Class B fires involve which types of materials?

• A. Wood
• B. Flammable liquids
• C. Metals
• D. Energized electrical equipment

Answer: (B)

Class B fires are defined by the type of fuel involved: flammable liquids. These include liquids like gasoline, solvents, oils, and greases that release flammable vapors capable of igniting. The distinguishing feature from other classes is that the fuel is a liquid (or a liquid-containing phase) rather than ordinary combustibles, metals, or energized electrical equipment. That’s why the best answer is flammable liquids—the category specifically targets fuels that are liquids and produce flammable vapors. In contrast, wood and paper fall under ordinary combustibles (Class A), energized electrical equipment falls under electrical fires (Class C), and certain metals burn under metal fires (Class D). For extinguishment, these fires require agents suitable for liquids (such as dry chemical, foam, or CO2) rather than techniques used for solids or electrical fires.