Which class of fire involves burning metals?

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

Answer: (C)

Fires are categorized by what is burning and how they’re fought; metal-burning fires fall under Class D. This category covers metals and metal powders such as magnesium, titanium, sodium, potassium, aluminum dust, and similar fuels. These fires behave differently from other types and often require specialized extinguishing agents—dry powders or other metal-specific smothering agents—because water or standard foams can react violently with reactive metals or fail to smother the heat source effectively. The other classes cover different fuels: ordinary combustibles like wood and paper, flammable liquids, or energized electrical equipment—none of which are metal fires.