What class of fire extinguisher is effective on liquid fires?

The correct answer, Class B, refers to fire extinguishers that are specifically designed to combat fires involving flammable liquids such as gasoline, oil, and grease. These types of fires behave differently from those involving solid materials (Class A) or gases (Class C), which is why Class B extinguishers utilize substances like foam, CO2, or dry chemical agents to smother and cool the flames, effectively preventing re-ignition.

Class A extinguishers are aimed at ordinary combustibles, such as wood, paper, and cloth, while Class C is designated for electrical fires. Class D is intended for fires involving combustible metals, which often require specialized extinguishing agents due to the unique nature of the burning materials. Understanding these classifications is vital for effectively responding to different fire scenarios.