Which agent is preferred for a fuel fire?

• A. Water
• B. Foam
• C. Dry chemical
• D. Dry powder

Answer: (B)

Foam is the agent of choice for fuel fires because it forms a stable foam blanket that floats on the fuel, cooling the liquid and, crucially, separating the fuel from the air. This film suppresses the vapors that feed hydrocarbon flames and helps prevent reignition after the flames are knocked down. Water alone can spread the fuel and doesn’t provide the vapor-suppressing barrier, so it’s less effective for large fuel pools. Dry chemical and dry powder can extinguish smaller fires, but they don’t deliver the long-lasting vapor suppression and surface blanket that foam provides, and residues can hinder aircraft operations.