There are a variety of foam concentrates available to the fire service. Some are more specialized than others and some are more common. In order to give company members a working knowledge, we’ll give a brief overview of the different types of foam concentrate and some of the “buzzwords” associated with foam. If you want more information, the major manufacturers have an enormous wealth of information available for free on the web. Take a look at the references at the end of the first part of this series.
Chemical Foam was the mixing of powdered chemicals that together created a finished foam product. Sometimes these chemical additives were referred to as Chemical A and Chemical B. It’s important not to confuse this nomenclature with other vocabulary such as Class A and Class B foam concentrates.
With chemical foam there was no single concentrate that was easily added to a hoseline. The two chemical powders were added via a hopper directly into the hoseline. Because of its difficulty in use, and less than perfect quality, it is no longer used in today’s fire service. Chemical foam was replaced by mechanical foam decades ago.
Mechanical Foam is the common product we deal with on a daily basis. Mixing water, foam concentrate, and air in the proper ratios to produce a finished foam blanket creates foam. The three ingredients are mixed via a mechanical process and do not require a chemical reaction to achieve a finished foam blanket. Our studies will primarily be concerned with the correct mixing of these three ingredients and applying the finished product effectively.
There are a variety of foam concentrates on the market today. Depending on the manufacturer, you may find differences in the specific details associated with each concentrate, so make sure you know the specifics of what your department is using. In this series of articles, we’ll offer a very generic look at some of the more common types of concentrates and equipment that can be used, but for specific details, consult the manufacturers.
Protein Foam was an original type of liquid concentrate that was made up of organic materials and other additives. When used to attack a flammable liquid fire, it had a good resistance to heat, but its use was limited to hydrocarbon spills and fires. It is not in use in any great quantity in the municipal fire service any more. Other types of concentrates have replaced protein foam. These more modern concentrates have additional features such as greater fuel shedding properties and the ability to be used on both hydrocarbon and polar solvent spills and fires.
Film Forming Fluoroprotein (FFFP) and Alcohol-Resistant Film Forming Fluoroprotein (AR-FFFP) build upon the benefits of protein foam and protein foam’s successor, Fluoroprotein foam. With synthetic additives as part of the concentrate, these concentrates can be used on fires and spills involving hydrocarbon fuels. With additional additives, these foams can be designed as an alcohol-resistant type of concentrate allowing them to be well-suited to incidents involving polar solvents. FFFP foam has the added benefit of being able to apply a very thin film over top of the spill, thus preventing the release of flammable vapors from mixing with air. With proper application, these types of foam concentrates offer a finished foam that is longer lasting, has good fuel shedding ability, and has good resistance to heat.
It also has similar features to AFFF (see below) in that a film floats ahead of the spill to create a layer that separates the fuel from the air. This concentrate can be used with both fresh and saltwater for even greater versatility. Check with the manufacturer as it relates to freezing and thawing (some sources say the concentrate can be affected by freezing and thawing, while other sources say the opposite). This agent is also compatible with dry chemical extinguishing agent in the event a coordinated attack is required.