What type of fire extinguisher is suitable for Class B fires?

Dry chemical extinguishers are highly effective on Class B fires, which involve flammable liquids such as gasoline, oil, grease, and solvents. These extinguishers typically use a dry chemical agent, such as monoammonium phosphate, which works by interrupting the chemical reaction of the fire; this agent smothers the flames and prevents re-ignition by forming a barrier between the fuel and the fire.

In contrast, other options are not suitable for Class B fires. Water extinguishers, for example, can be dangerous when used on flammable liquid fires because water may spread the burning liquid, worsening the fire. Foam extinguishers can be used on Class B fires as well, but they are less common and effective compared to dry chemical options. Dust extinguishers are primarily designed for certain types of combustible metals and are not applicable for flammable liquids. Therefore, the dry chemical extinguisher is the most reliable choice for effectively combating Class B fires.