How do you explain a flashover?
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.
What is rollover in firefighting?
If the fire becomes hot enough, one or more of these gases will reach its ignition temperature, igniting the cloud of fuel. This is flameover, also called rollover, due to the physical manifestation of “rolling” of flame across the ceiling as the gas layer ignites.
What is the difference between a rollover and a flashover?
Rollover (also known as flameover) is a stage of a structure fire when fire gases in a room or other enclosed area ignite. Rollover is not the same as flashover, although it may precede it, and the terms may be confused. In the case of rollover, only gases present in the room, not the room contents, ignite.
What is flashover and backdraft?
A backdraft is an air-driven event, unlike a flashover, which is thermally driven. Backdraft is usually defined as a deflagration resulting from the sudden introduction of oxygen into a ventilation-limited space containing unburned fuel and gases.
How do backdrafts happen?
A backdraft is caused by the sudden introduction of air into a fire that has depleted most of the available oxygen in a room or building. When a fire has depleted most of its oxygen, the flames will die down, but the fuel will still burn in a smoldering state and still generate heat, like with charcoal.
What do you do during a flashover?
Temperatures during a flashover often exceed the PPE limitations. Also try to always consider alternate egress points or areas of potential refuge which could include doors, windows or adjacent rooms. Be proactive, read the smoke, study the fire and if you see something report it.
What is the difference between backdraft and smoke explosion?
The smoke explosion is a separate phenomenon to backdraft which requires a change in the ventilation. For a backdraft to occur there must be a change in the ventilation such as a window breaking or a firefighter opening a door as they enter the compartment.
How can flashover happen?
Flashover occurs when the majority of the exposed surfaces in a space are heated to their autoignition temperature and emit flammable gases (see also flash point). When the temperatures of the evolved gases become high enough, these gases will ignite, throughout their extent.
What are signs of flashover?
Signs of room flashover include:
- High heat conditions or flaming combustion overhead.
- The existence of ghosting tongues of flame.
- A lack of water droplets falling back to the floor following a short burst fog pattern being directed at the ceiling.
Are backdrafts real?
Are backdrafts common?
Backdrafts are very dangerous, 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.
Is a result of flash over?
Flashover occurs when the majority of the exposed surfaces in a space are heated to their autoignition temperature and emit flammable gases (see also flash point). When the temperatures of the evolved gases becomes high enough, these gases will ignite throughout their extent.