Which concentration range describes Class A foam use for firefighting?

• A. 0.1-1%
• B. 0.5-2%
• C. 2-4%
• D. 5-10%

Answer: (A)

Class A foam is used as a wetting agent with water to help cooling and penetration of ordinary combustibles like wood and paper. Because the goal is to improve wetting and heat absorption without creating unnecessary buildup, the concentration is kept very low. The standard range for Class A foam is 0.1% to 1%, which provides effective wetting and cooling across various fire scenarios without the drawbacks of higher concentrations. The other ranges are either above what’s typical for Class A or belong to foam applications intended for different fuels, so they aren’t the standard choice for Class A firefighting.