The Fire Decagon and Fire Behavior

08/28/2019

By Jerry Knapp

Just like you, in my recruit class we learned about the fire triangle. Then, the well-intentioned instructor shared the mysterious chemical reaction side, making it a tetrahedron. We were taught that by “breaking one of the sides” we would extinguish the fire. There we were, all smiles, eager for our first fire. It was so simple, we could quickly, easily vanquish the red devil, the evil dragon, take away the heat with a sweep of our nozzle. It worked every time in training fires. Then we went to a real fire and found out it was a little more complicated.

Soon after recruit school I went to two house fires that provided some significant post-traumatic motivation and growth: three dead kids in one fire, a entire family of five in another. It was not so simple, and I instantly learned that it was a really serious game. Years later, at FDIC, Chief Brunacini would accurately describe fire as: “A mutual murder contest, the fire shows up to kill everything, and you show up to kill the fire.”

So I studied private dwelling fires to become a master of my craft (or at least better at it) and learned the following: House fires are 75 percent of working fires, loss of life, injuries and dollar loss in the US to fire. Residential fires are our most important alarm.

I taught house fire strategy and tactics at our training center for years. I faithfully passed on what was taught to me. Thanks to the UL and NIST work we now have data, facts, measurements, and observations of the critical factors and conditions that dictate the fire progression for house fires and on which we can base our strategies and tactics. Based on this new knowledge, I have modernized and improved some of the tactics and strategies I taught for years.

The interior search team does not prop the door open anymore; command makes sure water is coming in front of, concurrently or immediately behind them; we don’t take the windows until the line is in place and close to or actually flowing; we don’t climb down the “chimney” (interior stairs) if we don’t have to for basement fires; we sometimes apply water from the outside when it is tactically appropriate, then quickly get inside and get it; and we move the nozzle in circles a bit slower.

 In 2014, I was very fortunate to be selected to the UL tech panel for the research titled, ”The Impact of Fire Attack Utilizing Interior and Exterior Streams on Firefighter Safety and Occupant Survival.” Working with and just being around folks like Steve Kerber, Dan Madrzykowski, Robin Zevotek, and Keith Stakes, and having access to the wealth of knowledge and experience of the other tech panel members, was priceless. The complexities of these deadly fires became a bit clearer. The question became how to demonstrate this or at least open the minds of those smiling and eager faces in the probie classes. I developed the “fire decagon,” which incorporates a few of the complexities we examined in the study.

Clearly, a static,10-sided, one-dimensional figure is inadequate to represent the fire dynamics of a modern house fire, the interactions of our ventilation and fire suppression, and the exotic chemical reactions that are going on in a house fire. It is, however, a huge step forward from the fire triangle, especially for our recruits. It will hopefully get them started on the right foot and perhaps sway some of the naysayers.

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