Foam: Fire Service's Voodoo Science

Mike Wieder dispels the confusion on foam and details its different uses and the types of foam in use today.


In all of my years of fire service response and training experience, I do not believe that I have seen a topic that is any more vague to the fire service than the subject of foam firefighting (other than maybe what color fire trucks should be). There is so much information and misinformation about...


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In all of my years of fire service response and training experience, I do not believe that I have seen a topic that is any more vague to the fire service than the subject of foam firefighting (other than maybe what color fire trucks should be). There is so much information and misinformation about foam floating around the fire service (no pun intended) that it is often difficult for your average firefighter-type person (like me) to determine what is valid and what is not.

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Photo by Mike Wieder
Aspirated foam is applied using a foam nozzle.

In the past year, I had the opportunity to learn more about foam than I ever thought possible. I looked forward to my assignment as the editor/writer of the new International Fire Service Training Association (IFSTA) Principles of Foam Fire Fighting manual with great enthusiasm. Despite the fact that I had been in the municipal fire business for over 17 years and had even done a short stint in petrochemical industrial fire protection, I knew little about how foam really worked. Sure, like other firefighters, I knew all the mechanical basics: how to assemble a foam stream, make sure your proportioner, concentrate and nozzle all match, and things like that. But I was really going through the motions without truly understanding what I was doing or why I was doing it.

The opportunity to work with the IFSTA foam committee would provide me the chance to work with some of the most knowledgeable people on foam firefighting in North America. Included on the committee were representatives of all of the major foam concentrate and equipment companies, fire service people and foam educators. However, in working with these outstanding people, it did not take long to figure out why foam science remains such a mystery to the fire service.

It was clear from the beginning that it would be difficult to gain quick consensus on almost every issue we wished to address in the manual. Each of the major foam manufacturers has its own ideas about how its products should be used and they are very protective of those ideas. In the foam business, there is little consensus about what flow rates should be used, methods of application, acceptable nozzles to use and general firefighting tactics using foam. This is certainly not meant to be a negative shot at the manufacturers. Each has gone to great lengths to develop and test its products. Unfortunately for the fire service, the manufacturers tend to come to different conclusions on how to use their products. They also tend to dispute the others' claims for their products. None of them particularly agree with the figures provided in NFPA 11, Low Expansion Foam Extinguishing Systems.

This leaves the fire service in a precarious position. For example, suppose you are the chief of a fire department that has never before had foam capabilities on any of its apparatus. Now you are buying a new pumper and wish to have an onboard foam system added to the rig. The apparatus manufacturer will likely give you four or five choices for types of foam systems that can be used to dispense the concentrate from the 30-gallon concentrate tank you have specified. In reviewing the various manufacturers' literature, and perhaps even talking to manufacturers' reps, you get a variety of opinions about which system is the best. You will probably also get a variety of answers on how much fire 30 gallons of concentrate will put out. The decision of which foam system to pick turns out to be not as easy as you thought.

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Photo by Mike Wieder
Nonaspirated foam is applied using a fog nozzle.

And then it gets worse. Now you have to decide which foam concentrate to put in your tank. The manufacturers have different information on what the required flow rates should be, what proportioning percentage to use on a certain fuel, and what type of nozzle can be used in a given circumstance. Your head spinning, you decide to contact the instructor at your county or state fire academy to get an "unbiased" opinion. You soon learn that unbiased opinions are hard to find. Most of these instructors have been taught what they know by one of the foam manufacturers (usually the one that gives or loans them equipment for their school and sells them training concentrate at the lowest price). The instructors do not have an across-the-board, generic understanding of foam principles.

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