What type of agents are Class A foams primarily made of?

Class A foams are specifically formulated using hydrocarbon-based surfactants that enhance their effectiveness when combating ordinary combustible materials, such as wood, paper, and textiles. These surfactants work by reducing the surface tension of water, allowing it to spread more easily and penetrate deeper into fuels, which increases the cooling and smothering effects of the foam.

Unlike alcohol-based agents, which are used primarily for Class B fires involving flammable liquids, Class A foams are designed to address a different class of fires. Furthermore, while water-based agents can also extinguish Class A fires, these are typically just water without the added benefits that surfactants provide. Organic solvents do not have the characteristics needed for effective fire suppression and may actually pose additional fire hazards when in contact with flammable materials.

Therefore, the use of hydrocarbon-based surfactants in Class A foams distinguishes them as effective tools for tackling fires fueled by common combustible materials, making this the correct choice.