Class B extinguishers are used for which fires?

• A. Flammable liquids and gas
• B. Electrical
• C. Combustibles
• D. Metals

Answer: (A)

Fires involving flammable liquids or vapors require a method that blocks the fuel from the air and cools the surface. Class B extinguishers are designed for this exact scenario. They deploy agents such as dry chemical powders, foam, or carbon dioxide that blanket the liquid and interrupt the flame, either by smothering the fuel source or by cooling the surface so the liquid can no longer reach its ignition temperature. Water is avoided on these fires because it can spread the flammable liquid, spread vapors, and make the fire worse. Other fire types—like electrical, ordinary combustibles, or metals—need different extinguishing approaches, so this class is specifically for fires involving flammable liquids and gases.