What type of foam is commonly used for suppressing flammable liquids?

Aqueous Film Forming Foam (AFFF) is specifically designed for suppressing flammable liquids, such as petroleum-based fuels. Its unique composition allows it to form a film on the surface of the liquid, which effectively seals off the fuel from oxygen and reduces the release of flammable vapors. This film also aids in the rapid application and spreading of the foam over the flammable liquid, enhancing its extinguishing capabilities.

While protein foam and alcohol-resistant foam serve important roles in different fire scenarios, AFFF is the most commonly used foam in firefighting situations involving flammable liquids, particularly in industrial and aviation contexts. Class A foam, on the other hand, is primarily effective for ordinary combustibles like wood and paper, making it less suitable for flammable liquids. Thus, AFFF is the preferred choice in situations where flammable liquid fires are a concern due to its enhanced performance characteristics tailored for those types of incidents.