Authors: Norbe Puroll and Mark Siem, Perimeter Solutions
Firefighting is a dynamic and demanding profession that requires constant adaptation to evolving fire threats. While water remains a fundamental tool, the strategic application of foam can significantly enhance firefighting capabilities. By understanding the differences in various foam technologies that are available, firefighters can optimize their response strategies, mitigate property damage, and protect lives. In this article, we explore the benefits of Class A and Class B foams and how they can support firefighting tactics.
Class A Foams
Class A foams are specially formulated to make water more effective for firefighting. The foam has a number of applications, including structural firefighting, vehicle fires, nuisance fires, tire fires, wildland firefighting, and prescribed burns.
Developed using special surfactants, Class A foam significantly reduces water’s surface tension, and when mixed with air, it creates a superior foam blanket that surrounds fuels. This creates a barrier between the fuel and the fire, knocking down the fire faster than water alone, and allowing firefighters to see the areas of application.
In addition to decreasing the time to extinguish a fire, Class A foam limits water damage from battling a fire and results in a reduction in mop-up/overhaul time. Some other key benefits:
- Reflects radiant heat and is highly visible
- Insulates fuels and excludes oxygen
- Absorbs maximum BTUs due to its large surface area
- Clings to vertical surfaces and acts as a water reservoir
- Penetrates water into fuels because of its low surface tension
Class B Foams
While Class A foams excel at suppressing fires involving common combustibles, Class B foams are engineered for tackling more specialized fire scenarios involving flammable liquids. They are typically used in chemical and petrochemical plants, refineries, oil and gas storage facilities, flammable liquid storage facilities, airports, and anywhere flammable liquids are stored. Due to the nature of these fires, blanket integrity can be compromised, and it is important that the foam used has good burnback resistance in order to minimize the spread of fire.
In recent years, the industry has started to transition to fluorine-free foams to replace the aqueous film-forming foams (AFFF) that have been used to suppress fires for nearly six decades. Fluorine-free foams not only align with evolving environmental regulations but also provide firefighters with high-performance solutions for suppressing flammable liquid fires. When choosing a Class B foam, look for options that have been certified to meet the stringent requirements of Underwriters Laboratories (UL), Factory Mutual (FM), LASTFIRE, GreenScreen®, and the International Civil Aviation Organization (ICAO).
Understanding the unique benefits of Class A and Class B foams is the first step, but proper training ensures these powerful tools are used effectively in the field. That’s where Perimeter Solutions’ ‘Know Your Foam’ program comes in.
Know Your Foam
Available at no cost to fire departments and other fire management agencies across the U.S. and Canada, the Know Your Foam program is a three-hour session that includes in-class training and outside hands-on application of Class A and Class B foam.
Attendees at these sessions learn the difference between Class A and Class B foams, fluorine-free Class B foams, as well as emulsifiers and water. Instructors demonstrate application techniques, including Roll On, Horizontal Spray, Bounce Off, Application then Reposition, Stitching, and Tend the Blanket.
The session also covers the different types of foam systems, how to use a foam injection system, and in-house maintenance of foam application products. In the hands-on portion, participants will use a manual inductor, nozzles, foam tubes, and foam injection systems.
Anyone interested in scheduling a Know Your Foam session for their department, multiple departments, or county-wide training can email [email protected]. We will need a fire engine with a foam injection system to conduct the training at your facility, along with a water source and a place where we can spray Class A foam.
By mastering foam application through proper training, firefighters can enhance their readiness and effectiveness, ensuring they’re equipped to handle evolving fire threats.
About the Authors
Norbe Puroll leads Business Development, Government and Municipal at Perimeter Solutions. He has worked in fire safety for 36 years, 18 as a Volunteer Firefighter/EMT. Prior to joining Perimeter Solutions, Puroll sold fire apparatus and equipment for 28 years. He can be reached at [email protected].
Mark Siem is Business Development Manager at Perimeter Solutions. He has worked in Research & Development in the fire safety industry for 17 years. Mark started his career in a hands-on role as a Chemical Technician fighting fires and working in the lab, before advancing to lead Class B firefighting activities.
