So you're in charge of a company and you start thinking about a list of the top five things you never do, to discuss with your company members. One of those top five is the passed on from generation to generation: "You never spray water into smoke" and you begin to think about this one in particular.
The critical statement, "We never ever spray water into smoke regardless of anything," suddenly comes to mind. If you analyze your past experience, you think about the times you were advancing a handline down a hallway and finding the heat was pushing you to get lower to the floor each step forward.
You know the heat is from either a growing fire or you're closing in on the base of the fire. Next you understand the heat is contained within the smoke and one of a few things will occur:
- You locate the fire and extinguish it thus the smoke begins to cool
- The truck company ventilates and the smoke rapidly exits the structure
- The smoke will continue to absorb the heat and a flashover ensues
- The oxygen will become depleted and unable to sustain combustion until either the environment cools or fresh air is induced creating the potential of a back draft.
What we really are concerned with in this discussion is number three. As the fire continues to grow it will generate heat and that heat is absorbed by everything within the location of the fire. Once all those materials, including the smoke, have absorbed as much heat as possible, all those materials will ignite and combust.
This is the heart of our discussion about smoke and water. If the smoke has absorbed as much heat as possible, and a flashover is about to occur, you must induce water into the smoke to cool it and allow for it to absorb more heat. By doing this you can prevent or delay a flashover and allow yourself more time to find the seat of the fire or exit the building before sustaining serious injury or death from a flashover.
The rule of never flowing water into smoke should be clarified as never flow water into cold smoke! The reason for this is the particles of smoke can absorb the water and become less buoyant. In other words the smoke will fall to the floor and obscure visibility. But with high heat smoke, this is less likely to occur and if it did, that's much better than fighting your way out of a flashover. It is understood that typical room contents will flashover at approximately 1000 F.
At tests conducted during the 1960's in California it was determined that, at temperatures between 280 F and 320 F the skin will be injured starting with pain. So if we put all this together we begin to realize that high heat smoke must be treated different than cold smoke and inducing water into high heat smoke can prevent serious injury or death due to flashovers.
Now, we are not talking about opening the nozzle wide open and flowing water until the water department requests you to shut down, but short bursts of water to the point you can feel a reduction in heat.
As the company officer in charge, you must now determine if your company can move in and knock it down or if you must retreat to a safer location. Understanding high heat smoke will allow you and your company to operate safer and return home without unnecessary injuries.
JEFF JOHNSON, a Firehouse.com Contributing Editor, is a captain with the Kansas City, MO, Fire Department and is assigned to Pumper 35. He is a 19-year veteran of the fire service, and is a member of the International Association of Fire Fighters Health and Safety committee and Joint Chair for the Kansas City, MO, Fire Department Health and Safety committee. He has partipated the Training & Tactics Talks podcasts on Radio@Firehouse.com. To read Jeff's complete biography and view his archived articles, click here.