The complicated confluence of firefighting techniques, training, tactics and practice is difficult to model. That is to say that it is hard to create a repeatable situation where one can isolate one variable from the next and come to some realistic conclusions as to the “right” answer.
In many ways this statement lends credence to those who argue that laboratory experiments, no matter how well-funded or how well-instrumented, cannot be practically applied to the so called “real world” firefighting situations.
Despite the complexity however, it is critically important to take the laboratory work and apply it as much as is possible to the real world because some things are true whether we can model them in their entirety or not. Let’s examine three key points from recent fire research and one from the annals of common sense and consider how they can be applied to the real world.
Flow Paths
They say that the modern fire environment certainly has the potential for creating some spectacular fires. What limits the creation of a spectacular fire is the lack of oxygen. Given enough air even a small fire, one that would only take a few gallons of water to extinguish, can turn into a raging inferno, frying everything in its path.
The key word here is path. As powerful as the wind can be it has its limits too. For the wind to do its terrible thing it has to have a pathway. There has to be an entrance and an exit.
If there is only an entrance or only an exit, the wind cannot kill. Of course, the fireground is a complicated place and there is always something that can intervene and hurt you, but for it to be the wind you need an entrance and an exit.
All points lying between the entrance and the exit are collectively called a flow path. A flow path is something to avoid at all costs.
Speed
“The dominant flows in this plane are the fresh air entering the open basement doorway at approximately 4 m/s (10 mph) and the hot gas flow exiting the upper portion of the doorway at approximately 7 m/s (16 mph).”
They say that if you put a live frog into a pot of cold water and turn on a burner underneath it, the frog will allow itself to boil to death. By the time the frog realizes that it is in danger, the danger has already passed the point of no return. Frogs are geared to notice sudden changes in the environment.
They say that the cheetah accelerates from 0 to over 60 mph in three seconds. At least, that’s what Wikipedia tells us. Firefighters sometimes sit like frogs when they should run like cheetahs.
The rate of change when a fire goes to flashover or to other severe fire-behavior conditions is exponential. That means that the first clue that something bad is going to happen is that something bad already happened.
The previous quote about the speed of air entering and the speed of hot gasses exiting come from the National Institute of Standards and Technology report examining a May 1999 fire on Cherry Road in Washington, D.C.
The Cherry Road fire teaches us that unless you are a cheetah with an unobstructed path to the outside and you know the fireball is coming up the steps, you will not be able to escape it. The report says that even if the cheetah started to run when it felt the wave of heat, it still would have died.
The only thing that can save firefighters is thinking and acting like people, by predicting future states and avoiding trouble in the first place.
Water
They say that Nero fiddled while Rome burned. Even the Romans knew that a little water applied to the burning surfaces would have been a more effective approach.
The scientists and engineers who study such things say that the seat of the fire — that elusive thing the aggressive interior attack hopes to find — is wherever the flames are exiting the structure.
The primary risk for the civilian in a burning structure is exposure to the carbon monoxide that is being created by a fire burning uncontrolled and under-ventilated. As long as the fire burns, it consumes oxygen, creates heat and creates carbon monoxide.
They say that the second we begin to apply water to a fire the rate of its burning is reduced, the amount of heat it can generate is reduced, and the amount of carbon monoxide it can make is reduced.
Again, the primary risk for the person trapped inside a burning house is the risk of being asphyxiated. The second we begin to apply water the risk is reduced. Water makes everything better.
Common Sense
Residential fire sprinklers save lives. They save lives by spraying water down from the ceiling onto burning surfaces.
They do not charge in the front door, down the throat of flow paths and into the door of the burning room. They do not smash windows or cut holes in roofs. They don’t spread fire by their fine spray.
They save lives before the fire department can intervene.
The first best hope for civilians is never having a fire — we can teach them that. Their second best hope is a smoke detector with a working battery to give them time to get out — we can train them to do that. Their third best hope is a sprinkler system to keep small fires small — we can legislate that.
Firefighters are the last hope, almost the final act of desperation. And every day the challenge of municipal budgets conspire to increase their response time, decrease their staffing, and almost ensure that the final act of desperation is doomed to fail.
