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TS 10 –1. VENTILATION. The systematic removal of heated air, smoke, and gases from a structure and replacement with cooler, cleaner air. TS 10 –2. TYPES OF VENTILATION. Vertical Trench (strip) Basement Horizontal Natural Forced Mechanical positive-pressure - PowerPoint PPT Presentation
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VENTILATION
The systematic removal of heated air, smoke, and gases from a structure and replacement
with cooler, cleaner air
TS 10–1
TYPES OF VENTILATION
• Vertical – Trench (strip)– Basement
• Horizontal – Natural– Forced
• Mechanical positive-pressure• Mechanical negative-pressure• Hydraulic
TS 10–2
WHY VENTILATE?
• Aids in saving lives
• Aids in suppressing fire
• Aids in reducing property damage
TS 10–3
TODAY’S INCREASING NEED FOR VENTILATION
• Increased fuel load in all occupancies due to increased use of plastics and other synthetic materials
• More products of combustion
• More dangerous products of combustion
• “Tighter” homes making heat retention greater– Increased insulation– Energy-saving glass– Vapor barriers
TS 10–4
ADVANTAGES OF VENTILATION TO RESCUE OPERATIONS
• Improves visibility
• Allows for faster location of unconscious victims
• Simplifies and expedites rescue
• Makes conditions safer for firefighter and victims
TS 10–5
ADVANTAGES OF VENTILATION TO FIRE ATTACK & EXTINGUISHMENT
• Removes smoke, gases, and heat from building
• Facilitates entry of firefighters
• Reduces obstacles that hinder firefighters
• Increases visibility for quicker location of seat of fire
TS 10–6
ADVANTAGES OF VENTILATION TO FIRE CONTROL
• Reduces mushrooming
• Reduces flashover potential
• Reduces backdraft potential
• Controls fire spread
TS 10–7
ADVANTAGES OF VENTILATION TO PROPERTY CONSERVATION
• Permits rapid extinguishment
• Reduces water, heat, and smoke damage
• Confines fire to an area
• Allows salvage operations and fire control to take place concurrently
TS 10–8
BACKDRAFT INDICATIONSVS 10-2
PuffingSmoke
Black SmokeBecoming Dense
Yellow-Gray
Walls TooHot to Touch
Dull Orange Glowof Visible Fire
PressurizedSmoke Coming
From SmallCracks
Darkened Windows
Rattling Windows
Hot UnbrokenGlass
BACKDRAFT PREVENTION
Top (vertical) ventilation is the primary method
of preventing backdraft.
TS 10–9
LIFE SAFETY HAZARDS IN UNVENTILATED BUILDINGS• Obscurity caused by dense smoke
• Presence of toxic gases
• Lack of oxygen
• Presence of flammable gases
• Danger of backdraft
• Danger of flashover and rollover
TS 10–11
FACTORS DETERMINING HORIZONTAL OR VERTICAL
VENTILATION • Building type and design
• Number and size of wall openings
• Number of stories
• Number of staircases, shafts, dumbwaiters, ducts, roof openings
• Availability of exterior fire escapes
• Exposure involvement
TS 10–12
VENTILATION PROBLEMS: BASEMENTS
VS 10-4
• Need to Descendthrough Heat andSmoke
• Blocked or Secured Outside Entrances
• Difficulty of UsingNatural Ventilation
VENTILATION PROBLEMS: WINDOWLESS BUILDINGS
VS 10-5
• Late Detection DelayingVentilation and Creating Backdraft Conditions
• Horizontal VentilationDifficult or Impractical
• Usually Require Mechanical Ventilation
VERTICAL FIRE EXTENSION
Opening for ventilation purposes before the fire is located may spread the fire to areas
that otherwise would not have been affected.
TS 10–13
VENTILATION OPENING LOCATION & SIZE FACTORS
• Availability of natural openings
• Fire location
• Building construction
• Wind direction
• Fire phase
• Building condition
• Building contents
TS 10–15
• Roof type and condition
• Effects on fire
• Effects on exposures
• Attack crew’s readiness
• Ability to protect exposures
• Size
VERTICAL VENTILATIONVS 10-6
Roof Opening(At least 4’ x 4’[1.2 m x 1.2 m])
VERTICAL VENTILATION
Opening the roof or existing roof openings to allow heated gases and smoke to escape
to the atmosphere
TS 10–16
PRE-VENTILATION SAFETY PRECAUTIONS
• Consider type of building involved.
• Consider location, duration, and extent of fire.
• Observe safety precautions.
• Identify escape routes.
• Select place to ventilate.
• Move personnel and tools safely to roof.
TS 10–17
ROOF TYPESVS 10-7
FlatMansard
Shed
ButterflyHip
Gable
Lantern GambrelArch
BASEMENT FIRES
• First extension commonly into the attic
• May be ventilated in a variety of ways:– Horizontal ventilation through ground-level
or below-ground windows – Through interior vertical shafts (stairwells,
hoistway shafts, etc.)– Mechanical ventilation through a hole in the
floor near a ground-level door or window
TS 10–29
ELEVATED STREAMS
• Can force air and gases back into building if not used properly
• If projected just above the horizontal plane, are effective in subduing sparks and flying brands rising from ventilation opening and in reducing heat of thermal column
• Should never be projected through the ventilation hole while firefighters are still inside building
TS 10–30
VENTILATIONVS 10-13
Correct Application
Incorrect Application
FACTORS THAT CAN DESTROY VERTICAL VENTILATION
EFFECTIVENESS• Improper use of
forced ventilation
• Excess glass breakage
• Fire streams directed into ventilation holes
• Skylight breakage
TS 10–31
• Explosions
• Burn-through of the roof, floor, or wall
• Additional openings between attack team and upper opening
HORIZONTAL VENTILATIONVS 10-14
Windward
Wind Direction
Leeward
Fresh Air
HORIZONTAL VENTILATION
Venting of heat, smoke, and gases through wall openings such as windows and doors
TS 10–32
HOW HORIZONTAL FIRE EXTENSION OCCURS
• Through wall openings by direct flame contact or by convected air
• Through corridors, halls, or passageways by convected air currents, radiation, and flame contact
• Through open space by radiated heat or convected air currents
TS 10–34
• In all directions by explosion or flash burning of fire gases, flammable vapors, or dust
• Through walls and interior partitions by direct flame contact
• Through walls by heat conduction through beams, pipes, or other objects that extend through walls
HORIZONTAL EXTENSION KEY POINTS
• Wind is helpful but too much wind can be detrimental.– Windward — Side of building the wind is striking– Leeward — Opposite side of building
• Horizontal ventilation may block escape of occupants.
• There is an ignition hazard to higher portions of the fire building posed by rising heated gases.
TS 10–35a
HORIZONTAL EXTENSION KEY POINTS (cont.)
• Do not open building until charged lines are in place at attack entrance point, where fire might be expected to spread, and in positions to protect exposures.
• Take precautions against upsetting horizontal ventilation.– First open a door on leeward side to create a normal
process of thermal layering.– Know that opening doors between fire fighting crews
and exit point reduces intake of fresh air.
TS 10–35b
UPSETTING HORIZONTAL VENTILATION
VS 10-15
FORCED VENTILATION
Ventilation accomplished mechanically (with fans) or hydraulically
(with fog streams)
TS 10–36
PORTABLE FAN SAFETY MEASURES
• Shut down before moving.
• Carry by handles.
• Clear personnel from area before starting.
• Do not place where clothing, draperies, or curtains can be drawn into fan.
• Avoid the discharge stream: heat and particles may be projected by venting equipment.
TS 10–37
ADVANTAGES OF FORCED VENTILATION
• Ensures more positive control of fire
• Supplements natural ventilation
• Speeds removal of contaminants
• Reduces smoke damage
• Promotes good public relations
TS 10–38
DISADVANTAGES OF FORCED VENTILATION
• May cause fire to intensify and spread
• Depends upon a power source
• Requires special equipment
TS 10–39
TYPES OF FORCED VENTILATION
VS 10-16
Positive Pressure Horizontal Mechanical Hydraulic
FORCED VENTILATION MECHANICAL NEGATIVE PRESSURE
VS 10-17
Wind DirectionIntake
Opening(Optional
In-BlowingEjector)
Draft Path
Pressure Inside BuildingLower Than Outside Building
Smoke Ejector
(Exhaust)
Salvage CoverOr Tarp
BlockingOpening
Around Ejector
Closed Doors
FORCED VENTILATION MECHANICAL POSITIVE PRESSURE
VS 10-18
ClosedDoors
High Power
Fan
ExitOpening
(Same Size AsEntry Opening)
Draft Path
Pressure Inside BuildingHigher Than
Outside Building
Cone CoveringEntire Door
Opening
ADVANTAGES OF MECHANICAL POSITIVE-PRESSURE
VENTILATION• No need to enter smoke-filled environment
• Effectively supplements both horizontal and vertical ventilation
• Allows for efficient removal of smoke and heat
• Does not effect building contents or smoldering debris
• Is faster than negative-pressure ventilation
TS 10–40a
ADVANTAGES OF MECHANICAL POSITIVE-PRESSURE VENTILATION (cont.)
• Does not interfere with ingress or egress
• Is easier to clean and maintain positive-pressure than negative-pressure fans
• Is applicable for all types of structures
• Allows for directing heat and smoke away from unburned areas or paths of exit
TS 10–40b
DISADVANTAGES OF MECHANICAL POSITIVE-PRESSURE VENTILATION
• Requires an intact structure
• May increase interior levels of carbon monoxide
• May extend hidden fires
TS 10–41
GUIDELINES FOR EFFECTIVE POSITIVE-PRESSURE VENTILATION
• Take advantage of existing wind conditions.
• Make certain that cone of air from fan covers the entire entry opening.
• Systematically open and close doors or increase the number of fans to reduce size of area being pressurized.
• Keep size of exit opening in proportion to the entry opening.
TS 10–42
FORCED VENTILATION HYDRAULIC
VS 10-19
Fog Stream(Covering 85% 90% of Opening
Nozzle Tip(At least 2 ft. [0.6m]Back from Opening)
HYDRAULIC VENTILATION• Typically used to clear a structure of heat, smoke,
steam, and gases following the initial knockdown of fire
• Takes advantage of air that is drawn into the fog stream to help push the products of combustion out of structure
• Fog pattern should be wide enough to cover 85 to 90 percent of the window or door opening through which the smoke will be pushed
• Nozzle tip should be no closer than 2 feet (0.6 m) from ventilation opening
TS 10–43
DISADVANTAGES OF HYDRAULIC VENTILATION
• May increase amount of water damage
• Will put a drain on available water supply
• In freezing temperatures, will increase ice in area surrounding building
• Requires nozzle firefighters to remain in heated, contaminated atmosphere throughout operation
• Operation may be interrupted if nozzle team has to leave the area
TS 10–44