Which class requires dry powder extinguishers?

Which class requires dry powder extinguishers?

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

Answer: (B)

Fire extinguishing agents are chosen by fire class. Metal fires require a dry powder extinguisher because water or other common agents can react violently with burning metals. The dry powder coats the metal and slows and interrupts the chemical reactions at the surface, effectively smothering the flame and preventing re‑ignition. This is why dry powder extinguishers are specified for fires involving combustible metals such as magnesium, titanium, and aluminum. Other fire types use different agents—for ordinary combustibles you’d use agents suited to wood/paper fuels, for electrical fires non‑conductive extinguishing media, and for flammable liquids a foam or dry chemical appropriate to those liquids.

Fire extinguishing agents are chosen by fire class. Metal fires require a dry powder extinguisher because water or other common agents can react violently with burning metals. The dry powder coats the metal and slows and interrupts the chemical reactions at the surface, effectively smothering the flame and preventing re‑ignition. This is why dry powder extinguishers are specified for fires involving combustible metals such as magnesium, titanium, and aluminum. Other fire types use different agents—for ordinary combustibles you’d use agents suited to wood/paper fuels, for electrical fires non‑conductive extinguishing media, and for flammable liquids a foam or dry chemical appropriate to those liquids.