Flammable Atmospheres

8/14/2019 Flammable Atmospheres

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PREVENTION

Understanding

ItsCauses


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THE FIRE TRIANGLEFor a fire to start three conditions mustbe met at the same time:

FUEL

OXIDIZER IGNITION


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THE FIRE TRIANGLEFuels are materials that burnThe higher the temperature, the easier andquicker they burnCommon fuels include:-- Solvents such as acetone, alcohols, and

toluene-- Gases such as acetylene and propane-- Solids such as wood and paper


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THE FIRE TRIANGLEOxidizers: Oxygen or other substancescapable of releasing oxygen to a fireCommon oxidizers include:

acids, especially nitric and perchloric acidschlorine dioxideOthers such as potassium permanganateand potassium chlorate


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THE FIRE TRIANGLEFire prevention consists of making surethat the three legs of the fire triangle

never meet FUEL

OXIDIZER IGNITION


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FIRE PROPAGATIONRecent studies indicate that the spreador propagation of a fire is alsodependent on a fourth factor - thechemical chain reactions that can occuras a result of heat produced by the fire.


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FLAMABLE CONDITIONS A fire will not always start when thelegs of the fire triangle meet, unless allthree elements are present in therequired amountsFor example, vapors from a flammableliquid must be mixed with a certainamount of air in order to ignite andpropagate a flame


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FLAMMABLE RANGELower Flammable Limit: The lowestconcentration at which a fuel/air mixturewill burn. Below this there is too little fuel(the mixture is too lean)Upper Flammable Limit: The highest

concentration at which a fuel/air mixturewill burn. Above this there is not enoughoxygen (the mixture is too rich)


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FLASH POINTThe lowest temperature at whichsufficient vapors form above the liquidto produce an ignitable mixture with air


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FLAMMABILITY RANGEThe Department of Transportationclassifies liquids for transportationregulation purposes

Flammables: All liquids with a flash pointbelow 100 degrees Fahrenheit

Combustibles: All liquids with a flashpoint above 100 degrees Fahrenheit


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Flammable AtmospheresCritical Factors:

Oxygen content in the air.

Flammable gases or vaporsFlammable dust (visibility of 5 or less) Proper air/gas mixture can lead toexplosion

Typical Ignition Sources:Sparking or electric tool.Welding / cutting operations.Smoking


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Lower Explosive Limit vs. Upper

Explosive LimitAIR

COMBUSTIBLE

LEL UEL

TOO LEAN TO BURN TOO RICH TO BURNEXPLOSIVE RANGE

Gasoline

100% LEL0%

100%1.4% Flammable range 7.6% by volume0%


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Explosive LimitAIR

COMBUSTIBLE

LEL UEL


Gasoline

100% LEL0%



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Explosive LimitAIR

COMBUSTIBLE

LEL UEL


Gasoline

100% LEL0%



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Explosive LimitAIR

COMBUSTIBLE

LEL UEL


Gasoline

100% LEL0%



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Explosive LimitAIR

COMBUSTIBLE

LEL UEL


Gasoline

100% LEL0%



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FLAMMABLE GASES & SOLIDSGas cylinders such as acetylene weldinggas need to be properly stored and used

Solids such as paper, wood, and clothneed to be treated as potential fuelsRags or paper soaked with flammableliquids need to properly handled anddisposedMetals that burn (pyrophorics) areespecially dangerous


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STORAGE & HANDLINGSince it is impossible to eliminateoxygen from the fire triangle, fire

prevention depends on trying to:Eliminate sources of ignitionRestrict the amount of flammable and

combustible liquids


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Eliminate sources of ignitionChoose the least hazardous materialspossibleReduce the amounts stored to aminimum

Use safe storage procedures andcontainersEnsure containers are properly labeled

STORAGE & HANDLING


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CONTAINER LABELINGFlammable liquids should have a labelsuch as this:

DANGER FLAMMABLE

KEEP AWAY FROM HEAT, SPARKS &OPEN FLAMES

KEEP CLOSED WHEN NOT IN USE


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NFPA LABELING SYSTEM


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MATERIAL SAFETY DATA

SHEETS (MSDS)Information regarding fire preventionand fire extinguishing

Safe storage and handling proceduresSpill clean-up proceduresProper labeling

Use to compare products for hazardssuch as flash point and flammabilityrange


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STORAGE AMOUNTSLocal and state fire codes limit theamounts of flammable and combustibleliquids that can be stored in variouslocations

CHECK WITH YOUR LOCAL FIREDEPARTMENT


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STORAGE AREASBest location to store large amounts offlammable and combustible liquids is aseparate outside buildingIf this is not possible, then a suitableflammable storage cabinet or inside

storage room should be built


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FLAMMABLE STOREAGE

CABINETSBuilt to meet OSHA and NFPA standardsLabeled in large letters:

FLAMMABLE-- KEEP FIRE AWAYMaximum of 120 gallons of Class I, II,and III A liquids (60 gallons of Classes I

and II)Maximum of three cabinets may belocated in a given fire area


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STORAGE CONTAINERSQuantities of flammable liquidsexceeding one pint should be stored inapproved portable safety cansIn instructional laboratories the largestcontainer size for flammable liquids is

one gallon (or a two gallon safety can)


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STORAGE DRUMS55 gallon drums should only be storedin a separate storage area away fromheat and sunlight.The maximum size of drum that shouldbe stored indoors is 5 gallons


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INSIDE STORAGE ROOMSRequirements found in NFPA 30(Flammable & Combustible Liquids Code)

Fire resistance rating of 2 hours for walls,floor, and ceilingClass B fire doors

Automatic fire protection systemsMechanical ventilation depending on theamount storedClass I-Division 2 electrical wiring andfixtures


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DISPENSINGWhen dispensing from drums, useapproved transfer pumps or drumfaucetsWhen pouring flammable liquids from adrum to a metal container, ground the

drum and bond the metal container tothe drum to prevent the build-up of anystatic charge


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SPILLS AND LEAKSSpills must be quickly and safely cleaned upto prevent flammable vapors from igniting

A sufficient quantity of absorbent material shouldbe kept on handTreat spill clean-up materials as flammable anddispose of separately from the regular trash

Large spills of flammable liquids (more than onequart) need special cleanup procedures


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FIRE FIGHTINGFour Basic Types of Fires

Class A -- Common SolidsClass B -- Flammable LiquidsClass C -- Electrical Equipment

Class D -- Burning Metals


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FIRE EXTINGUISHERSClass A Types -- Water based for areascontaining ordinary combustibles

Class ABC Multipurpose Dry Chemical --Displaces oxygen and smothers the flame Class ABC Halon 1211 -- Inhibits chain

reactions of a fireClass BC -- Carbon Dioxide displaces airand cuts off the oxygen supply


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Automatic Sprinkler SystemsWater -- Sprays a mist when activatedby the heat of a fireHalon -- Sprays a halogenated chemicalonto the fire. Halons decompose totoxic gases when heated. Use must be

carefully planned.


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OSHA REQUIRED PROCEDURES

FOR FIGHTING FIRESOSHA regulations allow for threesituations:

Total evacuation in case of fire alarm

Partial evacuation with some employeesallowed to use fire extinguishers All employees allowed to use fireextinguishers

OSHA specifies training requirements ifany employees are allowed to use fireextinguishers


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USING FIRE EXTINGUISHERSIf you think you can handle the fire, soundthe fire alarm to set the emergency plan inoperationGrab the closet fire extinguisher thatconforms to the type of fire

Activate the fire extinguisher and follow thedirections for use

If at any time you feel overwhelmed, or theextinguisher charge runs out, leave the areaand wait for the professional fire fighters


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INTEGRITY OF EQUIPMENTFire fighting equipment must be wellmaintained and checked periodically for

pressure and integrityFire extinguishers must be placed prominentlyaccording to OSHA regulationsFire suppression equipment, such as sprinklersystems, must also meet the appropriateOSHA and NFPA standards


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REMEMBER !Fire Prevention Is

Everyones Responsibility

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Flammable Atmospheres

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