Which class of fires involves combustible metals such as magnesium or sodium?

Which class of fires involves combustible metals such as magnesium or sodium?

• A. A
• B. D
• C. B
• D. C

Answer: (B)

Fires are grouped by the type of fuel they burn. Combustible metals like magnesium or sodium behave very differently from ordinary combustibles, flammable liquids, or electrical equipment, so they’re placed in a separate category: Class D. This category covers metal fires and requires special extinguishing methods that interrupt the metal’s chemical reaction, not just cooling or smothering. Water should be avoided on metal fires because it can react with the metal and make the situation worse. Instead, use a Class D dry powder extinguisher or another approved metal-fire suppressant, or cover the metal with an inert material like sand to starve the reaction. In short, metal fires fall under Class D, which is why that choice is the best one.

Fires are grouped by the type of fuel they burn. Combustible metals like magnesium or sodium behave very differently from ordinary combustibles, flammable liquids, or electrical equipment, so they’re placed in a separate category: Class D. This category covers metal fires and requires special extinguishing methods that interrupt the metal’s chemical reaction, not just cooling or smothering. Water should be avoided on metal fires because it can react with the metal and make the situation worse. Instead, use a Class D dry powder extinguisher or another approved metal-fire suppressant, or cover the metal with an inert material like sand to starve the reaction. In short, metal fires fall under Class D, which is why that choice is the best one.