How should an aqueous film forming foam (AFFF) solution be applied onto a fuel?

When applying an aqueous film forming foam (AFFF) solution onto a fuel, the correct method is to rain it down gently onto the surface. This technique allows the foam to spread evenly over the fuel, creating an effective barrier that suppresses vapors and prevents ignition. The gentle application helps maintain the integrity of the foam, reducing the risk of it breaking apart before it fully covers the fuel.

This method is particularly effective in ensuring that the foam forms a film on the surface of the liquid, providing the best possible fire suppression. AFFF works by displacing air and smothering the flames, and a gentle rainfall application facilitates this process.

In contrast, applying the foam aggressively or splashing it could disturb the fuel and potentially cause flare-ups. Applying in a circular motion might not cover the surface evenly, and could lead to incomplete foam coverage, which limits the effectiveness of the foam in extinguishing the fire.