What type of fire typically requires a foam-based suppression method?

Foam-based fire suppression methods are primarily effective for Class B fires, which involve flammable liquids such as gasoline, oil, and solvents. Foam works by creating a blanket over the burning material, cutting off the fire's oxygen supply and preventing vapors from igniting. This is critical because flammable liquids can spread rapidly and can reignite if not properly smothered.

In contrast, Class A fires involve ordinary combustibles like wood, paper, or cloth, which are more effectively extinguished using water or other Class A fire extinguishing agents. Electrical fires require agents that do not conduct electricity, such as carbon dioxide or dry chemical extinguishers, to avoid the risk of shock or further ignition. Combustible metal fires require specialized extinguishing methods, such as dry powder agents, as standard foam or water can react dangerously with the burning metals. Thus, Class B fires are the specific type that necessitate foam suppression techniques for effective control and extinguishment.