CFD pump foam should be used at what percent concentration for all flammable liquids fires?

• A. 1%
• B. 2%
• C. 3%
• D. 5%

Answer: (C)

Foam protects the fire by forming a stable blanket on the liquid surface, cooling the fuel, and separating it from air to prevent reignition. For most hydrocarbon flammable-liquid fires, a three percent foam solution provides the right balance: it blankets quickly, maintains an effective film, and drains well enough to keep the foam usable and controllable with standard equipment. If you used a much lower concentration, the foam might be weak and fail to cover the surface adequately, allowing vapors to continue burning. If you used a much higher concentration, the foam can become overly thick and slow to discharge, wasting concentrate and sometimes reducing the effectiveness of the application. While polar solvents may require different, often higher, concentrations, the typical, widely recommended approach for common flammable liquids is three percent.