Let's Talk Fire: What Is A Flameover Fire
What is a flameover fire?
Ask a firefighter to define backdraft or flashover and you will quickly receive a response containing the definitions in no time, well unless of course you asked a probie the question. If you posed this question to an old dog in the service you most likely received the answer and a story to go along with it. Now ask these devoted men and women to define the term flameover. You will most likely be introduced to wide eyed stares and blank expressions. This is a big deal because despite not getting the same attention as the ever elusive backdraft and the disastrous flashover, the flameover is equally deadly to firefighters and has the same threat threshold of property loss as it's counterparts.
The National Institute of Standards and Technology (NIST) define flameover as the rapid spread of flame over the surface of a wall, ceiling, or floor. Sounds simple enough but what the definition leaves to the imagination is what causes a flameover and better yet how can we as firefighters avoid them.
Flameover was first used in the 1946 fire at Winecoff Hotel in Atlanta GA to describe what firefighters were reporting during their initial entry into the building.
Getting to know our foe.
Flameover falls into a category of known as flash occurrences. These occurrences include rollover, flameover and of course flashover. As with any of these occurrences they can occur in a "flash" with little warning. Since flameover can occur instantly and spread at a very rapid rate it is vital that we as fire behavior firefighters train to recognise the signs of a flameover and know what we can do to avoid being caught in the burn. Knowing how to anticipate this type of fire activity could save your life. Let's take a closer look at this fire ground anomaly.
As most firefighters know it is not the fuel itself that burns, but the vapor the fuel produces. Take wood for example, as it becomes heated it begins to emit a vapor that is flammable and the vapor begins to burn using the wood as a fuel. Flameover occurs when the covering of a surface, be it a wall, a ceiling, or a floor becomes hot enough to ignite. When the vapors ignite it causes the flames to spread rapidly over the surface. This rapid spread of fire through walls and ceilings can cause a firefighter to become trapped and lose their means of egress.
Understanding the cause
Flameover was a huge threat during the years after World War 2. Wall coverings had become much more elaborate than simple paper. Accents such as fur or cloth made the paper more attractive but also much more acceptable to flame and heat. This new wallpaper would heat up much faster than the previous coverings and thus increase it's rate of flash and within a very brief period of time the wall would experience flameover.
Sure one might say it is not a common thing for us in today's day and age to approach fuzzy wall paper but let's look at the componants of today's wall paper and other wall coverings and you will start to see why this is still a huge threat to the everyday firefighter.
Wall paper is just that, paper. It is highly combustible, very quick to burn and can heat the surrounding area in a very little period of time. That alone makes it dangerous in my book, but let's factor in glue. Most glues used to adhere wall paper are flammable and some are extremely so. This combination of glue and paper is idea for a good burn to progress. This is made worse by the fact that some of the manufacturers who craft this paper use heavy inks that are just as dangerous as the glue.
But let's not stop there what about most walls we encounter? In our field nowadays we see mostly sheetrock (gypsum) walls. These are not as bad for flameover and usually will be up to the bar when fighting the spread of fire, but we have all encountered rooms in which paneling is the means of wall covering. Paneling is basically kindling in the eyes of a fire and will burn at an alarming rate. Take into consideration that a lot of home owners will varnish or stain the paneling they just got on sale. This is a recipe for disaster just waiting to brew itself up. Paneling is a very dangerous wall covering in a fire, it will produce flameover situations without much warning.
Not just the walls
Ceilings and floors are also prime locations for the flameover to occur. The most likely cause is treated hardwood floors. These have become all the rage with trendsetting home owners and interior decorators. They look good, last forever and make your home stand out to the average Joe. What stores don't tell you is that long lasting home improvement you made is also a huge fire hazard. Most floors of this nature are treated with varnish or stain. It gives it luster, makes it shine and also increases the rate at which it will burn.
The treatment on these types of floors creates an environment that will produce more flammable vapor more quickly and thus trigger the flameover mush faster than a traditional style floor would allow. It is vital to understand the make up of each room you are entering and know how you will get out if you had to do so in a hurry and let's face it, as firefighters we usually are always in a hurry.
Ceilings are also very dangerous when special treatments and accents have been added. Recently a growing trend here where I live is theaters using velvet on their walls and ceilings. This is a nightmare for the firefighters who would have to go in and deal with a fire in that area. We have to understand how rooms are composed before we make entry into them and risk losing our life.
Hazards to consider
As with any situation on the fire ground there are a number of hazards to take into consideration. Flameover presents us with a few of it's own. One factor is the fire can spread across a wall and get behind a firefighter advancing a line or doing a search operation. This can cause the firefighter to become trapped within a wall of flame. None of us want to be in that situation. Flameover may also sneak up on us. While we are operating on a floor we may be unaware of the fire in the wall or under us. As flames continue to heat the various surfaces in the room vapors are emitted and wham! flameover. This makes it a very deadly foe indeed as we may be unaware that it is going on until it is to late to really react to it. I am often asked how to best avoid this situation and my response is simply take off your blinders and pay attention to the surroundings. Always have a means of escape.
If we are trained to look for more than one means of escape we will be much better prepared to deal with a situation that may allow a flameover to occur. We will not be caught to far off our guard to react and save ourselves and our brothers and sisters.
- Flameover occurs when walls, ceilings, or floors ignite simultaneously
-flameover can trap firefighters in a wall of flame
-flameover may occur as a direct result of a fire you have no visual on
-training for flameover occurrences can save lives and property
-flameovers are just as dangerous as any other flash occurrence
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