What is the difference between flashover and backdraft

The fire will grow until the air is consumed and smouldering may continue for some time. The room may stay quite hot and the combustible contents will continue to pyrolyse or breakdown allowing the accumulation of large quantities of unburnt fuel. If an opening is created air will flow into the compartment and add the missing ingrediant. It is possible for a sudden and explosive propagation of flame through the compartment and out through the openings.

There will be pockets of gas remaining that are too rich to ignite immediately these will burn progressively as air is drawn into the compartment. The combustion process could continue for some time after the initial explosion and the heat generated could lead to a fully involved fire. In a nutshell, backdraft occurs when air is added to a room with high temperatures and large quantities of unburnt fuel. So how does this knowledge affect our fire attack strategy and hose lay tactics?

Before we talk about that we must understand the 3rd critical fire development event, fire gas ignition. Shan, As you know, Lasse Bengtsson made a great work a few years ago, which resulted in the book "Enclosure fires". He looked a various definitions of flashover and backdraft and there are some great explanation in the book. I can strongly recommend this book I know for sure Shan's got a copy It can be found here assuming the technology works Check out the following video to see a backdraft in action:.

These three circumstances are incredibly dangerous to get caught in, and you are unlikely to survive. Make fire safety one of your top priorities and make sure you own every kind of fire safety equipment.

A smoke detector to warn you of the fire, a fire extinguisher to fight the fire, and a SkySaver when you run out of options and must flee the fire.

Check out the following video to see these three situations as they develop in a simulator: Rollover — A rollover is the circumstance in a structure fire when incompletely burned fuels or ignited fire gases spread out horizontally after rising to the ceiling. Check out the following video to see a rollover in action: Flashover — A flashover is the circumstance in a structure fire when everything in the room suddenly and simultaneously ignites.

Check out the following video to see a backdraft in action: These three circumstances are incredibly dangerous to get caught in, and you are unlikely to survive. All rights reserved. All members on the fireground must know the warning signs of backdraft. Chiefs or their aides setting up a command post across the street are most likely to see that kind of smoke.

If backdraft conditions are suspected, proper ventilation will prevent the explosion. Openings must be made above the fire to allow the superheated gases to escape before oxygen is introduced at lower levels-the lower levels where we would be entering.

Backdrafts and flashovers are equally dynamic and deadly. Recognizing the signs and being able to remain calm will give you the best chance for survival. It goes without saying that you should be in full protective equipment. A fire on a lower floor of a multiple dwelling could extend heat and smoke throughout the fire building.

This smoke would get trapped in the cockloft, the space between the top-floor ceiling and the roof. Members sent to check for extension would pull the ceilings and allow oxygen to enter the cockloft, and the hot gas would mix with air and the cockloft would backdraft. How did this occur? Knowing what we know about carbon monoxide CO today, the space was probably filled with CO. Remember, in addition to its other dangerous properties CO is flammable. What does this mean to us as firefighters?

CO will burn at a relatively low temperature for fires anyway and at almost any mixture. When sent to check for extension, make a small examination hole first. Make this hole from the doorway, and make it small at the start. Poking a small hole will limit the amount of oxygen that enters the cockloft or other enclosed space. If you let enough air into the space to ignite the mixture of gas, you will be standing in a position of safety in the doorway. If you pull a large section in the middle of the room and the cockloft lights up, the whole ceiling will drop on your head.

If your examination hole indicates some fire may be present, call for a line before any more of the ceiling is pulled. Remember, you were sent to find fire. If you find it, what will you accomplish by exposing all that fire with no way to put it out? The only way to protect firefighters is to train in understanding the fire environment. It goes without saying that you should be in full protective equipment. Back Draft , when fire consumed all the oxygen in enclosed area leaving heat ,fuel ,when sudden entrance of the air in this enclosed area the fir again start in the form of explosion.

Air Oxygen play an important role in back draft. Flash Over, flash over happen when enclosed area the temperature reach at the fire burning level c' or f ' all the thing start to burn simultaneously this is called flash over , Heat play an important role in flash over.