An explosion caused by a combination of combustible materials heated to the ignition point and a sudden introduction of oxygen to support combustion?

An explosion caused by a combination of combustible materials heated to the ignition point and a sudden introduction of oxygen to support combustion?

• A. Backdraft
• B. Auto-ignition
• C. Flashover
• D. Detonation

Answer: (A)

Backdraft occurs when a enclosed space has hot, fuel-rich gases produced by a fire that has been starved of oxygen. The flames may be largely hidden, with little visible ignition, but the high heat has pyrolyzed fuels and built up flammable vapors. When a door or window is opened and fresh air rushes in, oxygen rapidly mixes with those gases and a violent combustion happens, often like an explosion. The scenario described—combustibles heated to ignition and a sudden introduction of oxygen to support combustion—fits this phenomenon exactly. It isn’t auto-ignition, which happens without the need for an influx of air; nor flashover, which is the entire room rapidly igniting due to heat, not a sudden oxygen-triggered explosion; nor detonation, which involves a supersonic shock wave typically from high-explosive materials rather than the oxygen surge in a typical structure fire.

Backdraft occurs when a enclosed space has hot, fuel-rich gases produced by a fire that has been starved of oxygen. The flames may be largely hidden, with little visible ignition, but the high heat has pyrolyzed fuels and built up flammable vapors. When a door or window is opened and fresh air rushes in, oxygen rapidly mixes with those gases and a violent combustion happens, often like an explosion. The scenario described—combustibles heated to ignition and a sudden introduction of oxygen to support combustion—fits this phenomenon exactly. It isn’t auto-ignition, which happens without the need for an influx of air; nor flashover, which is the entire room rapidly igniting due to heat, not a sudden oxygen-triggered explosion; nor detonation, which involves a supersonic shock wave typically from high-explosive materials rather than the oxygen surge in a typical structure fire.