Which extinguishing agent is versatile across Class A, B, and C fires?

Which extinguishing agent is versatile across Class A, B, and C fires?

• A. Water (Class A; cooling).
• B. Foam (Class B; smothering).
• C. Dry chemical powder (Class A/B/C; versatile).
• D. CO2 (Class B/C; displaces oxygen).

Answer: (C)

Extinguishing agents that work across multiple fire classes must interrupt the flame chemistry and prevent the fuel from continuing to react with the oxidizer. Dry chemical powder, especially the multi-purpose ABC type, does exactly that. It deposits fine particles that interrupt the reactions occurring in the flame and blankets the fuel surface to separate fuel from air, making it effective on Class A (ordinary combustibles), Class B (flammable liquids), and Class C (energized electrical) fires. Other agents tend to be strongest in one area—water cools for Class A, foam helps mainly with Class A and B, and CO2 displaces oxygen for B and C but does little for Class A. The powder’s broad effectiveness across A, B, and C is why it’s considered versatile for a universal extinguisher, though it does leave residue and requires cleanup after use.