What type of fire could a fire extinguisher labeled with a Red square be used on?

A fire extinguisher labeled with a red square indicates that it is suitable for use on fires involving flammable liquids. This classification typically corresponds to Class B fires, which include fires involving substances such as gasoline, oil, or solvents. These types of fires require a specific approach to extinguishing, often utilizing foam or dry chemical agents, which are effective at smothering the flames and preventing reignition.

Understanding the classification helps in selecting the appropriate extinguisher for the specific type of fire encountered, as different materials combust in unique ways and require tailored methods for suppression.