This is the first bulletin in a two-part series on flashover and backdraft. In Part 1: Flashover, you will learn why situational awareness is critical for recognizing when potential flashover conditions exist.
Learning to recognize when flashover conditions exist can save your life.
Flashover is a thermally-driven event during which every combustible surface exposed to thermal radiation in a compartment or enclosed space rapidly and simultaneously ignites. Flashover normally occurs when the upper portion of the compartment reaches a temperature of approximately 1,100 °F for ordinary combustibles. Building features like concealed spaces, lower ceiling heights, room partitions, and energy-efficient or hurricane windows are more likely to contribute to flashover conditions.
Factors that influence a flashover event
- Location of fire.
- Size, volume and shape of compartment.
- Fire growth rate.
- Contents and their exposed surfaces.
- Compartment ventilation characteristics.
Factors that influence responder exposure
- Arriving on the scene at a pre-flashover state.
- Compartments are built tighter with fewer sources of air leakage.
- Bunker gear provides a false sense of security.
- Rooms filled with many more synthetics that flash at lower temperatures.
Signs of an impending flashover
- Ambient temperatures quickly double and triple as hoselines are advanced.
- Large volumes of heavy dark smoke.
- Rollover: active flame circulation in the thermal layer.
- Free burning fire in a ventilation-deficient environment.
Uncoordinated ventilation caused flashover killing Illinois firefighter
Investigators say crews failed to recognize signs of an imminent flashover; firefighters were between the fire and ventilation points.
Read about this fatal flashover
and safety recommendations for fire departments to follow.
Steps to protect yourself
- Always plan an evacuation route.
- Cool the area as soon as possible: fog pattern into the upper thermal layer.
- Switch to straight stream to cool contents and create a buffer zone.
- If conditions worsen despite your attempts to cool the room, get out and reassess the situation.
Michael Salzano, battalion chief, Fort Lauderdale Fire Department, offers these additional notes:
- Not all fires progress to flashover, but every fire has flashover potential.
- Have an exit strategy. If you are inside the building 10 feet or 100 feet, have a plan and consistently communicate that plan to each other.
- Situational awareness is essential; don’t get tunnel vision and miss the signs of flashover.
- Communication between interior crews and command is most important. Notify command of any changes in fire, smoke or heat behavior.