Chapter 14 Ventilation Principles Flashcards
Define ventilation as pertains to firefighting operations.
Procedures necessary to effect the redirection and removal of fire elements from a structure
At what temperature can fire gases and smoke from modern synthetic materials readily ignite?
800 degrees to 900 degrees F
What is the most popular form of ventilation?
Horizontal ventilation due to ease and safety of implementation
Define mushrooming.
When the by-products of combustion reach the highest level possible, they bank downward, creating a dangerous environment for suppression personnel
Which fireground hazard, backdraft or flashover, is more common on the modern fireground?
Flashover
Name three primary factors that can be used to evaluate a contaminated environment.
Is there smoke with or without heat?
Is there acceptable visibility?
Are conditions improving or not improving?
What three primary dangers are commonly associated with basement fires?
Weakened floor directly above a basement fire, vertical extension, and safe access to the seat of the fire
What portion of a room is minimally affected by horizontal ventilation?
The upper portions of a room
What primary consideration will set the parameters for ventilation in a multistory private dwelling?
The location of the fire
What portion of a multistory building will be ventilated by opening a penthouse or bulkhead door?
Primarily, that stair shaft and the hallways that open to it
What two categories can our knowledge of ventilation be divided into?
Theoretical
Experiental
When the supply of oxygen is reduced below 21 percent, the production of what gases are accelerated?
formaldehyde, carbon monoxide, acrolein, sulfur dioxide, ammonia, hydrogen cyanide, hydrogen chloride, chlorine, osides of nitrogen, phosgene, isocyanates
What is the primary culprit in fire fatalities as a result of exposure to toxic atmospheres?
Carbon monoxide
Wood products produce ___ BTUs, polyurethane products produce ____ BTUs, polystyrene produces produce____ BTUs
7,000
12,000
18,000
How much fire loss is directly the result of fire?
Less than half
When does backdraft occur?
When oxygen is introduced into a confined area that is pressurized with heated, oxygen-deprived, flammable gases, resulting in an explosion
What is the first phase of fire?
A free-burning fire in a confined building initially has the proper ratio of fuel, heat, and oxygen
What happnens during the 2nd phase of a fire?
Oxygen is reduced, and temperatures, smoke, and cabon monoxide are increased. Oxygen drops to about 17 percent, and temps can hit 1300 degrees
What happens during the 3rd phase of a fire?
Oxygen levels drop (13-15 percent), temps and CO continue to increase. fire smolders
During the 3rd phase of a fire, how much can the expansion of gases and smoke increase?
Factor of 3
What are several distinct trademarks of potential backdraft?
Heavy dark smoke issuing under pressure. turbulent, boiling..
Smoke changing directions or drawn back into structure, sometimes with a whistle
What is the best way to eliminate backdraft?
vertical ventilation
What is Flashover?
The sudden ignition of exposed combustible surfaces or gases in an involved area
What are the differences between flashover and backdraft?
Flashover lacks:
- the sudden introduction of oxygen to a depleted atmosphere
- confinement
- heated flammable gases under pressure
Flashover can drop the oxygen content in a room from 21 percent to what?
4 percent
During flashover, carbon monoxide levels can reach what?
40,000 ppm
Temperatures during flashover can reach what temp at the ceiling?
1800 degrees F
Why can a flashover be more dangerous than a backdraft?
Because of its subtler warning signs
Where are the prime locations of fires in institutions?
Kitchens, lounges, and storage areas
What should be the initial consideration when faced with a fire in a public assembly building?
it should focus on ventiliation operations that will best assist their evacuation
When can you use the HVAC system to ventilate?
only when it has been determined that the fire has been controlled
When can banked elevators be used?
When they terminate at least 5 floors below the reported fire
