What type of extinguishing agent is typically used in a Class B fire?

Foam or dry chemical agents are the most effective for Class B fires, which involve flammable liquids such as gasoline, oil, or paints. These extinguishing agents work by smothering the fuel and preventing the vapors from igniting, while also cooling the burning liquid to inhibit further combustion.

Foam creates a barrier over the liquid surface, which helps to cut off the oxygen supply and suppress the flames. Dry chemical agents, such as those containing monoammonium phosphate or sodium bicarbonate, interrupt the chemical reaction taking place in the fire by forming a cloud of particles that disrupts combustion.

Water or steam is not suitable for Class B fires, as it can spread the burning liquid and exacerbate the situation. CO2 can be effective for extinguishing fires involving both solids and liquids, but it may not be as efficient as foam or dry chemicals when dealing with large quantities of flammable liquids. Wet chemicals are designed primarily for Class K fires, involving cooking oils and fats.

Overall, foam and dry chemical agents are specifically formulated to address the hazards presented by Class B fires, making them the correct choice.