Mark Siem, Business Development-Industrial/Chemist at Perimeter Solutions, explores the role of Class A and Class B foams, their benefits and how training gaps have influenced their use 

Class A firefighting foam helps make firefighting more effective, improves its efficiency, and introduces other advantages to firefighters. Misconceptions about the technology and its capabilities, and lack of training have contributed to a decline in its use over recent years.

Now, as firefighters seek out new resources to enhance their firefighting efforts, many are reconsidering Class A foam.  

At the same time, advancements in Class B fluorine-free firefighting foams along with evolving regulatory requirements have led to a surge in interest in these solutions.  

The advantages of class a firefighting foam 

The primary advantage of Class A Foam is that it enhances water’s effectiveness in dousing flames. Water’s high surface tension causes it to bead up and roll off most fuels and away from heat too quickly to be able to absorb as much heat as possible.  

Class A foam contains hydrocarbon surfactants, and its addition to water reduces its surface tension, allowing for the solution to penetrate the fuel. When you add a small amount of foam concentrate to water, as low as 0.1%, the size of the water droplets shrinks, creating more surface area, resulting in better heat absorption. The water/foam solution also penetrates deep into Class A fuels (paper, wood, cloth, and some plastics) to stop flames. By increasing water’s effectiveness, foam allows firefighters to achieve more rapid fire suppression using less water—in fact it can increase water efficiency 2-4x.  

Use of foam also reduces the amount of water needed which makes it easier to preserve the scene for arson investigation, increases firefighter safety by shortening knockdown time, reduces the amount of toxins released in the air through combustion and decreases the likelihood of a fire rekindling. 

Dispelling misconceptions about class a foam 

Despite its demonstrable benefits, use of Class A foam has declined partially due to misperceptions. Some people mistakenly believe that Class A foam is fluorinated, but that is not the case. It has been tested and approved for wildland firefighting by the United States Forest Service (USFS), demonstrating its safety and effectiveness.  

An increasing gap in firefighter education has also contributed to the declining use of Class A foams. When Class A foam was initially introduced, fire departments provided extensive training to ensure that all firefighters were well-versed in its application and knew when and how to use it effectively.

Though the focus on education has declined, this is a great opportunity to refresh training efforts to ensure that firefighters are equipped to use foam effectively in their standard firefighting. 

Mark Siem

Many fire departments also perceive water as a free resource, leading to the assumption that adding a foam agent incurs unnecessary costs. In reality, the amount of foam required to create the optimal mixture is minimal—resulting in only a few cents per gallon.

The resulting water savings, additional wear and tear on trucks and fuel consumption, along with the enhanced firefighting capabilities foam provides, make it a cost-effective tool for protecting lives, property, and communities. 

Perimeter Solutions introduced its first Class A foam in the 1980s and today it offers two PHOS-CHEK^® options for firefighters: PHOS-CHEK^® WD-881 is one of the world’s most widely used Class A foams; and PHOS-CHEK^® First Response is a budget-friendly Class A foam concentrate that is effective on a wide range of applications. 

The advantages of Class B firefighting foam 

Class B firefighting foams are designed to combat flammable liquid fires involving gasoline, oil, and other hydrocarbon or polar solvent fuels. These foams form a blanket over the burning liquid, cutting off oxygen and preventing vapor release, which helps to suppress fires quickly and effectively. 

Environmental regulations have led to the introduction of new-generation fluorine-free foam alternatives.

Mark Siem

As Class B foam technology has improved, the U.S. Federal Aviation Administration (FAA) removed mandates requiring the use of fluorinated foams, and the U.S. military committed to phasing out their use in 2024 (except for shipboard applications). Organizations in the oil and gas industry are also actively transitioning to fluorine-free solutions. 

Perimeter Solutions offers a range of SFFF concentrates that meet regulatory environmental standards and deliver superior performance across the aviation, oil and gas, and other industries. Our portfolio includes: SOLBERG® VERSAGARD™ 1×3 AR-SFFF, SOLBERG® VERSAGARD™ 3×3 AS-100, SOLBERG® RE-HEALING™ 3×3 SP-100, and SOLBERG® 3% MIL-SPEC SFFF. 

Closing the knowledge gap with foam training 

Firefighting foam offers several key benefits, including enhanced firefighter safety and improved water efficiency, which reduces fire suppression times. To help address this, Perimeter Solutions offers multiple classes to train firefighters on the use of foam.  

The company’s Know Your Foam training program is available at no cost to fire departments and other fire management agencies across the U.S. and Canada. This three-hour session includes in-class training and outside hands-on application of Class A and Class B foam.

Participants learn the difference between these foams, as well as emulsifiers and water. Instructors demonstrate application techniques, including Roll On, Horizontal Spray, Bounce Off, Application then Reposition, Stitching, and Tending the Blanket.

The session also covers foam systems, foam injection systems, and maintenance of foam application equipment. During the hands-on portion, participants use manual inductors, nozzles, foam tubes, and foam injection systems. 

Perimeter also hosts training sessions to provide airport fire safety personnel instruction on the use of its SOLBERG^® 3% MIL-SPEC SFFF solution. The first fluorine-free foam concentrate added to the US Department of Defense Qualified Products List (QPL) and the first on the QPL to be GreenScreen Certified Silver^®, SOLBERG 3% MIL-SPEC is designed for fast knockdown and extinguishment of gasoline and Jet A fuel spill fires as identified in MIL-PRF-32725. 

The Perimeter Solutions Industrial Foam School was recently introduced and was designed specifically for industrial firefighters, hazmat teams, and municipal firefighters supporting industrial facilities. The first session will take place May 28-29, 2025, at the Delaware State Fire Academy in Dover, DE. Firefighters attending this course will learn everything they need to know about foam, application techniques for applying fluorine-free firefighting foam, and how to preplan for an incident using firefighting foam.   

Later Industrial Foam School sessions will be held October 9-10, 2025, at Lambton College in Sarnia, Ontario, Canada, and October 28-29, 2025, at The Fire Academy of the South in Jacksonville, Florida, with additional dates and locations to be announced.  

This article was originally published in the April 2025 Edition of International Fire & Safety Journal. To read your FREE copy, click here.