Which type of extinguishing agent is suitable for Class A and B fires?

The suitable extinguishing agent for Class A and B fires is foam. Foam is particularly effective against Class A fires, which involve ordinary combustibles like wood, paper, and textiles, because it cools the burning material and creates a barrier between the fuel and the oxygen. Additionally, foam is effective for Class B fires, which involve flammable liquids such as gasoline and oil, as it forms a blanket over the liquid, smothering the flames and preventing the release of flammable vapors. This dual applicability makes foam a versatile option for combating both types of fires, ensuring control over the situation by addressing the unique characteristics of the fuels involved.

Water, while effective for Class A fires, is not suitable for Class B fires because it can spread flammable liquids and worsen the situation. Dry chemicals are also useful for a variety of fires, including Class B, but they do not provide the same cooling effect on Class A fires as foam does. Carbon dioxide is effective for Class B and some Class C fires but does not cool or suppress Class A fuel materials effectively, limiting its use in situations involving ordinary combustibles. Thus, foam stands out as the most compatible agent for both Class A and B fire scenarios.