AFFF foam solutions are rated for application concentrations of which range?

Answer: C — 3% to 6%

AFFF foam performance depends on using the concentrate at the right dilution with water. The finished foam solution needs a certain amount of concentrate to form the film on hydrocarbon fuels and to create a stable foam blanket that both suppresses vapors and cools the fuel. The common rated application range for many AFFF products is 3% to 6%. At about 3%, the solution reliably forms the protective film and provides effective vapor suppression. Increasing to around 6% enhances the film and cooling for tougher fires or larger spills. Using much less than 3% often fails to produce a consistent film, while using more than 6% isn’t typically necessary for standard AFFF products and can waste concentrate or introduce other operational issues. So, the recommended and typical application concentrations fall in the 3% to 6% range.