Fire Service Ventilation (7th Edition)
Chapter 2-Ventilation Size Up
Test Review
- Ventilation size-up includes determining location/extent of fire, assessing life hazards, and identifying building construction features.
- Infrared detection equipment can detect hot spot without entering structure and detect people when used inside a structure.
- Hydrocarbons are products containing hydrogen and carbon.
- Ventilating as close to the seat of the fire as possible is considered offensive ventilation.
- Cutting a trench/strip ventilation ahead of a fires path is considered defensive ventilation.
- When assessing life hazards, get data on number and location of occupants, obtain the structure's use/processes, and identify hazardous materials present.
- Fire crews must coordinate with ventilation groups since ventilation often increases the intensity of fire.
- Directing a fire stream into a vent opening does not permit smoke and heat to exit and can cause steam burns to crews inside.
- Severity of fire can be determined by the type of fuel burning, fire protection devices present, degree of confinement, and the time elapsed since the fire began.
- Creating ventilation openings other than over the seat of the fire can spread fire to uninvolved portions.
- Fire involving ordinary combustibles will initially produce an off-gray white or blue-white smoke of little density.
- Dense black smoke indicates burning hydrocarbons (rubber, tar, oil, some plastics).
- Brown or copper color smoke indicates nitrogen oxide presence.
- Gray-yellow smoke exiting under pressure through small cracks indicates possible backdraft conditions.
- Fire intensity/location can be determined by feeling structural components for heat.
- Discolored/blistering paint indicate high heat.
- Hot spots on floors above the fire floor can indicate fire location.
- Attic fires may be revealed by areas of melted snow on roofs.
- Readiness of rescue, fire attack, and exposure protection crews determines when to ventilate.
- Fire location, occupant location, interior/exterior exposures, construction type, occupancy purpose, fire progression, building condition, existing openings, wind direction, and availability of personnel/equipment determine where to ventilate.
- Horizontal ventilation might be useful with small fires, wall openings are close to seat of fire, fire involves top floor, or when fire has not entered structural voids.
- Vertical ventilation might be useful when fire is in attic or on top floor, in windowless buildings, in buildings with large vertical shafts, or when fire has entered structural voids.
- Natural ventilation is fast and efficient, however, may need to be supplemented with forced ventilation for facilitate rescue/fire attack.
- Forced ventilation is appropriate when location/extent of fire has been determined, natural ventilation will not be sufficient, when fire is below grade, or when non-fire contaminated atmospheres are present.
- Horizontal ventilation may threaten internal exposures due to the path of smoke and fire gases being the same as those used by occupant to escape or due to smoke reentering structure through air drawn in by HVAC units.
- Horizontal ventilation may threaten external exposures by lapping up to upper parts of the structure or by igniting exposure buildings through radiant heat.
- External exposure threats due to vertical ventilation include hot embers carried by convection to the roofs of nearby structures or to dry vegetation or igniting structures taller than the fire structure through radiant heat.
- The side of a building that the wind strikes is the windward side.
- The side of a building that the wind blows away from is the leeward side.
- Wind can affect ventilation by blowing fire toward external exposures, feeding oxygen to the fire, or by blowing fire into uninvolved portions of the structure.
- High humidity can keep products of combustion from rising into the atmosphere.
- Snow and ice can increase loads on roofs, conceal roof features, and delay operations.