Water-based extinguishers are used to put out what class of fires?

• A. Class B
• B. Class A
• C. Class C
• D. Class D

Answer: (B)

Water extinguishers work by absorbing heat and lowering the fuel’s temperature below its ignition point. They’re most effective on fires involving ordinary combustibles like wood, paper, cloth, and similar solid fuels, which are classified as Class A. Using water on other fire types isn’t appropriate: on flammable liquids, water can spread the fuel and worsen the fire; on energized electrical equipment, water can conduct electricity and pose a shock risk; and on certain metal fires, water can react violently. So the best match for water-based extinguishers is Class A fires.