Which type of foam is typically used for suppressing class B fires?

Aqueous film-forming foam (AFFF) is specifically designed to suppress Class B fires, which involve flammable liquids such as gasoline, oil, and solvents. The distinguishing feature of AFFF is its ability to form a thin film that helps to smother the fire, separating the fuel from the oxygen and cooling the flame. This film also spreads quickly across the surface of the liquid, effectively preventing re-ignition and allowing for effective suppression of volatile fuels.

The chemical composition of AFFF allows it to work effectively on a wide range of hydrocarbon and polar solvent fuels, making it versatile and widely used in firefighting scenarios involving flammable liquids. Its effectiveness in controlling vapors and reducing the heat produced by the fire further emphasizes its superiority in Class B fire situations.

In contrast, while each of the alternative foam types mentioned can have uses in fire suppression, they are not as universally effective for Class B fires as AFFF. Protein foam primarily targets Class B fires but may not spread as effectively as AFFF. Alcohol-resistant foam is better suited for polar solvent fires but is not typically the first choice for general Class B fires. Water-soluble foam, while useful in certain scenarios, does not provide the same level of efficiency and protection from