How are metal/Class D fires controlled?

• A. Use dry powder or dirt; avoid breaking the protective crust because doing so can cause flashback
• B. Use water to cool the surface first
• C. Apply foam directly to the burn without any crust protection
• D. Use Halon while removing the crust gradually

Answer: (A)

When dealing with metal fires, the priority is to smother the burning metal and remove its access to air, while keeping the hot surface insulated. Dry extinguishing powders designed for metal fires, or clean dry dirt/sand, are used to blanket the metal so the flame can’t get oxygen and the heat is absorbed, slowing or stopping the chemical reaction. Keeping the protective crust intact is important because it helps limit oxygen contact and stabilizes the hot metal surface; breaking that crust can expose fresh metal that may reignite and even cause a rapid flare or flashback. Water and foam react violently with many burning metals, spreading the fire or causing explosions, and Halon isn’t effective for metal fires.