosive limit (LEL). If there is less vapor or gas than this percentage, then the mixture is too lean to burn. Conversely, there is also an upper explosive limit (UEL) above which the mixture is too rich to burn.

The range between the lower and upper explosive limits is called the explosive range of the gas (or vapor). Table 1 shows the flashpoint, LEL, UEL, and ignition temperature for a few of the flammable materials carried aboard ship. As an example, a mixture of 10% gasoline vapor and 90% air will not ignite, because the mixture is too rich (above the UEL). In this case a large amount of air must mix with a small amount of vapor to form an ignitable mixture.

Table 1. Properties of Selected Flammable Liquids and Gases

Fire Growth There are four distinct stages in the growth of a fire within a compartment

Figure 7 Stages of compartment fire growth

of a ship (fig. 7). These stages are known as growth, flashover, fully-developed fire, and decay.

During the growth stage of a fire (fig. 8), the average space temperature is low and the fire is localized near the area where it started. It is hot in the immediate vicinity of the fire, and rising heat and smoke create a hot upper level in the compartment.

Figure 8 Growth stage of a compartment fire In what is called the “rollover” of a compartment fire, a flame front of

burning gases is formed across the overhead of the space. Rollover takes place in the growth stage when unburned combustible gases from the fire mix with fresh air in the overhead and begin burning at some distance from the fire. Rollover differs from flashover in that only gases are burning in the space. The flashover stage is the period of transition from the growth stage to the fully-developed fire stage. It occurs in a short period of time and may be considered an event, much as ignition is an event in a fire. It normally occurs at the time the temperature of the upper smoke layer reaches 1100°F (600°C). The most obvious characteristic of flashover is the sudden spreading of flame to all remaining combustibles in the space. Personnel still in the compartment when flashover occurs are not likely to survive.

In the fully-developed fire stage all flammable materials in the compartment have reached their ignition temperature and are burning. The rate of combustion will normally be limited by the amount of oxygen available in the air to provide combustion. Flames may emerge from any opening; hatches, open ventilation ducting, etc. Unburned fuel vapor in the smoke may flash when it meets fresh air in adjacent compartments. There may be structural damage to bulkheads or decks when exposed to these extreme temperatures. A compartment may reach the fully-developed fire stage very quickly during

machinery space flammable-liquid fires or during enemy weapon-induced fires. As the available fuels and combustibles in the space are consumed the fire begins to decay. In the decay stage, combustion slows down (decays) and finally the fire goes out.

There are significant exposure thresholds for human tolerance to heat as shown in table 2, along with other temperature characteristics that may help you put them in perspective.

If a fire goes out quickly due to a lack of oxygen, such as in a tightly sealed compartment, fuel vapors may still be formed from any flammable liquid that is heated above its flashpoint. If fresh air is allowed into the space before this fuel vapor cools below its flashpoint, this mixture can ignite explosively. This is known as back draft, and fortunately, is an unusual occurrence.

Fire Spread If space personnel attack a fire early and efficiently, it can be confined to

the area in which it started. If the fire continues to burn unchecked, it can generate great amounts of heat that will travel away from the fire area, starting more fires wherever fuel and oxygen are available.

Table 2 Significant Exposure Thresholds

Steel bulkheads and decks and other fire barriers can delay but not prevent heat transfer. When a fully-developed fire exists in a compartment, the fire is most quickly spread to other compartments through openings such as doorways, vent ducts, and unsealed cableways. It will also spread to adjacent compartments by heat conduction through the bulkheads. Fires normally spread faster upward to the space above than to adjacent horizontal spaces simply because heat rises. Tests have been developed to provide typical temperatures, radiant heat flux, and length of time for material ignition by conduction through steel bulkheads from a fully-developed fire. In table 2 are provided to show you the characteristics of conduction.

Fire may spread through bulkhead penetrations such as electrical cableway openings. Although these openings are sealed, experience has shown that even armored cables will burn from extreme heat. Cableway fires may be hard to extinguish because they are difficult to cool because the grouping of multiple cables traps and contains heat. Also, cableways are often run through the overhead of compartments, and heavy smoke hinders finding the source of the fire. Older-style electrical cables will generate toxic black smoke from their insulation. Newer cables in use aboard ship are designed to reduce the amount of smoke generated.

3.2.4 Attack team considerations During the initial stages of a fire, the fire marshal proceeds directly to the

scene to direct efforts of the rapid response team. If a fire is beyond the capabilities of the rapid response team, the fire marshal shall turn his duties over to the scene leader of the at-sea fire party in order to coordinate this larger threat. These duties may include the following: 1. Overall command of the at-sea fire party. 2. Supervising the establishment and maintenance of communications. 3. Setting boundaries.

Providing necessary support to the at-sea fire party. The fire marshal assumes a “big picture” role, paying particular attention to the possibility of fire spread. He will also make recommendations for additional personnel

Type of attack Many factors go into the decision-making process to size up a fire, and

information is vital. The location, type, and size of the fire, available resources (including personnel), and fire growth all determine the overall plan of attack. Reports from the scene will include (1) location of fire, (2) class of fire, (3) action taken to isolate and combat the fire, (4) fire contained, (5) fire out, (6) reflash watch set, (7) fire overhauled, (8) compartment ventilated (9) compartment tested for oxygen, (10) compartment tested for flammable gases, and (11) compartment tested for toxic gases. Space personnel will evacuate when they are endangered, or the fire goes out of control. Every attempt must be made to account for all space personnel, since they may not all evacuate through the same exit. All evacuees will muster at a pre-arranged location outside of designated smoke and fire boundaries. Missing personnel must be reported to damage control central

(DCC). Use of bilge sprinkling and Halon activation (if installed) is documented, including time of activation. Other information may come from boundarymen or investigators. A boundaryman is responsible for observing a particular bulkhead or deck for signs of heat, such as smoldering or blistering paint, or smoke (particularly through bulkhead or deck penetrations). The boundaryman will attempt to cool the bulkhead to prevent spread of the fire as necessary. The investigators travel prearranged routes ensuring that fire and smoke boundaries are set, checking for Halon effectiveness, and making ongoing reports to their associated repair locker. When smoke is encountered, the investigators will immediately report it and don their OBAs prior to further investigation. Various circuits are available for the investigators to use to make reports, and many ships have hand-held radios for damage control use.

Affected/Damaged Systems The information necessary to effectively combat a large fire must include

an assessment of any damage to fire-fighting systems, as well as any major systems within the compartment that are not isolated and electrical isolation. The decision to secure compartment lighting rests with the on-scene leader.

Fire and Smoke Boundaries Fire and smoke boundaries are determined for each of the large

engineering spaces aboard your ship. The ship’s fire doctrine lists both primary and secondary boundaries. The boundaries are designed to effectively contain a fire to prevent its spread. Primary fire and smoke boundaries are set at all bulkheads immediately adjacent to the fire. Boundarymen will man these primary boundaries with a fire hose, and may have to cool the bulkhead to prevent spread of the fire. Fire could spread through any penetration, including ventilation, electrical cableways, piping conduits, or defective welds in cases of extreme heat. A secondary set of boundaries is set at the next immediate watertight bulkhead from the scene. If a boundary fails, and the fire cannot be contained at the first boundary, the boundaryman will attempt to secure the space and evacuate. What were previously secondary boundaries now become the primary boundaries. Boundary information is plotted by DCC and all repair lockers.

Reports (Halon, Bilge Sprinkling, etc.) Reports by evacuating personnel will include whether bilge sprinkling was

used, whether the source of the fire (such as leaking or spraying fuel) was secured, and whether Halon was activated. Investigators will attempt to determine whether Halon was effective by observing the color of smoke inside the space through the battle ports at the escape trunk. Smoke color may also be observed from topside, if the space is not completely air-tight, and reported to DCC. These reports help make the determination whether to immediately re-enter to combat the fire, or if it is already out, to allow the space to cool prior to entry.

Preparing to enter the space If you are a scene leader, your primary source of information is your locker

leader. The locker leader maintains plots of all damage control information throughout the ship, and will pass along all pertinent information to the scene leader. You are responsible for briefing your personnel and giving them the necessary information, so they will be better prepared to deal with conditions inside the compartment. Figure 9 shows an attack team preparing to enter a compartment.

Briefing Hose Teams Some of the information that hose teams must be briefed on are as

follows: (1) status of the fire to include location, type of fire (and is it still burning), was Halon effective; (2) status of the compartment: extent of major damage, equipment status, mechanical isolation, electrical isolation, boundaries); (3) watchstanders not accounted for; (4) activation of bilge sprinkling; and (5) planned method of attack. The ship’s main space fire doctrine provides a basic checklist for various personnel actions (including the damage control assistant, locker and scene leaders, and team leader), and is tailored to your ship. Other information may be important as well, depending upon your ship’s configuration or additional casualties to the ship or systems.

Figure 9 Attack team lighting off BA and preparing for compartment reentry.

Dressing Out You and other attack team personnel will assist each other as necessary

while donning personal protective equipment. You must ensure that your shipmate is properly dressed out. Personal protective equipment is intended to fit slightly loosely, especially gloves. This ensures that your skin has room to move somewhat inside this clothing. It also helps to keep hotter areas of the clothing from remaining in constant contact with your skin. This practice also reduces the likelihood of heat stress by allowing some air movement within the confines of the fire-fighter’s ensemble (FFE).

Checking Equipment When donning an EBA or SCBA, you should examine it and ensure it has

not been damaged while in storage. Your EBA canister should not show any sign of damage, which may prevent you from properly inserting or removing it. The copper foil seal must be in place. If the canister is not in good shape, replace it with a new one before entering the space.

NFTI. If the naval fire-fighter’s thermal imager. (NFTI) will be used, it must be warmed up in accordance with the manufacturer’s technical manual. Because it is very fragile, only qualified personnel will handle the NFTI. Most team leaders carry a spare battery for the NFTI. Helmet lights, handheld radios, voice amplifiers, and handheld fire finders are among the equipment that should be checked prior to re-entry.

Damage Controlmen maintain and test this equipment in accordance with PMS or with the manufacturer’s instruction. The NFTI is a device that allows the user to see through dense smoke and light steam by sensing the difference in infrared radiation given off by objects with a temperature difference of at least 4 degrees Fahrenheit. A small television-type monitor is built into the back of the NFTI, and displays these variations in temperature as a black and white image. Hotter objects will appear lighter on the screen than cooler objects. The NFTI has multiple uses, including locating the seat of a fire, locating injured personnel, and searching for hangfires and hotspots. The NFTI is battery-operated and displays five light emitting diodes (LEDs) when fully charged. A good practice is to change the battery when more than one light goes out during use. To conserve battery power, turn the NFTI off when not in use, and allow 1 minute for warmup prior to use. The NTFI has two modes of operation; pan and chop. The pan mode provides the greater sensitivity; however, the NFTI must be kept in motion or the image will fade out. The chop mode is best for fire fighting, allowing the user to focus on one area while holding the NFTI still. A blue button on the front of the NFTI allows you to change modes. Prior to compartment entry, you must ensure the NFTI is in the chop mode. When using the NFTI, it has been proven that slow, steady advancement, along with periodic scanning of the scene during an approach, helps the operator judge distances better. A side-to-side scan also provides important information on hazards in the area and the best direction in which to proceed. An occasional vertical scan will detect hazards above deck level, i.e. cableway or overhead fires.

Fire-fighters ensemble (FFE). The fire-fighter’s ensemble (FFE) consists

of fire-fighter’s coveralls, fire-fighter’s hood, damage control/fire-fighter’s helmet, fire-fighter’s gloves, and fireman’s boots, all designed to protect the fire fighter from the heat generated by a growing (pre-flashover) fire. For a flashover or fully-developed fire, the FFE provides only a few seconds of protection for escape. The fire-fighter’s glove size should be selected for a loose hand and finger fit to reduce heat transfer from continuous material contact and allow glove adjustment at hot points. Additional hand protection can be gained by wearing a flash glove as an extra inner liner to an over-sized fire-fighter’s glove. While waiting to enter the fire area, the FFE coveralls should only be donned to the waist, tying the coverall arms around the waist.

Accessing the Space Proper fire boundaries must be set prior to accessing the affected

compartment, to provide a safe area from which fire fighters can attack the fire. Electrical isolation must be complete prior to re-entry; the only exception is lighting. The on-scene leader will decide whether to secure compartment lighting. Complete electrical isolation helps to decrease the number of ignition sources inside the compartment. Mechanical isolation does not have to be complete prior to re-entry; however, it does provide greater safety for firefighters. Prior to space re-entry, there may be evidence that Halon and bilge sprinkling was not effective. If secondary Halon is available it should be used, and 7-11observed for effectiveness. Activate AFFF bilge sprinkling for 2 minutes prior to entry. If Halon was effective, allow at least 15 minutes prior to space entry. If Halon was not effective, re-entry should be attempted as soon as evacuation and mechanical isolation are completed.

Direct Attack The type of attack is determined from all information received. A direct

attack upon a fire involves entering the compartment, proceeding to the seat of the fire, and attacking it “directly.” ther direct attacks involve a fog attack into the overhead gases, or a direct attack upon the base of the fire from the compartment entrance. The accessman opens the hatch or door so that fire fighters can enter the compartment. If a fire has burned for a considerable time, the access hatch to the compartment may be jammed. It may be necessary to use forcible entry equipment, including bolt cutters, sledge hammers, pry bars, PHARS, and PECU.

Indirect Attack An indirect attack is used when conditions do not allow fire fighters to

enter the space. A fog spray is introduced from a cracked doorway or any available penetration. Upon completion, fire fighters will then enter the compartment and attack the fire directly. Compartment venting is another means of cooling the space so fire fighters may enter safely. An opening leading directly to an open weather deck area (or a large open compartment leading directly

outside) allows the hot gases overhead to vent. It may be desirable to cut a hole in the overhead leading outside. This hole should be at least 1 square foot in diameter to allow proper venting. Prior to entry, bilge prinkling (if installed) will be activated for 2 minutes.

Loss of Personnel Your training prepares you to take on different positions on an attack

team, or in the fire party. A personnel casualty requires you to find a replacement for that person. Battle damage may prevent a member of the fire party from reaching his or her GQ station. The key element is training, enabling personnel to perform a variety of functions in the fire party.

3.2.5 Fire attack and hose handling Hose team movements The first obstacle for a hose team member is often a ladder leading

downward. For safety, only one person should be on the ladder at a time. As the nozzleman advances, the hose team members pass the hose down to him while he descends the ladder. After he reaches the deck, the first hoseman will descend the ladder, followed by another hoseman, as needed to handle the

hose. As the hose progresses further into the space, more hose is needed, as well as hosemen.

The attack team leader usually operates the NFTI, looking for hotspots and hangfires. Although the team leader already knows the location of the seat of the fire, he must be alert to the likelihood that other parts of the compartment are on fire. The leader must also look for obstructions that prevent advancing to the seat of the fire. The team leader will also issue orders for hose advancement, and instructs the nozzleman to attack the fire with the necessary spray pattern. Hosemen follow the direction of the team leader, moving forward on the hose, advancing or backing up with the hose, and handling the weight of the hose. Whenever the nozzle is opened, a recoil effect pushes the hose backwards, and hosemen will push forward to compensate for this.

Heat Stress Extreme compartment heat, weight of the FFE, carrying heavy equipment,

and handling a fire hose are contributing factors to heat stress. As fire fighters rotate out of the compartment, the team leader and scene leader will coordinate relief personnel. Under harsh conditions, personnel working hard (such as the nozzleman) will need to leave the compartment sooner than others. A complete relief team should be standing by, ready to enter as needed, to relieve personnel in the space. Heat stress training is conducted as part of “all hands” training, and you must be aware of its symptoms and required treatment. The symptoms of heat stress are as follows:

• The skin appears ashy gray; the skin is moist and clammy • The pupils of the eyes may be dilated (enlarged)

• Vital signs are normal; but the victim may have a weak pulse and rapid shallow breathing

• Heavy sweating You may observe these symptoms in one of your shipmates after leaving the compartment. The treatment for heat stress is as follows:

• Loosen clothing; apply cool wet cloths • Move the victim to a cool or air-conditioned space, and fan the victim • Do not allow the victim to become chilled • If the victim is conscious, provide a solution of 1 teaspoon of salt dissolved

in a quart of water. • If vomiting occurs, do not give any more fluids Transport the victim to

sickbay (if manned) or the nearest battle dressing station for treatment by corpsmen Heat Stroke The symptoms of heat stroke are as follows:

• High body temperature • No sweating—skin is hot and dry • Pupils of the eyes may become constricted • Strong rapid pulse • Possible unconsciousness

During heatstroke, the body is no longer able to sweat, preventing removal of excess heat. If the internal temperature of the body rises above 105°, the brain, kidneys, and liver may all suffer permanent damage. In its earlier stages, the victim may have shown symptoms of heat exhaustion, as detailed above. The treatment of heat stroke may include:

• Immediately informing medical personnel,moving the victim to the coolest possible area, and removing clothing.

• Reduce body temperature immediately by dousing the body with cold water or by applying cold, wet towels to the body.

• Ensure the victim has an open airway. • Place victim on his or her back, head and shoulders slightly raised. • If cold packs are available, place them under the arms, around the neck,

at the ankles, and on the groin. This helps lower internal body temperature.

• Give the victim cools water to drink. Do not give any hot drinks or stimulants. Attacking a fire There are different methods for attacking a fire; however, no single tactic

or strategy is applicable to every situation. For example, in a multiple hose attack, it is possible to drive smoke and flames away from one hose team onto another team. Therefore, all attacks must be coordinated.

One of the dangers of opening an access to a compartment is that fresh oxygen is introduced into the space. If space temperatures are above the auto-

ignition point of any combustible materials, they may start burning again once fresh air reaches them. This is the reason for allowing a cool down period, assuming that Halon was used and was effective.

Direct Attack The ideal method of attacking a fire is a direct attack. This technique

involves short bursts with a narrow fog or direct stream, as directed by the team leader. Fire fighters advance into the immediate fire area and apply AFFF directly onto the fire.

Locating the Seat of a Fire All members of the fire party have been briefed regarding the location of

the fire from information received from space evacuees. Finding the seat of the fire probably will not be too difficult; reaching it may be another matter. In extreme temperature conditions, deck plates may warp, or ladders may fail. Move throughout the compartment with extreme caution.

Extinguishment Once the team leader and nozzleman have successfully reached the seat

of the fire, the team leader directs the nozzleman in foam application to extinguish any remaining fire. Different spray patterns from the hose nozzle are used as needed, either to break up any combustible material, or to cover a certain area with AFFF.

Prevention of Reflash AFFF is particularly effective against class BRAVO fires, because it serves

three distinct functions. As foam it floats on top of flammable liquids, preventing vapors from being released to the atmosphere. This foam also prevents oxygen from reaching the flammable liquid. The AFFF foam, being a mixture of concentrate and water, also provides a cooling effect. Therefore, covering hot spots with AFFF is highly effective in preventing reflash. Allowing the compartment to cool down prior to reentry (with Halon effective) also helps to prevent reflash.

Reflash Watch Once satisfied that the original fire is extinguished, the team leader

stations a reflash watch. The person assigned as reflash watch remains near the seat of the fire with a charged hose, and observes the area to ensure that no new fire breaks out. Normally at least one other hoseman remains on scene with the nozzleman to tend the hose in case a reflash occurs.

Hangfires and Overhaul Once the reflash watch is set, the team leader and a second hose team

search for hangfires. All areas of the compartment are examined with the NFTI, ensuring that no areas are missed. All cableways, areas beneath deckplates, and

overheads are examined to ensure no hangfires are missed. At various times, the team leader will make reports detailing percentage of overhaul. If

hangfires are found, they are extinguished. It is sometimes necessary to use overhaul equipment to pull smoldering or burning material (such as lagging) from an overhead or bulkhead in order to extinguish it.

3.3 ESMOKING AND ATMOSPHERIC TESTING 3.3.1 Desmoking Active desmoking is the process of removing smoke and heat from the

buffer zone prior to extinguishing a fire. This action aids fire-fighting efforts, and helps prevent the spread of smoke throughout the ship. Desmoking may be accomplished using ventilation fans in adjacent compartments or with portable fans. There will be some smoke in surrounding areas; smoke boundaries will help slow the spread of smoke. This type of desmoking should not be confused with the desmoking process of the affected compartment after the fire has been overhauled.

When a class BRAVO fire has been extinguished, combustible gases may be present. Operating electric controllers to start ventilation fans may ignite these gases. Desmoking with installed ventilation can proceed with minimal risk once specific conditions are met. These conditions include the following:

• The fire is extinguished and overhauled. • The AFFF bilge sprinkling has been operated. • The source of the fuel for the fire is secured. • The space has been allowed to cool. • All fuel has been washed to the bilges. • No damage has been sustained to the electrical distribution system.

Desmoking should begin once the compartment has cooled sufficiently so there is no danger from reignition. Circuit breakers that have tripped should not be reset until qualified personnel can make a damage assessment. Examine the electrical distribution system, and if possible, reestablish power to the installed ventilation fans. If the fans are fully operational, run them on high speed for a minimum of 15 minutes to remove smoke and toxic gases. If the installed system is partially operational or inoperative, desmoking will take longer, but can be accomplished by using portable blowers, or by providing a positive ventilation from adjacent spaces. On ships without Halon or AFFF bilge sprinkling, the safest method of desmoking is to exhaust the compartment with portable fans, or to provide a positive ventilation pressure from adjacent compartments.

Atmospheric testing Atmospheric tests are always conducted after desmoking is complete,

because combustible gas indicators will not operate reliably in a Halon atmosphere, and an oxygen analyzer is unreliable when its sensor is exposed to

excess moisture or comes in contact with particulates found in a post-fire atmosphere. When the space is clear of smoke, test the atmosphere for oxygen, combustible gases, and toxic gases. The level of oxygen must be between 19.5 and 22 percent. Combustible gases must be less than 10 percent of the lower explosive limit, and all toxic gases must be below their threshold limits before the space is certified safe for personnel without breathing devices. After a class BRAVO fire, the compartment should be tested for the following gases:

• Hydrocarbons • Carbon dioxide • Carbon monoxide • Hydrogen chloride • Hydrogen cyanide

If Halon 1301 was discharged into the compartment, a test for hydrogen fluoride must also be conducted. Shipboard personnel authorized to conduct these tests aboard ship are the gas free engineer and gas free petty officers. Required tests shall be conducted near the center and at all four corners, on each level of the compartment. At least one satisfactory reading at each location must be obtained.

Dewatering Dewater the compartment with the commanding officer’s permission, and

in accordance with operating procedures. Dewatering a class BRAVO pool fire will not commence until the space is completely overhauled, except in extreme conditions where ship stability is threatened. Dewatering will affect the vapor barrier on top of pooled flammable liquid, an extreme caution must be exercised to ensure the AFFF blanket is maintained until completion of overhaul. Following overhaul, normal dewatering may be conducted or completed at the same time as desmoking or post-fire gas free testing.

Compartment remanning Once the space is certified safe, remanning can begin. A careful damage

assessment is conducted, and once individual equipment or systems are verified operational and safe, then may be placed in service.

Investigation After overhaul, the fire should be investigated to determine the point of

origin, types of combustibles involved, path of fire spread, ignition source, and significant events in the growth and eventual extinguishment of the fire. Starting from the point of farthest fire spread, burn patterns will usually extend back to the area of origin. Efforts should be directed toward recreating the conditions that caused the fire, and identifying any changes in design or procedures that could have prevented the fire or lessened its spread and intensity. These changes are very helpful to ship designers and operators. Photographs, material samples, metallurgical samples, and failed equipment assist in reconstructing a fire history.

3.4. FIRE EXTINGUISHMENT In general, fires may be extinguished by removing one side of the fire

triangle (fuel, heat, or oxygen) or by slowing down the rate of combustion. The method or methods used in any specific instance will depend upon the classification of the fire and the circumstances surrounding the fire.

3.4.1 The removal of fuel Although it is not usually possible to actually remove the fuel to extinguish

a fire, there may be circumstances in which it is possible. If part of the fuel that is near or actually on fire can safely be jettisoned over the side, do so as soon as possible. Damage control parties must stand ready at all times to shift combustibles to safe areas. Take whatever measures possible to keep additional fuel away from the fire. In particular, immediately close supply valves in fuel oil, lube oil, and JP-5 lines.

Figure 10 Removal of fuel 3.4.2 The removal of heat The fire will go out if you can remove enough heat by cooling the fuel to a

temperature below that at which it will support combustion. Heat may be transferred in three ways: by radiation, by conduction, and by

convection. In the process known as radiation, heat is radiated in all directions. Radiated heat is what causes you to feel hot when you stand near an open fire. In conduction, heat is transferred through a substance or from one substance to another by direct contact from molecule to molecule. Therefore, a thick steel

bulkhead with a fire on one side can conduct heat from the fire and transfer the heat to the adjoining compartments. In convection, the air and gases rising from a fire are heated. These gases can then transfer the heat to other combustible materials that are within reach. Heat transferred by convection is a particular danger in ventilation systems. These systems may carry the heated gases from the fire to another location several compartments away. If there are combustibles with a low flash point within a compartment served by the same ventilation system, a new fire may start.

To eliminate the heat side of the fire triangle, cool the fire by applying something that will absorb the heat. Although several agents serve this purpose, water is the most commonly used cooling agent. Water may be applied in the form of a solid stream, as a fog, or used together with Aqueous Film-Forming Foam (AFFF)

Figure 11 Removal of heat

3.4.3 The control of oxygen Oxygen is the third component of the fire triangle. Oxygen is difficult to

control because you obviously cannot remove the oxygen from the atmosphere that normally surrounds a fire. However, oxygen can be diluted or displaced by other substances that are noncombustible.

If a fire occurs in a closed space, it can be extinguished by diluting the air with carbon dioxide (C02) gas. This dilution must proceed to a certain point before the flames are extinguished. To reach this point, all ventilation systems to the space must be secured. Once this point has been reached, no fire can exist.

In general, a large enough volume of C02 must be used to reduce the oxygen content to 15 percent or less.

AFFF foam will also keep oxygen from reaching the burning materials thus smothering the fire.

Figure 12 Control of oxygen 3.4.4 The reduction of the rate of combustion Dry chemical fire extinguishing agents and Halon 1301 do not extinguish

fires by cooling or smothering. Instead, they are believed to interrupt the chemical reaction of the fuel and oxygen. This reduces the rate of combustion, and the fire is extinguished quickly.

3.4.5 The importance of speed in fire fighting Speed is very important in fire fighting. If you allow a fire to burn without

confining or extinguishing it, the fire can spread rapidly. A small fire in a trash can may spread to other combustibles and become a large fire that could affect several compartments or even the whole ship. The cost of damage that may have originally been a few dollars could end up costing millions of dollars. Therefore, the ship's fire party must get to the scene with their equipment and start fighting the fire as soon as possible. Any delay that allows the fire to spread will make it more difficult to extinguish the fire with the personnel and equipment available.

4.3.6. Extinguishing agents The agents commonly used by ships’ fire fighters include water, AFFF, dry

chemicals, carbon dioxide (CO2), and Halon 1301. The agent or agents that you

will use in any particular case will depend upon the classification of the fire and the general circumstances.

Water Cooling is the most common method of fire extinguishment, and water is

the most effective cooling agent. Fortunately, water is available in large quantities. Of all the extinguishing agents being used by the ships, water has the greatest capacity for heat absorption. Therefore, you can cool most burning substances below their ignition points by the application of water.

Aboard ship you will normally apply water to the fire by the use of an all-purpose nozzle. We will discuss the all-purpose nozzle in more detail in other chapter of this training manual. The allpurpose nozzle allows you to apply water to the fire as a solid stream, as high velocity water fog, or as low velocity water fog. When you need to reach a fire that is some distance away, or when you need penetrating power, you should use the solid stream. However, water fog is preferred over a solid stream in most cases. A given amount of water in the fog will absorb more heat than the same amount of water in a solid stream. The total amount of water that must be pumped into the ship to fight a given fire will also be reduced when using the fog. All water used for fire fighting must be pumped overboard or otherwise disposed of; this is a definite advantage of using the fog form. In addition to cooling the fire, fog tends to smother the fire by displacing the oxygen.

Because of the cooling capacity of the finely divided water particles, fog can be used successfully on class B fires as well as on class A fires. If you use fog on a class B fire, you need to remember that a danger of a reflash exists until you cool the entire surface of the fuel down below the flash point.

Water is not recommended as an extinguishing agent for electrical fires except as a last resort. When water is properly broken up into a fine spray or fog by the nozzles operating at the designed pressure, the fog does not conduct electric current. But if you shift to a solid stream, or if you accidentally touch the nozzle or the applicator to the electrical equipment, the danger of electrical shock is great. Sometimes it may be necessary to use water fog to fight an electrical fire. In these cases, do not advance the nozzle any nearer to the power source than is absolutely necessary for proper use of the fog pattern.

Water fog gives you considerable protection by forming a screen of water droplets between you and the fire. This fog screen protects you against the intense heat of the fire. This gives you a certain amount of maneuverability in attacking the fire. Water fog also tends to dilute or absorb various vapors and to wash fumes and smoke from the atmosphere. You can help clear smoke from the area by occasionally directing the fog pattern upward for a few seconds.

Before you enter a burning compartment, reduce the heat and flame by a liberal application of water fog. Place the fog into the compartment through doors and other accesses. In the early stages of a large fire, a good deal of the fog applied will turn into steam. The steam will help to smother the fire. You must remember to stand clear of openings, since there is likely to be a violent outward rush of hot gases that are displaced by the steam.

Foam Foam is a highly effective extinguishing agent for smothering large fires,

particularly those in oil, gasoline, and jet fuels. Aqueous Film-Forming Foam (AFFF), also known as "light water," is a

synthetic, film-forming foam designed for use in shipboard fire fighting systems. The foam proportioning/injection equipment generates a white foam blanket. AFFF proportioning equipment will be discussed in chapter 5 of this training manual. AFFF is equivalent to seawater when it is used to extinguish class A fires.

The unique action of AFFF stems from its ability to make a light-water film float on flammable fuels. As foam is applied over the flammable liquid surface, an aqueous solution drains from the foam bubbles and floats out over the surface to provide a vapor seal. This aqueous film-forming action enhances extinguishment and prevents reflash, even when the foam blanket is disturbed. Fuels which have not been ignited may also be protected with this same action.

AFFF can be used alone or in combination with Purple-K-Powder (PKP), which will be discussed in the next section.

Dry chemicals Dry chemical powders extinguish a fire by a rather complicated chemical

mechanism. They do not smother the fire and they do not cool it. Instead, they interrupt the chemical reaction, known as fire, by suspending fine particles in the fire. In effect, the dry chemicals put a temporary screen between the heat, oxygen, and fuel and maintain this screen just long enough for the fire to be extinguished.

Several types of dry chemicals have been used as fire extinguishing agents. For ships use, the most important agent of this kind at present is potassium bicarbonate, also known as Purple-K-Powder or PKP. PKP is used to extinguish class B and class C fires because it is very effective against these fires. However, it is both corrosive and abrasive and should be used on class C fires only in emergencies. PKP is primarily used in portable 10kg extinguishers. However, 6- and 12kg portable extinguishers are also available for portable use. PKP can be used in conjunction with AFFF. Portable PKP extinguishers and the special equipment for using PKP and AFFF together are described in other chapter of this training manual.

Carbon dioxide Carbon dioxide (CO2) is an effective agent for extinguishing fires by

smothering them. That is, CO2 reduces the amount of oxygen available for combustion. This smothering action is temporary. You must remember that the fire can quickly rekindle if oxygen is again admitted to hot embers.

CO2 is a dry, noncorrosive gas that is inert when in contact with most substances. It is heavier than air and remains close to the surface. CO2 does not damage machinery or other equipment. Since it is a nonconductor of electricity, CO2 can safely be used to fight fires that might present electric shock hazards.

However, the frost that collects on the horn of a CO2 extinguisher does conduct electricity. Therefore, you should be careful and never allow the horn to come into contact with electrical components.

Aboard ship, CO2 fire extinguishing equipment includes 6 kg CO2 extinguishers, 45 kg CO2 hose and reel installations, and CO2 installed flooding systems.

Although CO2 is nonpoisonous, it is dangerous because it does not provide a suitable atmosphere for breathing. Asphyxiation can result from breathing CO2. BA or OBA's must be worn when CO2 is used below decks or in confined spaces.

Halon 1301 Halon 1301 (bromtrifluoromethane) is a relatively new fire extinguishing

agent used in the Navy. Halon 1301 is a colorless, odorless gas with a density approximately five times that of air. It does not conduct electricity or leave a residue. Halon 1301 is stored in compressed gas cylinders for shipboard use.

This extinguishing agent is effective against class A, class B and class C fires. The fires are not extinguished by smothering or cooling. The chemical reaction of fire is interrupted, as is the case of using PKP. Halon 1301 decomposes upon contact with flames that are approximately 900°F (482°C). For Halon 1301 to function effectively as an extinguishing agent, it must decompose. However, as it decomposes, several other products such as hydrogen fluoride (HF) and hydrogen bromide (HBr) are formed. Both gases are irritating to the eyes, skin, and upper respiratory tract. Chemical burns are also possible.

You should not stay in a space where Halon 1301 has been released unless you are wearing an BA or EBA. However, you can safely be exposed to concentrations of 5 to 7 percent for a period up to 10 minutes. In fact, carbon monoxide along with oxygen depletion, heat, and smoke present a greater danger to you than Halon 1301.

3.5 USE OF BREATHING APPARATUS FOR FIGHTING FIRE 3.5.1 Breathing apparatus and protective clothing The ‘normal’ environment you work in may have no detectable respiratory

hazards present. During a fire, chemical release or the sudden presence of dust particulates, things can change quickly and your respiratory system is extremely vulnerable.

Death related to respiratory harm can occur within four minutes. Initial collapse and unconsciousness may occur in seconds after exposure to various toxins and asphyxiating atmospheres. Once you’re down, you may never regain consciousness and may shortly die. How can you avoid this sod of tragedy?

TAKING PRECAUTIONS: There are day-to-day environments where the respiratory atmosphere is less than desirable. Personnel working in nuclear containment areas may be operating in atmospheres with sub-atmospheric

pressures and oxygen levels below normal. Laboratory employees may be working routinely in environments with toxins and other irritant products present in the ambient air. How are these employees protected? What steps can be taken to ensure survivability in both the routine and emergency response environments?

The most critical step in preparing for the proper selection and use of respiratory protection involves Air Monitoring. This process involves sampling the atmosphere that workers will be operating in and ascertaining what, if any, respiratory hazards are present.

The main concerns in air quality for respiratory use are (1) oxygen levels; (2) toxic products; (3) thermal effects; and (4) dust particles which may occlude the alveoli in the lungs. The following criteria establishes when one of these concerns becomes hazardous:

Oxygen - normal range is between 19.5% and 23.5% oxygen in ambient air Enrichment or deficiency can cause death;

Toxic Products - have Threshold Limit Values established for each chemical. The known TLV must be matched against ambient readings, then the

protection factor of the various respirators must be matched against the concentration level to ensure safe breathing air inside the mask for the user.

Thermal-flammable environments can pose significant danger to both the respiratory tract and the employee in general. Monitoring activity should detect and alarm occupants to evacuate at 10% of the Lower Flammable Limit of flammable products in the work environment.

Proper air monitoring techniques will assess what hazards are present and then a decision can be made on which respirator to choose for proper protection. Keep in mind that there are several choices for respirator protection, and they do not all provide the

same level of protection, nor the necessary level of protection in some cases. While the fire service strives for overprotection by wearing Self Contained

Breathing Apparatus (SCBA) on calls, even SCBA with positive pressure regulators may not provide acceptable protection against certain contaminants which can permeate directly through the facepiece!

While I realize that few firefighters monitor the air before entering contaminated environments, it would be a good idea if you at least knew what contaminants were present and what their concentration levels were.

The types of respirator protection units commonly used in industry are as follows:

AIR PURIFYING RESPIRATORS (APR5) - a respirator which operates by using filter cartridges or canisters which contain chemicals to neutralize or filter the effects of the airborne contaminants in the environment. (In my opinion, only

Figure 13 Facepiece (facemask)

full facepiece units can be recommended due to the fact that the eyes can easily absorb toxins);

SUPPLIED AIR RESPIRATORS (SAR’s) - a respirator which consists of a mask (again, a full facepiece is recommended) which is supplied by an air hose connected to a breathing air quality/grade supply source. The supply source is either a compressor or a cascade system of stored air in compressed air cylinders.

Devon Fire & Rescue Service is to reequip its fire fighters with ultra-lightweight carbon composite BA cylinders from EFIC Ltd. Devon’s fire fighters will be amongst the first in the world to use the new lighter cylinders which give weight savings of over 60% compared with traditional steel equivalents.

a. b. Figure 15.a, b, c. EFIC’s carbon composite cylinders. c.

Figure 14 APR: Draeger’s APR has filters which comply with COSHH

regulations and European standards. Circle No.102.

In January 1994, the UK’S Health & Safety Executive became the first national authority to approve the use of carbon composite cylinders. EFIC will supply Devon Fire & Rescue Service with nine-liter 300-bar cylinders which give a nominal duration of 60 minutes and weigh just 5.2kg. The EFIC cylinders will be used with interspiro’s Spiromatic 90 self-contained breathing apparatus. This order from Devon follows an announcement by another UK service, Wiltshire Fire Brigade, that it is to re-equip its firefighters with FFIC carbon composite cylinders. Both brigades hope to stand using the carbon composite cylinders in April1994.

If an employee is operating in an environment which has the potential of being Immediately Dangerous to Life and Health (IDLH), an escape bottle of emergency air supply must be worn and connected to the mask (I recommend at least 10 minutes of escape air, as long as you are within ten minutes of your escape area).

It’s a grim fact of life that the respiratory tract and lungs can be easily damaged by a variety of conditions found at fire/rescue scenes. As to the seriousness of a respiratory injury, well, let’s face it. If you can’t breathe you have a pretty severe problem on your hands.

Every ship firefighters should know that the respiratory tract can be damaged in milliseconds. Superheated air, toxic gases, oxygen-deficient environments, petroleum product vapors, etiological agents (bacteria, viruses etc.) and radioactive particulate matter (alpha particles) can all cause injury and/ or death to an unprotected human. Hence the development of self-contained breathing apparatus (SGBA) for respiratory protection.

Most of the early SCBA was designed for ship uses, such as mining. The need for breathing apparatus (BA) was especially critical for escape purposes and many of the BA sets were designed with nothing more in mind than this.

REQUIREMENTS and CHANGES Today’s breathing apparatus has many functions. Entry personnel require

BA for firefighting, rescue, Haz Mat incidents, cleaning and testing chemical tanks, working in oxygen-deficient environments and so forth.

With these many needs in mind, the technology and design of BA has changed - for the better I might add. Unfortunately, many of these changes have come about as a result of deaths and injuries where BA sets were misused or failed.

Probably the biggest improvement in recent years is the application of positive-pressure SCBA. This technology provides for a positive-pressure environment inside the facepiece, the wearer having a slight positive-pressure just above atmospheric pressure (slightly more than 1/27th of one psi).This eliminates the opportunity for toxic materials to be inhaled through leaks in the facepiece seal or through the facepiece itself.

Regulators have been relocated to the facepiece rather than worn on the side or waist belt. This allows the wearer to easily visualize the control valves on the regulator. My experience has shown that with the facepiece-mounted regulator units, there is less damage to the regulators, requiring less maintenance and certainly minimizing emergency incident potentials.

If the regulator is attached to the front seems to have less of a desire to smash the regulators against walls and fixed objects while performing emergency operations.

In addition, the advent of facepiece-mounted regulators has eliminated the low-pressure hose which formerly ran from the low-pressure side of the regulator up to the inhalation valve on the face-piece.

This flexible hose, dangling below your facepiece, can get caught on a variety of items in the course of duty. The low-pressure hose also has the potential to become damaged and leak. With positive pressure units, the toxics, at least, are not allowed entry into the wearer’s respiratory tract. However, the constant flow of air through a leak will reduce duration.

Manufacturers have released several versions of a quick-fill or buddy-fill system in recent years designed to quickly fill a BA bottle while it is still being worn. Some have suggested that this could be utilized to fill the BA of a trapped or injured firefighter who may be low on air.

There are various types and designs of BA on the market. Usually the equipment is divided by the design of open or closed-circuit. An open-circuit allows the wearer to breathe compressed air from a storage tank and then the exhaled air is expelled from the unit via an exhalation valve.

A closed-circuit design typically allows the wearer to breathe a mixture of oxygen mixed with exhaled air. As the wearer breathes, exhaled air circulates into a scrubbing element where the exhaled air is refined, mixed with oxygen and then reintroduced to the inhalation side of the BA.

The system is considered closed due to the exhaled air not being dumped immediately into the ambient environment, eventually by-products are released from the unit into the air The advantages to these systems include duration and the weight-relationship for the duration provided.

Earlier closed-system units had a tendency to warm up the air during the rebreathing phase. Cooling rings and other options are available to assist in maintaining a quality temperature range for the air supply.

While think that the concept of long-duration BA is great, one must keep in mind whether you have long-duration firefighters or not.

If your personnel are not physically fit or they are working in a high-heat environment where heat-stress is imminent, a 4 hour BA duration is something of a moot point, as the medics carry their own oxygen supply for patients.

Some ship applications, such as tank inspections, cleaning processes and deep-tunnel work lend themselves to long-duration equipment. Rescues in deep tunnel projects may require lengthy time periods simply to access the incident site; while BA must be worn, the rescuer is not being exerted-another case for long-duration BA.

Today’s harnesses are better designed for the comfort of the wearer Placement of the back-pack weight in a better anatomical position will increase wearer endurance, providing - that is - your personnel wear the pack the way it is supposed to be worn.

Of particular importance is the use of flame-resistant materials for today’s harnesses. Some unit seven have steel-strand materials with flame-resistant

fabric over the metals. The purpose of this concept is to prevent the harness straps from melting on the BA assembly during flashovers and high heat conditions.

While no-one plans to get caught in a flashover, it has happened. Today’s protective clothing can provide significant protection for the firefighter’s body. It is much easier to. escape from an environment with your breathing apparatus still attached to your body, rather than it dragging on the ground, pulling your facepiece off.

In-line BA systems are commonly used in industry and are finding a role in some rescue teams. An in-line system is based on a stored supply of compressed breathing air supplying a regulator and facepiece worn by the ship firefighter/ rescue worker.

The wearer does not have a full-size tank on his/her back and cannot extend the working distance past the length of the hose attaching he or she to the fixed air supply.

Most of these units have an escape bottle mounted on a waist bottle. However, this supply of air is minimal and is quality air.

While there have been improvements in the ability to communicate while wearing BA, I believe that we still have some way to go. With the advent of helmet/facepiece systems, we may start to see some quality communications. Integral systems that connect the BA facepiece to the helmet (or to a helmet that has the facepiece as part of its structure) are now being marketed by several manufacturers.

For some time the use of BA with fully encapsulated suits has provided responding personnel with interesting challenges. For example. Is it better to rip the suit off without the proper decontamination procedures being carried out when the air runs out - or become a properly decontaminated corpse?

That choice must no longer haunt us. There are connect-through units available which don’t destroy the integrity of the fully-encapsulated suit and allow supplemental air to be provided for the wearer.

Should ship personnel be equipped with the same level of protection as fire brigade/department personnel? The issue-like the question about wearing fully encapsulated suits depends on what you expect them to encounter and respond to.

Facing the same hazards as government firefighters, ship firefighters must be equipped in the same way indeed, they face the same injuries; fire does not discriminate. In some cases the ship firefighter may be expected to respond to more exotic conditions, requiring an even higher level technology, we must still consider the following important points:

• If you don’t have it on-site in the first place, all the technology in the world won’t help in an emergency. Plan ahead. Specify and purchase according to your needs;

• Without quality training and standard operating policies, technology may be used incorrectly. An untrained firefighter with sophisticated equipment may over-commit his/her position.

Our advances in technology still do not make us into Supermen. Your practices must support the application and use of your equipment.

3.5.2 Emergency (oxygen) breathing apparatus The type A-4 emergency (oxygen) breathing apparatus (EBA or OBA) is

used throughout the ships. The EBA is an entirely self-contained breathing apparatus. It enables the wearer to breathe independently of the outside atmosphere. It produces its own oxygen and allows the wearer to enter compartments, voids or tanks that contain smoke, dust, or fire, or those that have a low oxygen content.

Major EBA Components You will be required to wear, operate, and maintain in perfect operating

condition the type A-4 EBA. To do so, you must know the various components of the EBA and their purposes. Figure 15 shows the components and identifies them. As you read about the various components, refer to this figure as well as to those pertaining to the individual components.

FACEPIECE.- The facepiece (Fig. 15-1) contains the eyepiece, the speaking diaphragm, and the head straps. The eyepiece is a one-piece clear lens. A spectacle kit is provided that may be installed in the facepiece. Corrective lenses may be installed in the kit for individuals who require glasses. However, once the lenses are installed, only the person that the lenses are made for can

HARNESS AND WAIST STRAPS.- The EBA has two types of straps: harness and waist (Fig. 16). The harness straps go over your shoulders and snap into D rings. They support the weight of the EBA. The waist strap goes around your body and helps keep the EBA from swinging away from you.

EBA QUICK-STARTING CANISTER.- The quick-starting canister (Fig. 17) is painted Figure 15 Components of the EBA.

green. This is the canister that you will use for all evolutions other than training. The training canister is discussed later. Figure 15 shows a cutaway view of the canister. The rubber gasket provides an airtight seal when the canister is in the operating position in the EBA. The copper foil seal protects the chemicals from moisture until the canister is ready for use. The chlorate candle, which is built into the canister, produces oxygen for about 5 minutes. You will be able to breathe in the oxygen and exhale it just as if you were not wearing an EBA.

The moisture and carbon dioxide from your exhaled breath activate the chemicals in the canister. The chemicals in the canister cleanse your exhaled breath of the moisture and carbon dioxide and return the remainer of the air to you as you inhale.

The amount of your exertion will deter-mine how long the canister produces oxygen. The more active you are

The amount of your exertion will determine how long the canister produces oxygen. The more active you are, the faster the chemicals will be expended. The canister will last longer when you are doing mild work such as investigating shipboard damage. When you are involved in hard work, such as fighting a fire, the canister will last for about 30 minutes.

Your normal breathing habits will also affect the length of time the canister

will last. When you replace an expended canister with a new canister, do so only in fresh air.

Airflow System At this point, you should know and understand the use of each component

of the EBA. Figure 17 shows an EBA with a canister installed. The arrows indicate the airflow through the EBA.

As you exhale, moist breath passes through the exhalation tube (7), through the valve housing to the bottom of the canister (6), and upward through

Figure 16 Harness and waist strap

Figure 17 Cross-sectional view of quick starting canister.

the chemical. The carbon dioxide is absorbed, and the moisture present reacts with the chemical to give off oxygen. This oxygen passes into a breathing bag (4) (part of the breastplate group) from which the inhalation tube (3) allows the breathable mixture to be drawn into the facepiece (1) by your normal intake of breath.

Check valves (2 and 8) are used in the inhalation and exhalation passages. An automatically operated pressure-relief valve (5) in the breathing bag relieves excess pressure in the breathing bag. The speaking diaphragm, as described earlier, is built into the facepiece. .

3.6 FIRE FIGHTING PROCEDURE 3.6.1 Basic fire fighting procedures Since no two fires are exactly alike, the procedures for fighting fires must

vary to fit the circumstances. In fact, flexibility y is an important aspect of fire fighting. Often it is necessary to make split-second changes in techniques or methods of extinguishing a fire, as the fire can change its pattern.

Basically, there are certain things that must be determined before you can attack any fire. These include finding answers to the following questions: Where is the fire? What is burning? What class of fire is it? What is the extent of the fire? Does it involve more than one type of combustible material? What other combustible materials are located nearby? What special problems will exist if they catch fire?

Acting on information as to the location and nature of the fire, the scene leader makes a quick survey to determine what methods and equipment should be used to extinguish the fire. The scene leader must also make decisions concerning the need for additional men and equipment to combat the fire.

Once the location, nature, and extent of the fire have been determined, a fire area is established in which all safety precautions must be observed and from which all combustible materials must be removed. Within the boundaries of the fire area, doors, hatches, manholes, ventilation ducts, and other openings are closed where practicable and necessary. The scene leader also directs the de-energizing of electrical circuits.

The selection of agents and equipment to extinguish a fire is based upon a number of factors. These include the availability of equipment and the effects of

Figure 18 Airflow system

the various agents. The various fire-fighting agents perform as follows: Water wets, penetrates, and cools; water fog wets, cools, and shields; aqueous film forming foam (AFFF) smothers permanently; CO2 smothers temporarily; while two agents, dry chemical PKP and Halon 1301, interfere with combustion to give the effect of temporary smothering.

The agents and equipment used to extinguish various kinds of fires are listed, in the preferred order of use, in the following paragraphs:

- CLASS A fires in woodwork, bedding, clothing, and similar kinds of combustibles:

(1) fixed water sprinkling, (2) high-velocity fog, (3) solid water stream, (4) AFFF, (5) PKP, (6) CO2 extinguishers, (7) Halon 1301.

- CLASS A fires in explosives or propellants: (1) magazine sprinkling, (2) AFFF, (3) solid water stream or high-velocity fog.

- CLASS B fires in paints, spirits, and flammable liquid stores: (1) fixed CO2 installation, (2) AFFF, (3) installed sprinkling system, (4) PKP, (5) high-velocity fog, (6) portable CO2 extinguishers, (7) Halon 1301.

- CLASS B fires in gasoline: (1) installed (fixed flooding) CO2 systems, (2) TAU, (3) AFFF, (4) PKP, (5) water sprinkling system, (6) Halon 1301.

- CLASS B fires in fuel oil, JP-5, diesel oil, and kerosene: (1) installed CO2 systems (fixed flooding), (2) AFFF, (3) PKP, (4) water sprinkling system, (5) high-velocity fog, and (6) Halon 1301.

- CLASS C fires in electrical and electronic equipment (after de-energizing affected circuits):

(1) portable CO2 extinguishers or CO2 hose-and-reel systems, (2) Halon 1301,

(3) PKP, (4) high-velocity fog (no closer then 4 feet).

- CLASS D fires incombustible metals: (1) jettison into the sea, if possible, (2) high velocity fog (in quantity).

Approach the fire from the windward side, if possible. Insert the applicator fog head into the burning end of the flare and, with a slight oscillating motion, wash the burning face from the nonburning candle grain. DO NOT use a solid stream of water.

If one flare or several have ignited in a pile of flares, you will have about 1 minute before the other flares ignite. Separate the flares so that the burning ones can be extinguished individually. Fire axes, rakes, forcible-entry tools, or even the applicator itself can be used to separate the flares.

Rapid action is vitally important in fighting a flare fire, particularly below decks or in confined spaces. Water applied to a magnesium fire liberates hydrogen gas, which is violently explosive in certain concentrations. The faster the flare fire can be extinguished, the less danger there is of a hydrogen gas explosion.

3.6.2 Preventing the spread of fire Preventing the spread of a fire is a vital part of shipboard fire fighting. It is

a job that must be undertaken simultaneously with the job of fire extinguishment. A fire that is properly contained so that it cannot spread is well on the way to being controlled.

Various techniques may be used to keep a fire from spreading. Sometimes it is possible to set up a fire barrier of fireproof materials. In many situations you will have to establish fire barriers by keeping combustible materials in the area cooled with water. When particularly dangerous combustible materials such as gasoline or explosives are located nearby, you should remove them from the fire area. The bulkheads, decks, and overheads adjacent to a fire should be cooled with water to prevent the spread of fire by conduction or radiation. This cooling will also help to keep the structures from being weakened and distorted by the heat of the fire. Sometimes it may be necessary to fill adjacent compartments with CO2 to keep the fire from spreading to combustibles in those compartments.

One of the most important phases of preventing the spread of fire has to do with the correct operation and maintenance of the ship's ventilation systems. The question of whether or not to secure the ventilation system during firefighting operations depends upon the particular circumstances existing at the time. It is important to remember, however, that any ventilation system can provide a means by which a fire can rapidly spread from one compartment to another, or from one area of the ship to another.

The danger of a fire spreading through the ventilation system is particularly great if there is dirt or dust in the duct work, on the screens, or in any other part of the ventilation system. Therefore, it is very important to make sure

that the ventilation systems are inspected regularly and cleaned as often as necessary. A regular ventilation system cleaning schedule should be established and followed aboard ship. Vent ducts, heaters, screens, grease filters, flame arrestors, laundry filters, and all other parts of the ventilation systems must be kept clean. Vacuum cleaners, brushes, and low-pressure compressed air may be used to loosen and remove dirt from ducts, vents, heaters, and screens. Flame arrestors, grease filters, and laundry filters may be washed with a dishwashing compound and then rinsed with warm water.

3.6.3 Overhauling the fire After a fire has been extinguished, it must be overhauled. This is done to

make sure that it will not start burning again (reflash). The general procedures for overhauling a fire include breaking up the combustible materials with a fire axe or a fire rake and cooling the fire area with water or fog. Since many fires can flare up again after they appear to be out, it is necessary to set a reflash watch after a fire has been extinguished.

Desmoking After a fire has been definitely extinguished and overhauled, it is usually

necessary to desmoke the compartments involved. This is done by natural or forced ventilation. However, before any ventilation is undertaken, you must observe the following precautions:

1. Be SURE that the fire has actually been extinguished, and that the atmosphere tests for oxygen and explosive gases are completed and acceptable results obtained.

2. Investigate the ventilation systems to the affected areas to be sure they are free of burning or smoldering materials.

3. Have fire parties and equipment standing by the blower and controller of the ventilation systems.

4. Obtain permission from the engineer officer to open ventilation system closures and to start the blowers required to desmoke the compartments involved. You need to decide whether to use exhaust systems or supply systems for

desmoking. If supply systems are used to ventilate interior spaces, smoke and fumes are usually forced into adjacent spaces. Spaces directly open to the weather can be cleared by supply systems without any particular problem.

Portable electric or pneumatic (air) ventilating blowers can be used for desmoking, although they are not as efficient or convenient as installed ventilating systems. However, when explosive vapors or fumes are present, it may be dangerous to use installed ventilation systems. Under these circumstances, portable ventilating blowers are usually used.

Dewatering One of the special hazards of fire fighting aboard ship is that it is possible

to sink the ship while putting out the fire. It is of vital importance to remember that

all water pumped into the ship must be drained or pumped out again; this must be done rapidly enough to prevent a critical impairment of the ship's stability. Remember, flooding water has the same effect on stability, whether it enters the ship by accident or by intent. The effect of water used for fire fighting can be just as disastrous as the effects of water entering through holes in the hull. This is especially true when you are fighting fires in spaces that are high in the ship. In either case, flooding must be controlled promptly and efficiently.

Dewatering should be done according to the ship's stability and loading diagram. Loose water (that is, water with a free surface) and water located high in the ship should be removed first. Compartments that are solidly flooded and are low in the ship are generally dewatered last. An exception is when the flooding is sufficiently off-center to cause a serious list. Compartments must always be dewatered in a sequence that will contribute to the overall stability of the ship. For example, a ship could be capsized if solidly flooded compartments low in the ship were dewatered while water still remained in partially flooded compartments high in the ship.

Submersible Pumps The portable submersible pump (Fig. 19) used aboard naval ships is a

centrifugal pump driven by a water-jacketed constant speed AC or DC electric motor.

Figure 19 AC portable electric

submersible pump Figure 20 Tandem connections for

submersible pumps.

Basket strainers are always used with submersible pumps when flood water is being pumped. To dewater a compartment with a submersible pump, lower the pump into the water using the attached nylon handling line and lead discharge hose to the nearest point of discharge. The amount of flooding water taken from a flooded space increases as the discharge head decreases. Therefore, dewatering is accomplished most efficiently if the water is discharged at the lowest practicable point and if the discharge hose is short and free from kinks. When it is necessary to dewater against a high discharge head, you can use two submersible pumps in tandem (series) as shown in Figure 19 The pump at the lower level lifts water to the suction side of the pump at the higher level. A multiple outlet box is provided for making the necessary electrical connections.

When using a submersible pump, always lower it and raise it by the nylon handling line and NOT by the electric cable. Handling the pump by the electric cable could break the watertight seal where the cable enters the housing. The handling line is secured to the pump housing through an eye installed for that purpose. It may be married to the power cable (tied together), provided considerable slack is left in the cable at the pump end.

Submersible pumps are not designed to pump gasoline or heavy oil. Since the pumped liquid circulates around the motor as a coolant, gasoline can leak into the motor and cause an explosion. If you use a submersible pump to pump heavy oil, the motor will burn out because the viscous liquid will impose a heavy load on the motor. Also, a heavy, viscous liquid will not dissipate heat rapidly enough to keep the motor cool. Use the following questions as a checklist to make sure that submersible pumps are in good operating condition and ready to be used:

• Is the handling line properly secured to the eye of the pump? • Is the motor casing watertight? This point should be checked by testing

the pump with air pressure. Do not wait until the pump is needed for emergency operations; check it out ahead of time. (Have an Electrician's Mate assist you in this check.)

• Are the foot valves equipped with washers and gaskets? • Is a strainer mounted on the pump? A basket strainer can easily be made

from number 3 mesh screen wire. • Is a spare basket strainer kept at each repair party locker? • Is the discharge fitting cap in place? • Is the cable stuffing tube properly packed? (Have an Electrician's Mate

check the cable stuffing tube.) • Is a portable multiple outlet box provided at each repair party locker? • Are the necessary spanner wrenches provided for removing and replacing

strainers and for making hose connections? Observe the following safety precautions when the pump is being placed

in operation and when it is actually in use: • Keep the handling line, the electric cable, and the discharge hose clear so

that the pump can be removed quickly. . Keep the hose free of kinks. • Always use a basket strainer.

• Keep the suction end of the pump or the end of the suction hose in water while the pump is operating.

• Keep the strainer clean and free of debris. • NEVER use an electric submersible pump or any other apparatus that

might produce a spark if you are pumping where explosive vapors may be present. Ensure that the discharge flow is unrestricted.

• A qualified electrician is the only person of an emergency repair party authorized to energize or de-energize an electric submersible pump. Eductors

Eductors are jet-type pumps that contain no moving parts. An eductor moves liquid from one place to another by entraining the pumped liquid in a rapidly flowing stream of water (Venturi effect). The eductor can perform low-head dewatering operations at a greater rate of discharge than can be obtained by straight pumping with available emergency pumps. Educators are used to pump liquids that cannot be pumped by other portable pumps. Also, liquids that contain fairly small particles of foreign matter can be pumped by using an eductor. Since the operating medium of an eductor is water under pressure, portable eductors can be actuated by the ship's firemain pressure hose to the nearest fireplug and to the eductor (Fig. 21).

Figure 21 Eductor connected to firemain.

Figure 22. Pump and eductor rigged for dewatering a flooded compartment.

You must remember that not all of the eductor discharge comes from the compartment being dewatered.

Eductors can be permanently installed and activated by opening a firemain valve, or they can be rigged as required to dewater a compartment or space. They are often used with the pump to dewater compartments. Figure 5-17 shows one arrangement that could be used. In this arrangement, both the pump and the eductor are removing water from the flooded compartment.

When using an eductor for dewatering, remember that the pressure of the water supplied for the operation of the eductor must always be substantially higher than the pressure against which the

eductor is required to discharge. If this requirement is not met, the water supplied for operation of the eductor will merely back up through the eductor and assist in the flooding of the compartment. A simple rule to follow is that the pressure of the water supplied for operation of the eductor must be at least three times the static

Figure 23 Portable eductors.

head pressure against which the eductor must discharge. Two types of eductors (Fig. 23) are available for shipboard use. One is known as the S-type or single-jet eductor. The other is known as the perijet eductor. The S-type or single-jet eductor is used for dewatering and also for supplying the pump. The perijet eductor (Fig. 24) is actuated by six jets.

The following points should be kept in mind when you use an eductor:

• Be sure that the actuating pressure is AT LEAST three times the static head pressure against which the eductor must discharge.

• Keep the supply and the discharge hoses free of kinks.

• If it is necessary to use a suction hose with a perijet eductor, ensure that you use a hard rubber hose.

• Charge the eductor only when it is fully submerged.

• Keep the eductor fully submerged while operating it.

3.7 PRECAUTION FOR USE OF FIXES INSTALLATION In this chapter is presentation the location, design and operation of

shipboard fire-fighting systems to include fireman, aqueous film-forming foam (AFFF), magazine sprinkler, installed carbon dioxide (CO2), and Halon systems. To fight fires onboard ship effectively, damage control personnel must not only be very familiar with the primary damage control equipment but must also be knowledgeable of fire-fighting systems onboard ships. This chapter provides general information about fire-fighting systems. Detailed information is contained in the manufacturer’s technical manual for each system.

3.7.1 Fire main systems The fire main system receives water pumped from the sea. It distributes

this water to fireplugs, sprinkling systems, flushing systems, machinery cooling-water systems, washdown systems, and other systems as required. The fire main system is used primarily to supply the fireplug and the sprinkling systems; the other uses of the system are secondary.

Figure 24 Cross-sectional view of perijet eductor

chamber.

Figure 24 A fire-main system A. Types of fire main systems The ships have three basic types of fire main systems. They are as

follows: 1. The single-main system 2. The horizontal loop system 3. The vertical offset loop system The type of fire main system in any particular ship depends upon the

characteristics and functions of the ship. Small ships generally have a straight-line, single-main system. Large ships usually have one of the loop systems or a composite system, which is some combination or variation of the three basic types. The design of the three basic types of fire main systems is as follows:

1. The single-main fire main system shown in Figure 25 consists of a single piping run that extends fore and aft. This type of fire main is generally installed near the centerline of the ship, extending forward and aft as far as necessary.

2. The horizontal loop fire main system shown in Figure 26 consists of two single fore-and-aft, cross-connected piping runs. The two individual lengths of piping are installed in the same horizontal plane (on the same deck) but are separated athwart ships as far as practical.

3. The vertical offset loop fire main system shown in Figure 27 consists of two single piping runs, installed fore-and-aft in an oblique (that is, angled) plane, separated both vertically and athwart ship, connected at the ends to form a loop. The lower section of the fire main is located as low in the ship as practical on one side, and the upper section is located on the damage control deck on the opposite side of the ship. Athwart ship cross-connects are usually provided at each pump riser. A commonly used variation is a composite fire main system that consists of two piping runs installed on the damage control deck and separated athwart ships. A bypass section of piping is installed at the lower level near the centerline. Cross-connections are installed alternately between one service piping run and the bypass piping.

Figure 25 Single-main fire main system.

Figure 26 Horizontal loop fire main system.

Figure 27 Vertical offset loop fire main system. B. Magazine sprinkler systems Sprinkler systems are used for emergency cooling of, and fire fighting in,

magazines, ready-service rooms, ammunition and missile handling areas. A magazine sprinkler system consists of a network of pipes. These pipes are secured to the overhead and connected by a sprinkler system control valve to the ship’s fire main system. The pipes are fitted with spray heads or sprinkler-head valves. They are arranged so the water forced through them showers all parts of the magazine or ammunition and missile-handling areas. Magazine sprinkler systems can completely flood their designated spaces within an hour. To prevent unnecessary flooding of adjacent areas, all compartments equipped with sprinkler systems are watertight. Upper deck handling and ready-service rooms are equipped with drains that limit the water level to a few inches. The valves that control the operation of the magazine sprinkler system are as follows:

1. The manual control valve. This valve permits hydraulic operation of the sprinkler valve.

2. The hydraulically operated remote control valve. This diaphragm operated globe type valve is opened by operating pressure acting against the underside of the disk and closed by operating pressure acting on top of the diaphragm. This valve permits the sprinkler valve to be secured from other stations, whether or not it was manually or automatically actuated.

3. The spring-loaded lift check valve. This spring-loaded, diaphragm operated, lift check valve closes tightly against the reverse flow and opens wide to permit flow in the normal direction. Spring-loaded lift check valves permit the control system to be operated from more than one control station by preventing backflow through the other stations.

4. The hydraulically operated check valve. This valve permits the operating pressure to be vented from the diaphragm chamber of the magazine-sprinkling valve, thereby permitting that valve to close rapidly and completely.

5. Power operated check valve. This piston operated poppet type valve is opened by pressure from the “close” loop of the actuating pressure acting against the piston.

However, personnel in the Damage Controlman rating must consider what effect their maintenance or repair on the fire main system will have on the magazine sprinkler systems.

Figure 28 A sprinkler system

3.7.2 Installed aqueous film-forming foam (AFFF) system Aqueous film-forming foam (AFFF) is one of the most widely used fire-

fighting agents. AFFF is primarily used aboard ship to fight class BRAVO fires, often in conjunction with Purple-K-Powder (PKP). AFFF is delivered through both portable and installed equipment. Two types of installed AFFF systems are shown in figures 29 and 30.

Figure 29 Typical two-speed AFFF system.

Components The primary components and associated equipment of a shipboard AFFF

system include the following: • AFFF Generating Equipment - Installed AFFF generating equipment is

usually located in main machinery spaces. The reason for this is that research has revealed that these are the places where class Bravo fires most often occur. There are two types of pumps used with the installed AFFF system. They are the AFFF single-speed injection pump and the AFFF two-speed injection pump.

• AFFF Single-Speed Injection Pump. The AFFF single-speed injection pump is a permanently mounted, positive displacement, electrically driven, sliding-vane type of pump. The pump unit consists of a pump, a motor, and a reduction gear, coupled together with flexible couplings and mounted on a steel base. The pump is fitted with an internal relief valve,

which opens to prevent damage to the pump. The injection pump and the injection station piping are sized to produce a 6 percent nominal concentration at peak demand by injecting AFFF concentrate into the seawater distribution system. AFFF concentrate is supplied from an AFFF tank. This hose connection is used to transfer AFFF concentrate to other tanks by connecting hoses between the pump and fill lines of the other tank. AFFF is transferred by manually starting the injection pump that is used to supply the wash down countermeasure system with AFFF. Besides washdown countermeasure systems, injection pumps also supply AFFF to reentry hose reels, well decks, and fueled vehicle stowage decks.

Figure 30 Typical high capacity single-speed pump system.

• AFFF Two-Speed Injection Pump. The AFFF two-speed injection pump is designed to meet the demand for either a low or a high fire-fighting capability. The two-speed AFFF pump consists of a positive displacement pump rated at 175 psi, a motor, and a reducer, coupled together with flexible couplings and mounted on a steel base. The pump is designed to inject AFFF concentrate into the seawater supply at a constant flow rate, depending on the pressure and demand of fire-fighting requirements. AFFF concentrations will exceed 6 percent in most cases. The low-speed mode is used for individual AFFF demand hose reel stations. The motor on the two-speed pump receives power from a motor controller supplied by a power panel that receives main ship’s power from both the ship’s service switchboard and the emergency service switchboard. The power panel is equipped with an automatic bus transfer (ABT) to ensure a constant supply of electrical power to the two-speed pump. The motor controller has provisions for both local and remote control. From the local control station, the pump can be started at either high or low speed. Remote control stations are segregated into high and low demand stations. High demand stations, such as that for a hangar bay sprinkler system, start the pump at high speed. Low demand stations, such as that for a hose reel, start the pump at low speed. When the system is being secured, you can only stop the pump at the local control station.

• AFFF Transfer Pumps. The AFFF transfer pump is a permanently mounted, single-speed, centrifugal type, electrically driven pump. These pumps are provided in 360-gpm capacity. The transfer pump moves AFFF concentrate through the AFFF fill-and-transfer subsystem to all AFFF station service tanks on a selective basis.

• AFFF Tanks. The tanks are rectangular or cylindrical in shape and are fabricated out of 90/10 copper-nickel or corrosion-resistant steel. Each service tank is located inside the AFFF station and is fitted with a gooseneck vent, drain connection, fill connection, liquid level indicator, recirculating line, and an access manhole for tank maintenance. The gooseneck vent prevents excess buildup of pressure within the tank during storage and prevents a vacuum when the system is in operation.

• AFFF Valves The AFFF system requires a variety of valves with different functions. These valves include the following:

o Powertrol valve o Powercheck valve o Powertrol valve with test connection o Hytrol valve o Hycheck valve o Solenoid-operated pilot valve o Balancing valve o Balanced pressure proportioner (Type II) o Balanced pressure proportioner (Type III)

• Balanced Pressure Proportioner (Type II) The Type II balanced-pressure proportioner, proportions the correct amount of AFFF concentrate

necessary to produce effective AFFF/seawater solution over a wide range of flows and pressures. The system is actuated by activating an SOPV, electrically or manually. The SOPV will vent the operating chamber of the hycheck valve and pressurize the operating chamber of the powertrol valve. The switch assembly of an SOPV will cause electrical activation of the pump assembly (positive displacement, sliding vane, or rotary gear) via the motor controller. The pump assembly will pressurize the AFFF concentrate piping to the demand proportioned and balancing valve. Water flow through the proportioner will move the water float towards the large opening of the water sleeve, depending on the number of gallons required for fire fighting. The AFFF concentrate flow is directly controlled by the movement of the water float, thus influencing the amount of AFFF concentrate that enters the water stream.

• Balanced Pressure Proportioner (Type III) The purpose, actuation of system, and balancing valve theory for the Type III balanced-pressure proportioner, are identical to those of the Type II proportioner . The Type III proportioner houses no internal moving parts and uses the venturi principle to allow for complete mixing of AFFF/sea water solution. An orifice plate controls the volume of gallons of AFFF concentrate entering the proportioner. The size of the orifice is determined by the maximum demand for fire-fighting agent placed on the system. The water -sensing line connection for the Type III proportioner is piped directly from the proportioner body to the balancing valve. Type III proportioner systems use a positive displacement, sliding vane pump.

• AFFF Sprinkler System. Sprinkler systems are a convenient and quick method for the fire party to apply AFFF/water solution or water to large areas of burning fuel. The system consists of a large header pipe with smaller branch connections and attached sprinkler heads. A sprinkler group control valve (powertrol or hytrol with test connection) will control the discharge flow to the sprinkler heads. An SOPV or a manual control valve may actuate the group control valve. Some sprinkler systems are activated by a manually operated cutout valve. Actuation controls for the group control valves may be located in primary flight control, the navigational bridge, the helo control, a conflagration station, locally at the AFFF generating station, and at various locations throughout the ship, depending on the sprinkler system installation and type of ship. An AFFF sprinkler system is a subsystem of AFFF generating systems. Some of the different types of sprinkler systems aboard naval ships are listed below.

o The bilge sprinkling system is located in the main and auxiliary machinery spaces with the sprinkler heads installed below the lower level deck plates. Overhead sprinkling is installed in the overhead of helo and hangar bays, well decks, vehicle cargo holds, and fuel pump rooms. Some diesel-powered ships have the overhead sprinkler system installed in the main machinery space.

o The flush-deck system uses the countermeasure wash down flush-deck nozzles to discharge AFFF/water solution during flight deck and helo deck fires. This capability is currently available to all aircraft carriers, helicopter carriers, and some auxiliary and combatant ships.

o The deck-edge sprinkler sprays AFFF/water solution over the flight deck of aircraft carriers and helicopter carriers. The system consists of spray nozzles that are positioned at the deck-edge combing of the port and starboard sides on helicopter and flight decks. The nozzles project the AFFF/water solution across the deck in an arc pattern to spray over the top of the burning fuel and aircraft.

Figure 31 Use of low-expansion foam

• AFFF Transfer System. AFFF generating stations use large volumes of AFFF concentrate during fire fighting. The service tank alone may not contain enough concentrate to combat a conflagration-type fire. Transfer capabilities are available to replenish the AFFF concentrate service tanks. The installed system consists of a reserve transfer pump (positive displacement, sliding vane, or centrifugal), reserve storage tanks, and associated piping and valves. The transfer system can deliver AFFF concentrate to on-station service tanks via a transfer main. The transfer main consists of a large pipe with smaller branch connections interconnecting the AFFF service and storage tanks. This feature gives the on-station concentrate pump the capability of delivering AFFF concentrate into the transfer main. Once the transfer main is pressurized, either by the reserve pump or by the on-station pumps, all AFFF generating station service tanks can be replenished. On-station pumps used in conjunction with jumper hoses and hose connection valves may be used to transfer AFFF concentrate.

• AFFF Testing Equipment. AFFF concentrate and AFFF/seawater solution must be tested periodically to ensure that the fire party has an effective agent to combat class BRAVO fires. To accomplish the test, you must have a basic understanding of the equipment used to conduct the test. The testing equipment includes the hand refractometer and the quantab chloride titrator strip. 3.7.3 Installed carbon dioxide (CO2) systems Carbon dioxide (CO2) is a colorless, odorless gas that is naturally present

in the atmosphere at an average concentration of 0.03 percent. It is used for extinguishing fires because it reduces the concentration of oxygen in the air to the point where combustion stops. Typically, CO2 concentrations of 30 to 70 percent are required to extinguish fires. Carbon dioxide extinguishers are installed in naval ships to provide a dependable and readily available means to flood (or partially flood) certain areas that present unusual fire hazards. An installed CO2 extinguishing system has one or more cylinders. The cylinders may be installed singly or in batteries of two or more. Except for their size and releasing mechanisms, the portable cylinders are essentially the same as the portable cylinders. The two types of installed CO2 systems are the CO2 hose-and-reel installation and the CO2 flooding system. The CO2 flooding system is used for spaces that are not normally occupied by personnel.

History of Carbon Dioxide Fire Extinguishing Systems Carbon dioxide systems have been in use since the early 1900’s and in

the late 1920’s work began on the first NFPA standard describing the use of these systems. From that point until the late 1960’s, carbon dioxide was for all practical purposes the only gaseous extinguishing agent in wide commercial use. It was during that time period that society apparently became accustomed to the notion that employing a fire extinguishing system with inherent serious life safety

consequences was nothing more than a trade-off and well worth the risk in light of the fire protection benefits derived.

In the early 1970’s carbon dioxide total flooding systems somewhat fell from favor with the introduction of the halons and specifically halon 1301 systems. Halon 1301, with its inherent life safety characteristics coupled with the fact that the new systems were less expensive than high pressure carbon dioxide systems, virtually left carbon dioxide fewer and fewer places to be applied. During the period of the early 1970’s until the late 1980’s, the use of carbon dioxide systems was relegated to applications where (1) halon 1301 was clearly inappropriate or where (2) the promoters of halon 1301 chose not to market that agent. The most obvious of these were local application systems, an area never seriously pursued with halon 1301; applications with a deep seated Class A fire potential, like shipboard cargo holds; and applications where decomposition of halon 1301 would be problematical, like in ovens. Another area virtually reserved for carbon dioxide in that time frame were applications that needed so much agent that refrigerated, bulk storage, low pressure carbon dioxide systems were the economical choice.

In general, a good rule of thumb was if you are going to experience a lot of system discharges, it was wiser to invest in a carbon dioxide system where the cost of recharge was much less than that of a halon 1301 system. Otherwise, if the fire extinguishing system was employed to protect high value hazards with a low probability of fire, the lower initial cost, safer halon 1301 system became the preferred selection.

With the 1994 production and import ban on newly produced halons and even with the introduction of new halon alternatives, we have seen an increase in the use of carbon dioxide fire extinguishing systems, especially in the marine market. The resurgence in the use of carbon dioxide in the marine market is very visible since shipbuilding is a huge market for fire protection systems and the procurements and buying preferences are apparent. In other markets, such as industrial and commercial, changes in carbon dioxide system preferences and usage is not that obvious.

Carbon Dioxide Performance in Marine Systems In trying to quantify the historical performance of carbon dioxide systems,

it was found that statistics are just not available. However, it was possible to derive a sense of the performance by looking at the marine market and searching the Lloyd’s List casualty archive14 for shipboard engine room incidents of fire involving carbon dioxide systems.

The search covered the period from January 1991 through November 2002 and identified 56 articles describing the same number of fire incidents within the scope of the search parameters. Some of the articles were better than others with respect to providing meaningful information. Table 3 is an illustration of the information derived from the articles. Appendix A contains an expanded table summarizing the individual incidents.

In reviewing the information in Table 3., unless the Lloyd’s List casualty archive misses most or even many of the engine room fires and related carbon

dioxide system releases, 56 discharges of engine room systems over a period of 12 years is less than five per year.

Table 3 is an illustration of the general circumstances surrounding these accidents, clearly illustrating that maintenance activities – either on the system or in the vicinity of the system – are mostly associated with these incidences of system discharges.

Types of Carbon Dioxide Extinguishing Systems Carbon dioxide systems can best be categorized by agent storage

configurations and methods of applications. Agent Storage Configurations There are two configurations for storing the agent in carbon dioxide

systems: either high pressure or low-pressure storage. The type of storage container does not have a bearing on the relative safety of the agent. It does have an effect on the economics of a system, especially in large systems protecting multiple hazards where the low-pressure, and lower cost, approach is often preferred. Descriptions of these two agent storage configurations are available in many documents.

Methods of Application. There are two common methods for applying carbon dioxide extinguishing

agent: (1) total flooding and (2) local application. The method of application does have an effect on the relative safety of the system. While injury and death are always possible with either method if people become exposed to the agent in high concentrations, the popular belief is that escape from the vicinity of a local application system discharge is more likely than escape from an enclosed space during or after a total flooding system discharge.

Total Flooding Systems working on a total flooding principle apply an extinguishing agent

to an enclosed space in order to achieve a concentration of the agent (volume percent of the agent in air) sufficient to extinguish the fire. These types of systems may be operated automatically by detection and related controls or manually by the operation of a system actuator.

Total flooding is the most common system application of carbon dioxide in the marine sector with the protection of machinery spaces, machinery space control rooms, cargo pump rooms and dry cargo spaces. Total flooding is also done in many industrial applications such as diesel generator rooms, cable spreading rooms, electrical switchgear rooms and similar spaces. Carbon dioxide total flooding systems are sometimes used to protect the sub-floor spaces in computer or computer like facilities.

Table 3 Search Results Shipboard Engine Room Fires and Carbon Dioxide Systems, (January 1991 through November 2002)

Table 4 Causes of Injuries and Deaths Associated with Carbon Dioxide Discharges (1975 - 1999)

Local Application In local application, the agent is applied directly onto a fire or into the

region of a fire. This is perhaps the most significant use of carbon dioxide as the

techniques and guidelines for applying other gaseous agents in this manner simply have not been developed. Local application carbon dioxide systems are used in numerous industrial applications including aluminum rolling mills, printing presses, dip tanks, quench tanks and similar applications.

There are two different techniques used to design local application systems.

Rate by-Area Method The area method of system design is used where the fire hazard consists

primarily of flat surfaces or low-level objects associated with horizontal surfaces. In these applications, nozzles are usually located in one plane either in a tank-side or overhead configuration. The agent is applied within flow rate and area coverage limitations established in listing and approval testing programs.

Rate-by-Volume Method The volume method of system design is used where the fire hazard

consists of three-dimensional irregular objects that cannot be easily reduced to equivalent surface areas. In this case, the system is designed on the basis of an assumed enclosure surrounding the three dimensional hazard. The agent is applied to meet a minimum proscribed flow rate density (kilograms per second per cubic meter of assumed volume) and within the flow rate and area coverage limitations established in listing and approval testing programs.

Mechanism of Extinguishment. The extinguishing mechanism of carbon

dioxide is primarily dilution of the oxygen content of the atmosphere surrounding a hazard to a point where that atmosphere will no longer support combustion. Under certain applications, the available cooling effect is also helpful especially where carbon dioxide is applied directly on the burning material.

Marine Market The marine market is a large user of carbon dioxide systems and that use

has been increasing with the halt of production of halon 1301. Table 5. is an illustration of the more common applications of carbon dioxide total flooding systems in marine applications.

As shown in Table . most of the applications are in normally unoccupied spaces but, of those, most would also have people accessing the space for service, maintenance, loading, unloading or other purposes.

Table 6 is an illustration of the agents that are in use today which achieve the same technical level of performance as the carbon dioxide systems for the marine applications. The alternatives shown in Table 6 are not in any order of preference as there is a significant difference between USCG and international requirements where some agent systems are permitted and others are not, thus making ranking quite difficult.

While it may be interesting to review all these different spaces on the ships now being protected by carbon dioxide, the number one priority must be the examination of the spaces that are normally occupied by people. Those are

the main machinery spaces. In discussions with the delegates to the International Maritime Organization Fire Protection Sub-Committee (47th Session of the Fire Protection Sub-Committee, International Maritime Organization, London, UK: February 10-14, 2003) there was general agreement that the order of preference of systems for the protection of machinery spaces on SOLAS regulated ships is:

o • Carbon dioxide systems o • High expansion foam systems o • Water mist or spray systems o • Halocarbon systems o • Inert gas systems

Table 4 Marine Applications for Carbon Dioxide Total Flooding Systems

Table 5 Alternatives to Marine Carbon Dioxide Total Flooding Systems (Alternatives listed in alphabetical order)

The listing of the preferences on SOLAS ships is, with the exception of

water mist, in ascending order of system cost with carbon dioxide being the least expensive, high expansion foam next, etc. It will be shown later in this report (section 11) that water mist systems are generally the most expensive alternatives to carbon dioxide at small volumes but become the least expensive at larger volumes, perhaps accounting for the ranking of that type system in the middle of the list of preferred systems.

However, the order of preference on US flag commercial vessels is somewhat different since the USCG has not approved any water mist, water spray or high expansion foam systems for total flooding protection of machinery spaces. Thus, in the US, the current preferences are in this order which, as will be shown later in section 11, is in ascending order of system cost:

o Carbon dioxide o Halocarbon systems (specifically FM-200)28 o Inert gas systems (specifically Inergen)

In discussing the matter of system preferences with IMO delegates, some believe that the use of carbon dioxide systems tends to fall off in smaller vessels where agent storage container space and weight of the system become more of an issue. The estimate for the smaller ships is that 7 out of 10 are using carbon dioxide systems; however, as will be shown later, the US information shows over 8 out of 10 new commercial ships being built today are being fitted with carbon dioxide systems.

International Standards Organization requirements for carbon

dioxide systems ISO Standard 618358 for carbon dioxide fire extinguishing systems was

first published in 1990 and has not been revised since. The following as its scope:

Scope This International Standard lays down requirements for the design and

installation of fixed carbon dioxide fire-extinguishing systems for use on premises. The requirements are not valid for extinguishing systems on ships, in aircraft, on vehicles and mobile fire appliances or for below ground systems in the mining industry, nor are they valid for carbon dioxide pre-inerting systems.

Appendix F is an excerpt of the requirements and related explanatory material regarding safety requirements, including:

o exit routes o warning and instruction and direction signs o alarms o outward swinging self-closing doors o self-contained breathing equipment o personnel training o ventilation of the areas after extinguishing the fire

The standard has specific requirements for: o precautions for low-lying parts of protected areas. o • precautions during maintenance work.

International Maritime Organization requirements for carbon dioxide

systems The requirements for carbon dioxide systems that are employed on ships

on international voyages fall under the regulations promulgated by the International Convention for the Safety of Life at Sea, 1974, an international ship safety treaty, also referred to as SOLAS. Those requirements are detailed in the Fire Systems Safety Code (FSS Code International Code for Fire Safety Systems, Chapter 5, Fixed Gas Fire Extinguishing Systems,” International Maritime Organization, 4 Albert Embankment, London SE1 7SR, England: July 2002) which has the following stated purpose: “The purpose of this Code is to

provide international standards of specific engineering specifications for fire safety systems required by chapter II-2 of the International Convention for the Safety of Life at Sea, 1974, as amended.”

An excerpt from this Code pertaining to the safety requirements for carbon dioxide systems is shown at Appendix G. In general, though, the requirements are rather simple, covering the following:

• A requirement to prevent inadvertent release of the agent into the space together with guidelines about routing piping for the systems through accommodations or passenger spaces.

• A requirement for a predischarge alarm and time delay of at least 20 seconds to permit personnel evacuation from “Ro-Ro spaces and other spaces in which personnel normally work or to which they have access.” Conventional cargo spaces and “small spaces” are exempted from these requirements.

• A requirement that the controls for of any fixed gas fire-extinguishing system have clear instructions relating to the operation of the system having regard to the safety of personnel.

• The requirement that all systems must be manually operated. That is, automatic release of the fire-extinguishing system is not permitted.

• Plus the requirement that carbon dioxide systems must have two separate controls, one control for opening the valve of the piping which conveys the gas into the protected space and a second control for opening the valve on the agent storage containers.

• Concern over the use of carbon dioxide systems has been expressed at the 47th meeting of the IMO Fire Protection Sub-Committee in February 2003 where three documents were submitted on this subject.

• First, a report (Report of the Correspondence Group on Performance Testing and Approval Standards for Safety Systems,” Document FP 47/8, International Maritime Organization, 4 Albert Embankment, London SE1 7SR, England: November 2002) by the Correspondence Group on Performance Testing and Approval Standards for Fire Safety Systems that described specific tasks for a working group to accomplish. The following is a verbatim excerpt from that report and attention is called to point .9. “4” Fixed gas fire-extinguishing systems Consider revising MSC/Circ.848

for fixed gas fire-extinguishing systems, including inert gases required by regulation II-2/10.4.1.1.1 and 10.9.1.1 to:

• add the PBPK model for toxicity; • add component manufacturing standards; • define a standard cup burner test; • identify necessary changes for testing of inert gases; • decide on the need for a minimum vent opening; • harmonize the minimum fire size with MSC/Circ. 668; • correlate the volume of the test enclosure with the actual engine room

volume;

• decide if a fire exposure test should be required for agent storage containers and control system components located inside the protected space; and 9 decide if carbon dioxide should be prohibited in occupied spaces.” Second, a paper (Proposal for Amending the International Code for Fire

Safety Systems,” Document FP 47/8/1, Submitted by Denmark, International Maritime Organization, 4 Albert Embankment, London SE1 7SR, England: November 2002.) submitted by Denmark, called for changes to the requirements for carbon dioxide systems to improve their safety performance. The Danish proposal included this statement:

“4 It should also be noted that CO2 systems are still being released by accident so the safety of the personnel in the concerned spaces should have high priority in the Sub-Committee’s consideration of this matter. “

Third, a paper (Availability of Halons Used on Board Ships,” Document FP 47/INF.5, Submitted by the United States, International Maritime Organization, 4 Albert Embankment, London SE1 7SR, England: November 2002.) submitted by the United States transmitting for the information of IMO delegations a copy of the Merchant Shipping Case Study excerpt from the 2002 Assessment Report (2002 Assessment Report of the Halons Technical Options Committee,” ISBN 92-807-2286-7, Ozone Secretariat, United Nations Environment Program, Nairobi, Kenya: March 2003.) of the UNEP Halons Technical Options Committee.

The following excerpt addresses the use of carbon dioxide systems in shipboard machinery spaces:

“But a recent survey has illustrated that 9 out of 10 new ships use carbon dioxide systems for the protection of the machinery space. While systems using the new halon alternatives are safer than carbon dioxide in terms of personnel exposure to the agents, they are all more expensive than carbon dioxide systems, thus accounting for the new popularity of carbon dioxide. Irrespective of the safety devices and measures employed with total flooding carbon dioxide systems, the history of deaths and injuries caused by these systems is ample evidence that their wholesale employment will likely produce higher rates of deaths and injuries than we are currently experiencing. This regression to carbon dioxide systems has alarmed many health and safety officials. On the basis of the growing life safety concerns, it is likely there will be efforts to effect a ban on the use of carbon dioxide total flooding systems in normally occupied spaces, including shipboard machinery spaces.”

CO2 HOSE-AND-REEL SYSTEM The CO2 hose-and-reel installation (Fig. 32) consists of two cylinders, a

length of special CO2 hose coiled on a reel, and a horn-shaped nonconducting nozzle equipped with a second control valve. When the hose and reel are both installed near the normal access, each of the two cylinders may be actuated individually. Due to space limitations, cylinders may not be located near the hose reel.

WARNING:

Grooved nut discharge heads are to be installed only for CO2 hose reel installations.

They must not be installed with CO2 total flooding systems. To operate a CO2 hose-and-reel system, you should adhere to the procedure that include the steps as follows:

1. Ensure the horn valve is in the CLOSED position. 2. Open the control valve on the cylinder intended for use. 3. Unreel the hose and run the horn to the point of attack on the fire. 4. Open the horn valve by turning the lever or by depressing the squeeze

grip. 5. Direct the CO2 discharge toward the base of the fire.

Figure 32 CO2 hose-and-reel system. CO2 FLOODING SYSTEM The CO2 flooding system (Fig. 6-17) consists of one or more cylinders

connected by piping from the valve outlets to a manifold. Fixed piping leads from the manifold to various areas of the compartment to be flooded. Cables run from the valve control mechanisms to pull boxes that are located outside the compartment containing the cylinders (Sometimes, the cylinders are also located outside of the compartment to be protected). To release CO2, just break the glass in the front of the pull box and pull the handle of the cable leading to the CO2 cylinders.

There are usually one or two valve control devices in a CO2 flooding system. The number of valve control devices provided will depend on the number of cylinders in the bank. The remaining cylinders in the bank (if any) are provided with pressure-actuated discharge heads. These heads open automatically when pressure from the controlled cylinders enters the discharge head outlet.

Figure 33 CO2 flooding system. Several manufacturers make various components of the CO2 systems

installed on naval ships. These components differ in some minor details. Therefore, for detailed information on a specific installation, always consult the appropriate manufacturer’s technical manual.

CAUTION: Before operating an installed CO2 system, ensure all openings in the compartment are closed and the ventilation system for the space is secured. These precautions are necessary to prevent the loss of CO2.

Figure 34 A carbon dioxide release locfker for engine-room

Figure 35 Schematic diagram of a CO2 “total flooding” system

Increase of carbon dioxide fire-extinguishing media If a container cargo hold fitted with partially weathertight hatchway covers

is protected by a fixed carbon dioxide fire-extinguishing system, the amount of carbon dioxide for the cargo space should be increased in accordance with one of the following formulae, as appropriate:

where:

IMO AND IACS REQUIREMENTS FOR LOW PRESSURE CO2 SYSTEMS (MARITIME SAFETY COMMITTEE (MSC) 76/18/2, 27 August 2002. Original: ENGLISH. RELATIONS WITH OTHER ORGANIZATIONS. IACS

Unified Interpretations. Submitted by the International Association of Classification Societies (IACS) )

Low pressure CO2 systems (Reg.ll-2/5.2) Where a low pressure CO2 system is fitted to comply with this regulation,

the following applies: 1. The system control devices and the refrigerating plants should be

located within the same room where the pressure vessels are stored. 2. The rated amount of liquid carbon dioxide should be stored in vessel(s)

under the working pressure in the range of 1.8 to 2.2 N/mm2. The normal liquid charge in the container should be limited to provide sufficient vapor space to allow for expansion of the liquid under the maximum storage temperatures that can be obtained corresponding to the setting of the pressure relief valves but should not exceed 95% of the volumetric capacity of the container.

3. Provision should be made for: - pressure gauge; - high pressure alarm: not more than setting of the relief valve; - low pressure alarm: not less than 1.8 N/mm2; - branch pipes with stop valves for filling the vessel; - discharge pipes; - liquid CO2 level indicator, fitted on the vessel(s); - two safety valves. 4. The two safety relief valves should be arranged so that either valve can

be shut off while the other is connected to the vessel. The setting of the relief valves should not be less than 1.1 times working pressure. The capacity of each valve should be such that the vapors generated under fire condition can be discharged with a pressure rise not more than 20% above the setting pressure. The discharge from the safety valves should be led to the open.

5. The vessel(s) and outgoing pipes permantly filled with carbon dioxide should have thermal insulation preventing the operation of the safety valve in 24 hours after de-energizing the plant, at ambient temperature of 45oC and an initial pressure equal to the starting pressure of the refrigeration unit.

6. The vessel(s) should be serviced by two automated completely independent refrigerating units solely intended for this purpose, each comprising a compressor and the relevant prime mover, evaporator and condenser.

7. The refrigerating capacity and the automatic control of each unit should be so as to maintain the required temperature under conditions of continuous operation during 24 hours at sea temperatures up to 32oC and ambient air temperatures up to 45oC. (Note: This UI SC 170 is to be uniformly implemented by IACS Members and Associates from 1 January 2003).

3.7.4 Halon systems Halon is a halogenated hydrocarbon, which means that one or more of the

hydrogen atoms in each hydrocarbon molecule have been replaced by one or more atoms from the halogen series (fluorine, chlorine, bromine, or iodine). A Halon numbering system has been developed to provide a description of the various halogenated hydrocarbons. The first digit in the number represents the number of carbon atoms in the molecule; the second digit, the number of fluorine atoms; the third digit, the number of chlorine atoms; he fourth digit, the number of bromine atoms; and the fifth digit, the number of iodine atoms, if any. In this system, terminal zero digits, if any, are not expressed. The two types of Halon used aboard ships are Halon 1301 and 1211. Halon 1301 is the most commonly used type because it is installed and used in fixed flooding systems for extinguishing flammable liquid fires. Halon 1211 is a colorless gas that has a sweet smell and is known chemically as bromochlorodifluoromethane. It is used for twin agent aqueous film-forming foam (AFFF)/Halon 1211 applications on some flight and hangar deck mobile fire-fighting apparatus. Portable 20-pound Halon 1211 fire extinguishers are installed in MHC-51 class coastal minesweeping ships and air-cushion landing craft (LCAC). Halon 1211 is stored and shipped as a liquid and pressurized with nitrogen gas. Pressurization is necessary since the vapor pressure is too low to convey it properly to the fire area. Halon 1211 is not used in total flooding systems. It has a low volatility combined with a high liquid density, which permits the agent to be sprayed as a liquid. As a liquid spray Halon 1211 may be propelled into the fire zone more effectively than is possible with other gaseous agents. Halon 1211 is used in twin agent systems installed on mobile firefighting apparatus on carrier type ships. Both Halon 1211 and 1301 chemically inhibit the flame front of a fire. Halon decomposes upon contact with flames or hot surfaces above 900°F (482°C).

Decomposition products are principally hydrogen fluoride and hydrogen bromide, which have a sharp irritating odor even at low concentrations. The short discharge time of Halon 1301 (10 seconds maximum) keeps the thermal decomposition products well below lethal concentrations. However, a real hazard lies in the products of combustion from the fire such as carbon monoxide. These products combined with oxygen depletion, heat, and smoke pose a great hazard to personnel.

WARNING: Personnel should not remain in a space where Halon 1301 has been

released to extinguish a fire unless some type of breathing apparatus is worn. Most people can be exposed to a 5 to 7 percent concentration of Halon 1301 for a period up to 10 minutes without danger to their health. However, safety precautions dictate that spaces should be evacuated anytime a Halon system discharge occurs. Human exposures to both Halon 1301 and to Halon 1211 have shown that Halon 1301 concentrations up to about 7 percent by volume, and Halon 1211 concentrations of 2 to 3 percent by volume, have little noticeable effect on personnel. The CO2 flooding system is used for spaces that are

normally occupied by personnel. At Halon 1301 concentrations between 7 and 10 percent and Halon 1211 concentrations between 3 and 4 percent, personnel experienced dizziness and tingling of the extremities, indicative of mild anesthesia. At Halon 1301 concentrations above 10 percent and Halon 1211 concentrations above 4 percent the dizziness becomes pronounced, the subjects feel as if they will lose consciousness (although none have), and physical and mental dexterity is reduced. The discharge of Halon 1211 to extinguish a fire may create a hazard to personnel from the natural Halon 1211 itself and from the products of decomposition that result from the exposure of the agent to the fire or other hot surfaces. Prolonged exposure to concentrations greater than 4 percent carries with it the possible risk of unconsciousness and even death. Although Halon 1211 vapor has a low toxicity, its decomposition products can be hazardous. When using Halon 1211 in unventilated or confined spaces, operators and others should avoid breathing the gases, and should only use the agent needed to accomplish extinguishment. Although they are potentially hazardous, no significant adverse health effects have been reported from the use of Halon 1301 or 1211 as a fire-extinguishing agent since their introduction into the marketplace 30 years ago.

WARNING: In flammable gas cylinder storerooms, 20 percent Halon 1301 is required

to extinguish a fire. Therefore, if the system is activated, personnel must leave the space immediately.

Direct contact with vaporizing Halon 1301 and Halon 1211 liquid has a strong chilling effect on objects and can cause frostbite and burns to the skin. The liquid phase vaporizes rapidly during discharge and therefore limits this hazard to the immediate vicinity of the nozzle.

High velocity discharge from nozzles is sufficient to move unsecured paper and light objects, which could cause personnel injury. Discharge of a total flooding system can cause noise loud enough to be startling. In humid atmospheres, reduction in visibility may occur due to condensation of water vapor in the air. Halon 1211 and Halon 1301 are severe ozone depleting substances. These agents should be used only against actual fires. Any Halon cylinder containing only a partial charge, or is being turned in to supply, shall not be vented to the atmosphere for any reason. Halon 1301 (known chemically as bromotrifluoromethane) consists of one atom of carbon, three atoms of fluorine, no chlorine atoms, one bromine atom, and no iodine atoms. For shipboard installation, Halon 1301 is super pressurized, with nitrogen, and stored in gas cylinders as a liquid. When released, it vaporizes to a colorless, odorless gas with a density of approximately five times that of air Halon 1301 systems (Fig. 6-18). It may be installed in main machinery rooms, fire rooms, engine rooms, auxiliary machinery rooms, fuel pump rooms, ship service or emergency generator rooms, auxiliary boiler rooms, main propulsion or generator engine modules, helicopter recovery assist, securing and traversing (RAST) areas, machinery rooms, tactical towed array sonar (TACTAS) handling rooms, and in spaces where flammable liquids are stored or issued. Aboard aircraft carriers, gas-powered bomb hoist storerooms may be protected by Halon 1301.

Halon systems use one or more cylinders containing Halon 1301 in a liquid form. The function of the system is to extinguish fires that are beyond the capacity of portable fire extinguishing equipment, and where abandonment of the space is necessary.

Figure 36 Halon 1301 system. COMPONENTS The components of the Halon system include the following:

o Halon 1301 cylinders o CO2 actuators o Vent fittings

o Copper nitrogen tubing connections with a loop that are called actuation lines

o Flexible discharge hoses o Check valve o Time-delay device o Time-delay device bypass valve o CO2 actuation system piping o Pressure switches o Halon discharge piping o Discharge nozzles o In-line filter o Electrically operated alarms and indicators

Location The usual location for Halon cylinders is inside a protected compartment

within a space; however, they may be located outside or in a Halon cylinder room. Halon systems placed in machinery spaces (Main Machinery Rooms, Firerooms, Engine Rooms, Auxiliary Machinery Rooms) will have 60-second time delays. In compartments other than Machinery Spaces, Halon systems usually have a 30-second time delay, and only a primary Halon system. Engine enclosures or modules have a 30-second time delay for both primary and reserve Halon systems.

Capabilities Each system is designed so a single discharge of Halon 1301 provides a

concentration of 5 to 7 percent Halon 1301 by volume of air throughout the protected space. Sufficient Halon is required so the concentration will remain at a minimum of 5 percent for 15 minutes. Some Halon protected spaces have a duplicate reserve Halon system to supplement the primary one. Each Halon fixed-flooding system is designed to discharge completely the Halon 1301 gas into the protected space within 10 seconds following the start of the discharge.

System actuation and features Each system is usually provided with more than one CO2 actuator station.

The actuators can be installed either inside or outside the space. Features of the system include automatic ventilation shutdown, actuation of local and remote alarms, manual time delay bypass, and halon discharge indicator light.

System operation Normal operation of the halon system may be accomplished by performing

the following actions: 1. Break the glass or open the enclosure at a remote actuating stations.

Remove the safety pin, which is secured by a lead and wire seal. 2. Fully operate the discharge lever and secure it in the OPERATE

position. The released carbon dioxide will immediately actuate two pressure switches. One pressure switch operates lights and horns (or bells) within the

space, and a bell and amber system actuated light outside the space at actuating stations and space accesses. The other pressure switch will initiate shut down of ventilation fans and operate any installed vent closures.

3. If alarms do not operate, or ventilation does not shut off, pull out the reset/actuation knob on the associated pressure switch. If operation still does not occur, manually shut off ventilation systems, and pass the word to evacuate the space.

4. After the time delay operates, the carbon dioxide pressure will operate the Halon cylinder valves to discharge Halon to its associated nozzles. A third pressure switch downstream of the time delay device will then actuate a red light indicating Halon discharge.

5. In the event the timing of the time delay device exceeds 70 seconds (for a 60-second device), or 35 seconds (for a 30-second device), the time delay should be bypassed by opening the time delay bypass valve.

WARNING: The time delay bypass valve should not be operated until after the full

delay time of 30 or 60 seconds has passed. Additional features include automatic ventilation shutdown, actuation of local and remote predischarge alarms, manual time delay bypass, automatic ventilation closures (if installed), and Halon discharged indicator light. An AFFF bilge sprinkling system normally supplements Halon 1301 systems in machinery spaces and pump rooms. The AFFF bilge sprinkling system, where installed, should be actuated at the same time as the Halon system. AFFF bilge sprinkling systems are not installed if the bilge is too shallow.

3.7.5. Aqueous potassium carbonate (APC) Design components, and operation of a typical installed aqueous

potassium carbonate (APC) fire-extinguishing system. Aqueous potassium carbonate (APC) fire-extinguishing systems (Fig. 37. Aqueous potassium carbonate is specifically formulated to extinguish fire in the reservoirs by combining with the hot cooking-oil surface to form a combustion-resistant soap layer, thereby cutting off the grease from its source of oxygen. There is little or no cooling with APC. A typical APC fire-extinguishing system is shown in Fig. 37.

Components Each APC system includes one or two cylinders filled with a solution of

potassium carbonate in water pressurized with compressed nitrogen (N2). Discharge piping from the cylinder(s) leads to one or more nozzles which spray the solution into the cooking oil reservoirs, along the galley hood plenum, or up into the galley hood exhaust duct. A spring-tensioned cable keeps the system inactive. When this tension is released, the system is activated and N2 is released from a pressurized cartridge. This action opens the lever control heads, releasing the aqueous potassium carbonate.

Figure 37 Aqueous potassium carbonate (APC) fire extinguishing system. Operation Operation of the APC fire-extinguishing system is normally fully automatic.

Manual backup modes of operation are provided at the cylinder assembly, pressure release control box, and the remote manual control box.

Automatic Operation Excessive heat on one of the fusible links melts the link and releases the

cable tension. The extension spring in the pressure-control box pulls the lever, which activates the pressure release cartridge. N2 gas from the pressure-release cartridge activates the lever control head(s), causing the cylinder(s) to discharge.

Manual Operation The aqueous potassium carbonate (APC) system has three manual

modes of operation: 1. At the cylinder assembly, remove the release pin in the lever-control

head completely, and operate the lever. This discharges the cylinder directly. 2. At the pressure release control box, open the box and remove the

release pin completely. This disconnects the release cable and allows the extension spring to activate the system as described under automatic operation.

3. At the remote manual-control box, remove the release pin completely. This disconnects the anchored end of the release cable, releases the tension,

and allows the extension spring to activate the system as described under automatic operation.

Alternatives Many feel that the increased usage of carbon dioxide total flooding

systems, especially in the marine market, is the direct result of our inability to produce a cost effective alternative to halon 1301. From 1987 and nearly up until the halt of production of new halon extinguishing agents in the United States in January 1994, the fire protection industry was generally optimistic that the development of alternatives to halons would produce an improved new line of replacement agents. However, it became apparent that some compromises were necessary in order to accept the alternatives to halons that were ultimately developed. Table 6 is an illustration of some of the agent characteristics the industry felt were important, the level expected and what was actually.

Had all the expectations in Table 6 been achieved, many believe that carbon dioxide total flooding systems would be a thing of the past. Unfortunately, by failing to achieve all the expectations, especially the matter of cost, the employment of carbon dioxide systems has proliferated.

General From a technical standpoint, there are several types of systems that can

perform comparably if not better than carbon dioxide in total flooding applications:

• Halocarbon gaseous extinguishing systems • Inert gas extinguishing systems • Water mist extinguishing systems • In addition, under certain circumstances, there are additional alternative

systems that might be appropriate, including: • Aerosol extinguishing systems • Preaction water sprinkler systems • Ordinary water sprinkler systems • Low, medium and high expansion foam systems • Dry chemical systems

Table 6 Alternatives to Halons - Expectations versus Reality

In the marine market, IMO has developed guidelines for the approval of systems considered equivalent to carbon dioxide systems for the protection of machinery spaces.

Three separate guidelines deal with water mist (“Amendments to the Test Method for Equivalent Water-Based Fire-Extinguishing Systems for Machinery Spaces of Category A and Cargo Pumprooms Contained in MSC Circular 668, Annex, Appendix B,” International Maritime Organization, 4 Albert Embankment, London SE1 7SR, England: June 1996), halocarbon or inert gas (“Amendments to the Test Method for Equivalent Water-Based Fire-Extinguishing Systems for Machinery Spaces of Category A and Cargo Pumprooms Contained in MSC Circular 668, Annex, Appendix B,” International Maritime Organization, 4 Albert Embankment, London SE1 7SR, England: June 1996. "Revised Guidelines for the Approval of Equivalent Fixed Gas Fire-Extinguishing Systems, as Referred to in SOLAS 74, for Machinery Spaces and Cargo Pump Rooms," Annex to IMO Maritime Safety Committee Circular 848, International Maritime Organization, 4 Albert Embankment, London SE1 7SR, England: June 1998.) and aerosol systems (“Guidelines for the Approval of Fixed Aerosol Fire-Extinguishing Systems Equivalent to Fixed Gas Fire-Extinguishing Systems, as Referred to in SOLAS 74, for Machinery Spaces;” MSC/Circ.1007, International Maritime Organization, London: June 2001).

The US EPA funded an earlier report (Wickham, Robert. T, “Status Of Industry Efforts To Replace Halon Fire Extinguishing Agents,” Wickham Associates, Stratham, NH: March 2002 available at http://www.epa.gov/ozone/snap/index.html) addressing the development and market acceptance of several alternatives to halons. The information in that report dealt with the long path to commercialization, the status of various agents along that path, a comparison of environmental properties of the agents and a quick look at some of the relative costs.

From a total flooding system standpoint, that report concluded that there has been commercial acceptance of two types of agents: gaseous agents including halocarbons and inert gas agents and water mist extinguishing systems and that while aerosol extinguishing systems present some potential, those types of agents have not yet achieved any significant level of acceptance, especially in the US.

Gaseous Extinguishing Agents for Fixed Systems From the gaseous extinguishing agents standpoint, the report also pointed

out that some of the agents that had been incorporated into national and international standards ("NFPA 2001 - Standard on Clean Agent Fire Extinguishing Systems - 2000 Edition," National Fire Protection Association, Quincy, MA: February 2000. "International Standard on Gaseous Fire-Extinguishing Systems," ISO 14520-1 through 14520-15, available from Standards Association of Australia, GPO Box 5420, Sydney, NSW 2001, Australia: August 2000.) never really achieved commercial success and others are already on a phase-out schedule (e.g. the HCFC’s). Thus many of those agents are probably beyond consideration as suitable alternatives to halons,

carbon dioxide or anything else. In the end, the agents in Table 6.6 can be considered viable gaseous alternatives to compete with carbon dioxide in many applications. While accepted for the next editions but not yet included in the current cited standards, a new halocarbon agent, identified as FK-5-1-12, or 3M Novec 1230 Fire Protection Fluid, has been listed as acceptable by EPA’s SNAP program, “Protection of Stratospheric Ozone: Notice 17 for Significant New Alternatives Policy Program,” 40 CFR Part 82, Environmental Protection Agency, [FRL–7425–6], Federal Register / Vol. 67, No. 245 / 77927, Friday, December 20, 2002. so it too is included in Table 7.

Table 7 Gaseous Alternatives to Carbon Dioxide for Total Flooding Systems

Water Mist Systems To many, water is perceived as a tremendous fire extinguishing agent. It is

readily available, inexpensive and environmentally non-problematical. Further, the concept of using it in a mist form makes water even more attractive as a fire extinguishing agent since:

• the high effective surface area of the water mist “particles” makes it more capable (than a heavy stream of water) in its process of cooling the fuel and the surroundings and in readily evaporating (turning into steam) and diluting the oxygen, thus inhibiting the fuel burning rate, and

• that increased effectiveness then translates into requiring very small quantities of water to achieve extinguishment (when compared to more conventional water application methods), thus minimizing the collateral damage often associated with higher flow rate water systems. Water mist has made in-roads into 3 major market applications, two of

which have heretofore been served by carbon dioxide systems: the protection of turbine and diesel powered machinery, the protection of machinery spaces aboard ships and as an alternative to water sprinkler systems aboard passenger ships. There are accepted test protocols [Factory Mutual Research (“Approval

Fire Test Protocol for Water Mist Systems for the Protection of Combustion Turbine Enclosures With Volumes Up To, And Including, 2825 ft3 (80 m3 ),” Factory Mutual Research, Norwood, MA: 1985.) for the turbines and IMO (“Amendments to the Test Method for Equivalent Water-Based Fire-Extinguishing Systems for Machinery Spaces of Category A and Cargo Pumprooms Contained in MSC/Circ.668, Annex, Appendix B,” MSC Circular 728, International Maritime Organization, London: June 1996, “Guidelines for the Approval of Fixed Water-Based Local Application Fire-Fighting Systems for Use in Category A Machinery Spaces,” MSC Circular 913, International Maritime Organization, London: May 1999, “Revised Guidelines for Approval of Sprinkler Systems Equivalent to That Referred to in SOLAS Regulations II-2/12 Including Appendix 1 Component Manufacturing Standards For Water Mist Nozzles and Appendix 2 Fire Test Procedures for Equivalent Sprinkler Systems in Accommodation, Public Space and Service Areas on Passenger Ships,” IMO Res.A.800 (19), International Maritime Organization, London.) for shipboard] for these market applications and those who have their systems successfully tested have achieved the right to participate.

While water mist shows a lot of promise, it is having a difficult time capitalizing on its utility in the marine market. There it has become apparent that water mist tends to work well as a total flooding agent in extinguishing large fires but has difficulties extinguishing small fires in large spaces, a requirement that is built into the IMO test protocol. At this time, those manufacturers who have successfully tested their water mist systems to the IMO test protocol have done so by employing very expensive techniques or additional agents and hardware that are considered by many to be unnecessary for the types of fires for which a fixed system is intended. The additional costs embodied in the water mist systems by this total extinguishment of the small fire requirement is what makes the difference between water mist systems being very competitive and being the most costly, as will be shown later in the report.

IMO has a working group studying this situation and that group is considering proposals that suggest an overhaul to the test methods and approval guidelines. Should IMO change its water mist requirements to something more flexible regarding the small fires in large spaces, it will make a significant difference in the cost and thus market acceptance of water mist systems going forward.

Other Types of Agents for Fixed Systems In addition to the gaseous agents listed in Table 20 and the water mist

systems, there are several other types of agents being promoted as halon replacements in fixed systems, including inert gas generators and aerosols. These systems, when developed further, may become viable alternatives for applications now largely served by carbon dioxide total flooding systems.

3.7.6 Inert Gas Generators Inert gas generators utilize a solid material, which oxidizes rapidly,

producing large quantities of CO2 and/or nitrogen. The use of this technology to date has been limited to specialized applications such as dry bays on military aircraft. This technology has demonstrated excellent performance in these applications with space and weight requirements equivalent to those of halon 1301. There is work underway to adapt this technology to industrial and marine applications.

Aerosols Another technology being developed is the use of aerosols as

extinguishing agents. These take advantage of the well established fire suppression capability of

solid particulates - as demonstrated with dry chemicals - with the possibility of significantly reducing the amount of residue associated with the current dry chemical agents. The NFPA has formed a technical committee on “Aerosol Extinguishing Technology” (The technical committee member list is available at http://www.nfpa.org/PDF/ComList.pdf?src=nfpa), which will develop a standard to provide the guidance for appropriate application of these systems. As illustrated in Table 8 several other standards making organizations are in the process of developing or have completed their guidelines for the use of these types of agents.

Table 8: Organizations Developing Guidelines for Aerosol Systems

http://www.nfpa.org/PDF/ComList.pdf?src=nfpa

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