Dry powder is used for which fires and what is its compatibility with other agents?

• A. Class C fires only; compatible with primary agents.
• B. Class A fires only; not compatible with primary or auxiliary agents.
• C. Class D/metal fires only; not compatible with primary or auxiliary agents.
• D. Gas fires only; compatible with all agents.

Answer: (C)

Dry powder extinguishing agents are specifically designed for metal fires (Class D). They work by coating the burning metal with a dry powder, which helps smother the fire, isolates the metal from air, and can form a crust that slows or stops the oxidation process. Because many metals react violently with water and other common extinguishing agents, dry powder is used on its own rather than mixed with water-based agents or foams. In practice, you apply the dry powder directly to the metal fire and avoid combining it with primary or auxiliary extinguishing agents, ensuring the powder remains effective and does not create hazardous reactions. This is why metal fires are described as requiring dry powder and not compatible with other extinguishing agents.