Which type of foam is specifically designed for hydrocarbon fires?

Aqueous Film-Forming Foam (AFFF) is specifically formulated to combat hydrocarbon fires, such as those involving fuels like gasoline, oil, and other petroleum products. The primary function of AFFF is to create a film that separates the fuel from the air, effectively cutting off the oxygen supply and suppressing the flames. When applied to a hydrocarbon fire, AFFF spreads rapidly over the surface of the burning liquid, forming a protective blanket that not only extinguishes the fire but also prevents re-ignition by sealing the vapors.

The design of AFFF includes surfactants that reduce the surface tension of water, allowing it to spread more easily over burning fuel. This unique characteristic is what makes AFFF more effective than other types of foam in managing hydrocarbon fires. In contrast, the other foam types, such as protein foam and fluoroprotein foam, while useful for certain applications, are not specifically optimized for hydrocarbon fuels and may not provide the same level of efficacy in extinguishing fires involving these substances. Class A foam is primarily used for fires involving ordinary combustibles like wood and paper, and would not be effective against hydrocarbon fires.