A violent and sudden deflagration that occurs in a confined, ventilation-limited fire. The room contains high concentrations of superheated, unburned fuel gases that have consumed the available oxygen. When a door or window is opened, fresh air rushes in, mixing with the gases and causing an immediate, explosive ignition that blows outward.
Heard on the job
The windows are blacked out and puffing smoke, so watch out for a backdraft if you force that front door.
Insider tip
Warning signs include yellow-brown smoke puffing from eaves, windows stained black with soot, and a lack of visible flame despite high heat.
Do not mix it up with
- Smoke explosion: A backdraft requires a sudden introduction of oxygen to a smoldering fire, while a smoke explosion is the ignition of pre-mixed gases that travel to an ignition source.