When is using foam on fire the right tactic? The short answer is it's never a bad idea to use foam on a fire.
So says Mark Cummins, who invented the Compressed Air Foam System in 1976. While Cummins invented CAFS and at one time had the patent for CAFS in just about every English-speaking country, those patents have expired and anyone can manufacture a CAF system.
"The biggest problem that I see with firefighters and the use of foam is that firefighters don't understand foam," Cummins said. "They don't understand the foam, how to make it and how to best use it."
Most of the fire service's knowledge and understanding of foam comes from the use of foam in military and industrial settings, Cummins said. "That generation of firefighters learned about the use of foam in dealing with flammable-liquid fires where the desired outcome was to remove the oxygen from the fire using the foam's ability to put a barrier in place to cut off the oxygen supply.
"Many years ago when I was working with the Texas Forest Service on ways to use foam for forest fires, I encountered a lot of resistance. But when we stared calling it 'expanded water' — and that's what you're doing with foam — that changed a lot of people's minds," he said.
All firefighters should know that we use water on structure fires to remove heat from the fire triangle by absorbing the heat in the room and cooling the available fuel. But do you know that roughly 90 percent of the water hits the floor after passing through the room's atmosphere, and that includes the water that hits the target?
That's right, only about 10 percent of the water is penetrating the fuel to absorb heat and cool the fuel below the temperature required for sustained burning.
CAFS uses a Class A foam concentrate, combined with water and compressed air to form a fire extinguishing agent that is greater than the sum of its parts. The synergistic effect is a product with greatly reduced surface tension compared to that of plain water, which enables the solution to penetrate burning fuels much faster and more efficiently.
CAFS offers several advantages over plain water that have been verified in multiple research tests.
For example, when used according to manufacturer's recommendations, a CAFS fire stream has a 20-1 expansion ratio. That means that for every gallon of water being used, 20 gallons of finished CAFS solution is delivered to the fire.
Also, the surfactant in the CAFS fire stream creates a thin film that sticks to wall surfaces and the target fuel where it continues to absorb heat. Even the CAFS that winds up on the floor is absorbing heat 20 times more efficiently than plain water.
And, the surfactant in the CAFS fire stream is chemically attractive to the carbon molecule contained in smoke. Every molecule of the CAFS solution that comes in contact with smoke binds a molecule of carbon.
That last point becomes more critical as we learn more about the connection between the carcinogens in the products of combustion and the increased cancer risk for firefighters as compared to the general population.
"The sooner firefighters start applying CAFS to a fire, the sooner they start mitigating that risk to themselves and the downwind civilian population," Cummins said. "So anytime you want your available water to do more with less, you want to be using CAFS."
In many parts of the United States water is becoming an increasingly scarce and therefore a precious commodity. One of the prevalent arguments against the use of CAFS is that those systems are expensive: they add to the cost of new apparatus and the foaming agent costs money — water is typically considered free.
But really, how free is water in communities across states like California, Texas and other regions that have been experiencing historic draught conditions for many years now? Even in communities not stricken by drought, there's an associated cost with processing, storing and delivering water.
If you can get 20 gallons of finished CAFS in a fire stream using 1 gallon of water, how is that not a good return-on-investment?
The fire service needs to examine the facts regarding CAFS and consider making the CAFS the first tactical fire stream for interior structural firefighting. Here are five reasons why.
- CAFS reduces the amount of water used for fire suppression.
- CAFS reduces air pollution and reduces firefighter exposure to airborne carcinogens.
- Because CAFS reduces the amount of water used, it reduces the amount of water pollution from water runoff.
- CAFS reduces property damage from water damage since there's less water used.
- CAFS reduces firefighter safety risk.
Let's expand on that last point. Quicker knockdown time means fewer fires will reach flashover stage. Faster reduction of interior temperatures means fewer fires where firefighters are exposed to high interior temperatures
And those are good things.
There is also a reduction of firefighter fatigue and resultant sprain and strain injuries incurred while advancing hose lines for fire attack. CAFS hose lines are much lighter and more maneuverable than conventional hose lines because 80 percent of the hose's contents are air bubbles.
So the question should be: Why are we not using foam?