Ventilation

Given information on ventilation the firefighter will be able to identify when and where to safely apply ventilation so that heat, smoke, and gases can be removed from a structure to improve conditions for fireground operations. This will be done to a written test accuracy of 75% and complete the practical evolutions in the allotted time to the instructor’s satisfaction.

Goal

VentilationObjectives The student will:• Understand the importance of

ventilation.• Be able to identify when and where to

ventilate. • Understand the dangers of ventilation.• Be able to identify the different types of

roof construction.

Ventilation

Objectives Con’t

• Know the the different tools used for ventilation.

• Understand the compilations of ventilation

• Have an understanding of positive and negative pressure ventilation.

• Know how to explain and perform vertical ventilation.

Ventilation

Objectives Con’t

• Know how to explain and perform natural ventilation.

• Know how to explain and perform horizontal ventilation.

Ventilation

Overview

• Importance of ventilation• Different techniques • Advantages and disadvantages• Precautions and dangers • Roof Types, and their construction• Different types of ventilation• Tools needed for ventilation

Ventilation

• The systematic removal and replacement of heated air, smoke, and gases from a structure with cooler air

Ventilation

Ventilation

Advantages• Rescue• Increases survivability of trapped victims• Improves visibility, and reduces heat levels• Reduction of flashover and backdraft

potential• Fire attack• Fire spread control• Property Conservation

VentilationDisadvantages or Improper Ventilation• Fire spread• Accelerated burning• Puts firefighters in danger• Triggers Backdraft• Structural Integrity

VentilationDangers of ventilations• Light weight construction.• Can cause fire to intensify and spread.• Places firefighters in danger.• Backdrafts.• Weather conditions.

Ventilation

Complications

• Lack of Pre-planning• Barred/Screen windows.• Overhead obstructions.• Access• Weather• Improper equipment• Man power

VentilationComplications (Con’t)• Visibility• Roof pitch/type

Whe

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here

How

?

VentilationVentilation Size-up • Is there a need. (Why)

• Where is it needed. (Where)

• Type needed. (How)

• Structural conditions allow for safe operations.

Timing (When)

VentilationCoordinated Fire Attack

• Vent as close to the point of origin as possible coordinating with interior attack crew.• Hose line ready and charged while

firefighters are advancing.

• Ventilation of the fire room with outside vent person.

Primary Consideration

RESCUE OR SUPPRESSION

PRIORITY WITH INTERIOR ATTACK

To keep smoke, heat, and gases away from

victim.

To reduce heat and Increase visibility

For firefighters

VentilationTypes of Ventilation• Natural• Horizontal• Vertical• Mechanical

Ventilation

Natural Ventilation – The means of ventilating a structure without the assistance of powered equipment.

VentilationNatural Ventilation• Wind.• Currents created by the fire.

Use Caution!!!

Ventilation

Horizontal Ventilation – Is the venting of heat, smoke and gases through wall openings such as windows and doors.

Ventilation

VentilationHorizontal VentilationUses:• Residential• Multistoried structures• Large unsupported open spaces.

VentilationVertical Ventilation Opening the roof or using existing roof

opening to allow heated gases and smoke to escape.

Ventilation

Natural Opening

• Sky lights• Scuttle Hatches• Windows• Doors• Shafts• Ventilators• Stairways

Ventilation

Roof openings• Cut large opening

– Minimum 4’x4’– Windward side

• Smaller openings– May be necessary do to conditions

• Trench cut– From Exterior wall to exterior wall– 4’ wide

VentilationVertical Ventilation• Uses:• Attics• Areas open to the roof

Ventilation

Ventilation

Mechanical Ventilation (Forced) – The means of ventilating a structure with the assistance of powered equipment.

Positive-pressure ventilation (PPV), and Negative-pressure ventilation (NPV)

Ventilation

VentilationPositive-pressure ventilation (PPV)• Induces fresh air into a confined area or

structure resulting in an increase of pressure in that area which forces contaminated air through pre-selected and/or controlled openings

• Must coordinate with operation, and attack crews

Ventilation

PPV Advantages

• Two times more effective than NPV• Does not block doorways• Does not expose personnel to

contaminants while positioning blower • Provides fresh air, reduces heat, and

CARBON MONOXIDE during overhaul operations

Ventilation

Disadvantages

• Noisy• Not effective if there are to many

openings• Can cause fire spread, or ignite

smoldering embers• Raise CO levels with gas fans.

VentilationPPV Fan Placement

• A single fan should be placed so the cone of pressurized air JUST covers the opening

• Tilting the fan back about 20-30-degrees will enhance the operation

• Square box type fans can be stacked to achieve the same effect.( one fan on top of the other)

Ventilation

Back far enough to seal the opening

PATH

EXHAUST

Single unit operation

Exhaust opening should b ¾’s to twice the size of entrance

Ventilation

YES!

If you don’t have standard PPV blowers on your apparatus, simply use NPV devices

and stack them on top of each other, then reverse their positioning placing exhaust side in.

- SMOKE EJECTORS -

VentilationPPV Fan Placement• Two fans one in front of the other (series,

tandem, or in line)• Front fan (Largest) about 2 feet from opening,

and the back fan will be set back far enough to cover the opening with pressurized air

• Two or more fans side by side(parallel or dual)• Fans should sit side by side and back far

enough to cover the opening with pressurized air

Ventilation

DISTANCE

EXHAUST

2-3 feet Larger

Fan

Positive Pressure

Series, tandem, or in-line

Back far enough to seal the opening

VentilationParallel or dual

Ventilation

Exhaust opening

• Most effective when the exhaust opening is three quarters to two times the size of the entrance opening.

• Varies do to size of the fan or the amount of fans operating.

• Optimum efficiency is easily obtained by a combination of training and practical experience.

VentilationDetermine PPV fan Size for a Given Structure• Apply the PPV Rule of Thumb

- Single family dwelling with up to 2,000 square feet: 18- to 21-inch fans

- Ranchers and multistory dwellings up to 4,000 square feet: 24-inch fan

- Larger structures (greater than 4,000 square feet) require multiple fan application with 2 to 3 24-inch fans

- Always use multiple fans on high-rise structures 10 floors or greater

VentilationNegative-pressure ventilation• Draws contaminates from interior to the

exterior causing a negative-pressure in the contaminated area allowing fresh air to enter from an outside source through another opening.

Ventilation

Advantages

• Usually operates off of a 110 volt• Usually explosion-proof motor

Ventilation

Disadvantages• Exposes personnel to the contaminated area• Placement in doorways and windows require

hangers, straps or other accessories to position them effectively

• Block entrances and hallways • Contaminates are drawn through the fan

causing additional cleanup and maintenance

VentilationMechanical Devices• Gas Fan• Electric Fan• Mobile units• HVAC systems• Exhaust Systems• Hose steams (Hydraulic)

Ventilation

Gas Fans

• 2-cycle and 4-cycle engines• 18 to 24 inch in diameter• 3200 to 15,000 CFM• Many different manufactures and styles• Maintenance ( Gas, oil, and air filters )• Can cause CO levels to rise in structure

Ventilation

Electric Fans

• Both PPV and NPV• Require electric cords• NPV fans sizes 16 to 24 inch, from 2 to 3

hp• Square or circular encased, including

motor• PPV fans are 18 to 24 inch, from 3200 to

30,000 CFM

VentilationMobile ventilation units • Diesel• PTO• Hydraulic• 30,000 to 211,000 CFM

Ventilation

HVAC Systems

• Some are designed to reverse to draw out contaminated air from buildings

• Maintenance personnel from building will provide that information

• If unsure Turn units off. • Preplanning

Ventilation

Exhaust Systems

• Some buildings have systems in place for other uses.

• Maintenance personnel from building will provide that information

• Preplanning

VentilationHose Stream (Hydraulic)

VentilationCare and Maintenance

• PPV Blowers or Fans- Use proper oil and fuel mixtures

- Keep belts tight and snug

- Keep shroud(s) intact

- Check fluid levels. Change fuel regularly and replace with fresh

- Run blower

- Keep rubber feet or base intact

• NPV Blowers or Fans

- Clean blades and motor regularly

- Keep electric cords and switches intact

- Keep shroud(s) intact

- Listen for any unusual noises during operation

Ventilation• No properly trained crew

• When interior search or rescue teams or occupants are between the fire and exit point of smoke

• For well-involved attic fires with no egress venting

• When fire is present in the walls of balloon construction and no egress point is identified

• When backdraft conditions are evident.

• When the origin of fire is unknown.

• Too many openings in a structure preventing air flow from effectively pressurizing interior

Contra indicators for PPV

VentilationVentilating multiple floors• Pressurize stair shaft common to all

floors• Start with lower levels and work up• Vent horizontally through exterior

openings• Vent to opposite stair shaft

Ventilation

VentilationRoof Construction• Lightweight wood or metal joist• Heavy steel trusses• Wood “I” beams• Built-up roof• Concrete Roofs• Metal roofs

VentilationLightweight wood or metal trusses• Trusses in place of rafters• Wood or metal decking• Built-up roof• Allows horizontal fire spread • Fails after 5-10 minutes of fire exposure

VentilationHeavy steel trusses• Metal decking with built-up roof• Starts to fail at 1000 degrees

Ventilation

Wood “I” beams

• Substitute for lightweight trusses• Contributes fuel to the fire• Fails within 5 to 10 minutes of fire

exposure

Ventilation

Concrete roofs

• Precast concrete• Lightweight concrete• Reinforced concrete• To vent this type is difficult and time consuming• Use natural openings, skylights, scuttles,

ventilators, stairwells

Ventilation

Metal roofs

• Light-gauge steel• Corrugated galvanized sheet metal• Aluminum• Vent with power saws using metal cutting

blades, axe, or sheet metal cutters.• Use natural openings

Ventilation

Flat Roof

• Industrial, commercial, and apartment buildings

• Frequently pierced by chimneys, vent pipes, shafts, scuttles, and skylights

• May be surrounded and or divided by parapets

• May have HVAC unit on them

VentilationFlat roof construction• Wooden, metal, or concrete joist• Wooden or metal decking• Waterproof materials, insulation, gravel• Reinforced, lightweight concrete, or

precast concrete

VentilationBuilt-up roof construction

OR PLYWOOD

GRAVEL

Ventilation

Built-up Roof• Opening built-up roof

– Remove gravel if present– Make inspection cut– Cut insulation and composition down to decking– Remove materials, sound roof for rafters or bar

joist, then cut decking and remove.– Be careful not to cut to deep to avoid causing

structural damage to the rafters

Ventilation

VentilationOpening a flat roof • Determining the location of the opening

– Location and extent of fire – Wind direction– Exposures– Obstructions

• Open using the built-up roof method.

Ventilation

Pitched Roofs

• Rafters or trusses• 1X boards or plywood sheeting• Felt paper• Shingles- wood, asbestos, composition,

metal, slate or terracotta tile.• May be gypsum slabs, approximately 2”

thick, laid between metal trusses.

Ventilation

VentilationOpening a pitched roof• Determine the location of the opening

same as flat roof• Place roof ladder on the windward side

of opening• Locate the rafters• Cut opening working the farthest

distance from you towards yourself• Remove the decking• Push a tool into the hole to open a

possible ceiling below

Ventilation

Arched Roofs

• Bowstring truss• Trussless arched roof• Lamella roof

Ventilation

VentilationOpening an arched roof

• Cutting is the same as a pitched roof• Use of a roof ladder would be unlikely• Because of the potential for sudden collapse

under fire conditions, roof operation should be done from an aerial ladder or tower.

Ventilation

Hand tools• Axe• Halligan bar• Pike poles• Sledge hammer• Can opener• Hand saws• Ladders

Ventilation

Power tools

• Vent saws• Chain saws• Circle saws• Reciprocating saws

Ventilation

Power tool safety• Proper maintenance• Know tool operations and capabilities• PPE• Start tool before taking to operational area• Never carry, hoist, or climb while running• Keep front arm stiff while operating tools• Work with a partner

Ventilation

Review• Discussed the importance of ventilation• Discussed ventilation techniques• Discussed the advantages and disadvantages

of ventilation• Discussed precautions and dangers of

ventilation• Discussed the different types of roofs, and their

construction• Discussed different types of ventilation• Discussed the tools needed for ventilation