A Class D fire involves which type of material?

• A. Flammable liquids
• B. Combustible metals
• C. Gases
• D. Ordinary combustibles

Answer: (B)

Fires involving combustible metals are handled as a distinct class because these metals burn differently from other common materials. Combustible metals such as magnesium, titanium, sodium, potassium, and aluminum can reach extremely high temperatures and may react violently with water or some other extinguishing media. Because of these unique properties, they require specialized extinguishing agents—dry powders designed for metal fires—that create a barrier between the metal and air and help absorb heat. Using water or ordinary extinguishing media can worsen the reaction or cause dangerous explosions, so metal fires aren’t treated like fires of ordinary combustibles or flammable liquids. This is why the material described is combustible metals.