Aqueous Film Forming Foam (AFFF) extinguishers are primarily intended for which class of fire?

Aqueous Film Forming Foam (AFFF) extinguishers are specifically designed to combat Class B fires, which involve flammable liquids such as gasoline, oil, and other petroleum products. AFFF creates a film over the surface of the burning liquid, effectively sealing it off from the oxygen in the environment and suppressing the flames. The foam also helps to cool the area and prevent re-ignition, making it a highly effective tool for tackling these types of fires.

In contrast, Class D fires involve combustible metals, which require specialized extinguishing agents that can handle the unique chemical properties of these metals. Class K fires are related to cooking oils and greases, often found in commercial kitchen settings, and require agents specifically formulated for those substances. Class A fires involve ordinary combustibles like wood, paper, and textiles, which are more effectively tackled with water or foam types specifically designed for those materials. Thus, AFFF is not suitable for Class D, Class K, or Class A fires, making Class B the correct designation for this type of extinguisher.