What causes 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 a fire backdraft?

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 is the difference between Flameover and 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.

How do you identify a backdraft?

Common signs of backdraft include a sudden inrush of air upon an opening into a compartment being created, lack of visible signs of flame (fire above its upper flammability limit), “pulsing” smoke plumes from openings and auto-ignition of hot gases at openings where they mix with oxygen in the surrounding air.

What are the 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.

What is flashover in transmission line?

A flashover is an electric discharge over or around the surface of an insulator. In electric power transmission, a flashover is an unintended high voltage electric discharge over or around an insulator, or sparking between two or more adjacent conductors.

What is flashover time?

Multiple sources average your time for a flashover to be from 7-10 seconds. So the best-case scenario is you have 10 seconds to react and get to safety. This is usually about 5′ of distance for the average firefighter. The most common signs of a flashover are high heat and rollover.

What are signs of flashover?

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.

What does the term flashover denote?

A flashover is the near-simultaneous ignition of most of the directly exposed combustible material in an enclosed area. When certain organic materials are heated, they undergo thermal decomposition and release flammable gases. An example of flashover is the ignition of a piece of furniture in a domestic room.

Can flashover be predicted?

Trained using data from thousands of simulated fires, the model can predict some flashovers in housefires up to 30 s before they occur. Flashovers are among the most hazardous threats faced by firefighters.

What is meant by back flashover?

Back flashover occurs when the lightning strikes on a shield wire or tower, where the resultant voltage across the insulator is large enough to cause a flashover from the tower to the line conductors.

What is Flashover in a fire?

A flashover is something all firefighters dread, but know they must plan for. Basically, flashover is a cataclysmic escalation of a fire in a contained space, caused when heat radiating down from the ceiling ignites not only the combustible material below, but the airborne gasses released by that material.

What does Backdraft mean?

(plural backdrafts) (firefighting) An extreme fire behavior phenomena involving ignition of products of combustion (such as carbon monoxide ) and pyrolysis products upon introduction of oxygen to a compartment. In this phenomena the fuel generally is at a high temperature (above 600 degrees C), but combustion is limited by a lack of oxygen.

What is electrical flashover?

A flashover is an electric discharge over or around the surface of an insulator. When an electrical flashover occurs, conductors can vaporize, expanding to thousands of times their original volume.

What is a flashover fire?

A flashover is a cataclysmic escalation of a fire in a contained space. A tragic example of this phenomenon occurred on 18 June 2007, when firefighters in Charleston, SC were battling a rapidly spreading fire at the Super Sofa Store, a furniture warehouse.