Which statements describe typical foam concentration percentages for different fuels?

• A. Class B foams mix 1-6%; hydrocarbons 1% or 3%; polar solvents 3% or 5%.
• B. Class B foams mix 10-15%; hydrocarbons 8% or 12%; polar solvents 6% or 8%.
• C. Class B foams mix 0.1% or 0.5%; hydrocarbons 0.5% or 1%; polar solvents 1% or 2%.
• D. Class B foams mix 20%; hydrocarbons 15%; polar solvents 10%.

Answer: (A)

Foam concentration for Class B firefighting depends on the type of liquid fuel and the finished foam solution you apply. The typical overall mixing range for Class B foam concentrates is about 1 to 6 percent in the water to create the foam solution. Within that, hydrocarbon fuels are usually treated with the lower end, commonly around 1 percent or 3 percent. Polar solvents, which are more challenging to blanket and can re-ignite more easily, typically require higher concentrations, such as 3 percent or 5 percent. This balance ensures a stable foam blanket that cools, forms an effective film, and blankets the fuel surface without wasting concentrate. The other proposed ranges—like 10–15 percent, 0.1–0.5 percent, or 20 percent—do not reflect how Class B foams are normally applied and would be outside the standard performance specifications.