Product Code Database
A backdraft (North American English), backdraught (British English) or smoke explosion is the abrupt combustion of superheated gases in a fire caused when oxygen rapidly enters a hot, oxygen-depleted environment; for example, when a window or door to an enclosed space is opened or broken. Backdrafts are typically seen as a blast of smoke and/or flame out of an opening of a building. Backdrafts present a serious threat to . There is some debate concerning whether backdrafts should be considered a type of flashover.
If material undergoing pyrolysis is later given sufficient oxygen, the hydrocarbons will ignite, and therefore, combustion takes place.
The colour and movement of smoke is used by firefighters to infer fire conditions, including the risk of backdraft. Characteristic warning signs of a backdraft include yellow or brown smoke, smoke which exits small holes in puffs (a sort of breathing effect) and is often found around the edges of doors and windows, and windows which appear brown or black when viewed from the exterior due to soot from incomplete combustion. This is an indication that the room lacks enough oxygen to permit oxidation of the soot particles. Firefighters often look to see if there is soot on the inside of windows and in any cracks in the window (caused e.g. by the heat). The windows may also have a slight vibration due to varying pressure within the compartment due to intermittent combustion.
If firefighters discover a room sucking air into itself, for example through a crack, they generally evacuate immediately, because this is a strong indication that a backdraft is imminent. Due to pressure differences, puffs of smoke are sometimes drawn back into the enclosed space from which they emanated, which is how the term backdraft originated.
Backdrafts are very dangerous, (1998). 9780879391492, International Fire Service Training Association. ISBN 9780879391492 often surprising even experienced firefighters. The most common tactic used by firefighters to defuse a potential backdraft is to ventilate a room from its highest point, allowing the heat and smoke to escape without igniting.
Common signs of imminent backdraft include a sudden inrush of air upon creating an opening into a closed compartment, no visible signs of flame in a hot compartment (fire above its upper flammability limit), "pulsing" smoke plumes from openings, and auto-ignition of hot gases at openings as they mix with oxygen in the surrounding air.
In the film adaptation of Stephen King's 1408, the protagonist Mike Enslin induces one as a last-ditch effort to kill the room.
The term is also used and is the title of a scene in the 2012 video game .
In the second book of the light novel series Imperial Reincarnation: I Came, I Saw, I Survived, the character Carmine uses a magically produced backdraft to defend himself against an assassination attempt.
|
|
