The ABC’s of AFFF (Aqueous Film-Forming Foam)

Polyfluoroalkyl chemicals, or PFAS, make up AFFF foam. Resilient to heat, water, grease, and oil, PFAS compounds are a class of manmade chemicals. The Environmental Protection Agency (EPA) has designated them as a “forever chemical” since the chemical accumulates in people, animals, and the surroundings and breaks down somewhat slowly. It is also classified as a likely human carcinogen. A higher cancer risk has been linked to exposure to PFAS chemicals in firefighters, airport employees, military personnel, and any other occupation closely related to AFFF.

Laboratory AFFF proved to be rather successful in extinguishing liquid fuel flames because of its low viscosity and quick spreading capability when sprayed. For this reason, the US government increased the use of AFFF in the 1970s at Department of Defense sites and military facilities, including bases and installations. Soon after, airports and municipal fire departments all over the country started using AFFF. Comprising almost 75% of the market, the United States military now uses firefighting foams most extensively nowadays. Local fire departments and petroleum processing refineries account for the rest of the market.

On US Navy vessels and aircraft carriers, AFFF proved to be quite efficient as a firefighting agent because of its rapid coverage of the fuel and vapor release from the flammable liquid. AFFF proved quite successful in rapidly smothering fires caused by either a fuel liquid spill or a collision, so medical responders could rapidly treat the pilot(s).

The cooling and covering action of the film-forming foam stops heat and oxygen transfer. The blanket that the movie makes smothers the fire and traps the flammable vapors, breaking the chemical chain reaction. AFFF was quite successful in fire control and knockdown since it could spread rapidly across the liquid fuel. Sometimes the invisible film acting as a blanket over the combustible liquid causes a fire to be extinguished before the foam covers the liquid.

Still, over the past few years, some states have implemented legislation controlling the use of PFAS. States authorities in Maine, Minnesota, and Washington have been granted the power to forbid PFAS in diverse products. Twelve states—including California, Colorado, Connecticut, Hawaii, Illinois, Maine, Maryland, Minnesota, New Hampshire, New York, and Vermont—have already outlawed the sale of firefighting foam comprising PFAS.

If your state prohibits the sale of PFAS-containing firefighting foams, it may be necessary to replace current systems as they undergo hydrostatic testing. For more specifics, see Chapter 11 of NFPA 25. Existing AFFF systems must be replaced during hydrostatic testing due to restrictions on the sale of new AFFF foam in certain states.

If your state does not prohibit the sale of PFAS-containing firefighting foams, there is no need to replace existing installations as long as they are inspected, tested, and maintained according to manufacturer instructions and Chapter 11 of NFPA 25. Manufacturers of AFFF foam have halted production due to the upcoming phase-out and liability issues over AFFF and PFAS. In June 2023, 3M agreed to pay $10 billion in legal settlements over allegations that its firefighting foam contributed to PFAS contamination of drinking water. As many manufacturers no longer produce AFFF, it is likely that existing systems will need to be replaced owing to a lack of replacement components and equipment in the coming years. Existing installations will soon require hydrostatic testing, rendering it impossible to obtain new AFFF from manufacturers.

Several jurisdictions restrict PFAS chemicals used in firefighting and limit their outflow to prevent contamination of neighboring land. PFAS compounds have been identified in drinking water in the US.

Companies servicing existing AFFF systems must comply with NFPA 25’s mandate to conduct flow testing, especially since some states prohibit the use of AFFF foam outside of emergencies.

The International Fire Code (IFC) mandates foam systems to be inspected, tested, and maintained in line with NFPA 25.

The same freeze protection that AFFF foam offers is not offered by SFFF foam. Understanding the differences between SFFF and AFFF foams is crucial for fire prevention system designers and firefighters.

1. What do you want to protect?
2. Is existing equipment compatible with the new foam?

To decide on a course of action, both questions have to be addressed. Look at available foam formulations, considering expansion rate, drainage time, and cooling capacity.

For almost ten years, foam producers have been experimenting and creating alternatives for AFFF. One can find several non-fluorine foam products on the market. Industry evaluated new fluorine-free solutions and the US Department of Defense Fire Protection Research Foundation found they successfully extinguish liquid fuel fires. Manufacturer, fuel type, and discharge technique all affect the behavior of foam products free of fluorine. AFFF’s success stems from its capacity to create a film layer covering burning gasoline. Unlike AFFF, fluorine-free foams produce a bubble barrier that prevents fuel vapours from mixing with oxygen, so instead of leaving a film on the fuel they block. Thus, there isn’t a “one size fits all” fix for substituting AFFF. 

Contractors and public safety organizations face the challenge of appropriately disposing of AFFF after replacement. While some states provide free disposal of AFFF, it is typically limited to fire departments and other public safety agencies. Contractors should be prepared to handle disposal fees, which can reach $20 per gallon.

In summary, replacing old AFFF fire prevention systems has been a long-standing worry that is unlikely to be resolved soon.

Manufacturers have halted selling AFFF (or PFAS), making it challenging for enterprises to maintain these systems in the future months and years, even if their state has not established laws outlawing them. It’s inevitable that fire prevention specialists will need to consider when and how to replace current AFFF systems.