Kitchen Table Debriefs - Hostile Fire Events (Part II)
Edward M. Raposo
How Are Hostile Fire Events Similar
Hostile fire events share some similarities:
•Intense heat coming from the compartment
•Heat pushing smoke (making it appear boiling or turbulent)
•Thick, black smoke (carbon laden, and very ignitable)
•Little time between seeing these indicators and the event occurring!
•Sometimes you get a heads-up, sometimes you don’t
•They should scare the crap out of you
•They are dramatic
Goodness, Gracious! Great Balls of Fire!
With flashovers, you may get a dramatic fireball. This is sometimes confused with an explosion, and, therefore the event is incorrectly labeled a backdraft.
This YouTube video appears to be an example of a flashover labeled as a backdraft.
How Are Hostile Fire Events Different
Hostile fire events have some differentiators.
What causes them: Flashovers are triggered by massive heat build-up. The container cannot absorb any more heat. The heat in a room has nowhere else to go, so it feeds back onto itself, raising the temperature in the compartment to the temperature where everything auto-ignites. Backdrafts and smoke explosions are triggered by oxygen re-introduced to an oxygen-starved, superheated, highly flammable environment.
What phase of combustion they occur in: Flashovers can only occur at the end of the growth phase beginning the free burning phase. Backdrafts can occur anytime there is a smoldering fire during the growth or decay phases.
What kills: Flashovers are rapid combustion and the heat kills. Backdrafts are instant combustion and the blast kills.