Fire Suppression
AFFF (aqueous film forming foams) were first developed by the U.S. Naval Research Laboratory in the early 1960's. Foam containing unique fluorocarbon surfactants covers a burning fuel pool and quenches the transport of fuel vapors to the flame above. Perfluorocarbon surfactants quickly block fuel vapors traveling through the foam, suppressing the fire. Perfluorocarbon surfactants have unique hydrophobic and oleophobic properties, but their use has been restricted due to harmful environmental and biological effects. Novel surfactants have been developed to replace perfluorocarbon surfactants, but none have met the fire extinction metrics set forth by U.S. MIL-PRF-24385. To better assess surfactants, evaluating fuel transport through the foam instead of suppression only may lead to a more quantitative ranking of surfactants that may be useful for fire suppression. Fuel transport through the foam is dependent on the foam thickness which can change due to foam degradation in a fire environment. Measuring transient fuel transport at room temperature cannot account for the rapid foam degradation that may occur due to the presence of hot fuel and the radiative fire above. We propose an optical diagnostic technique that will measure a foam’s effective fuel transport in a fire. A laser measuring CO2 absorbance will be directed above a fire. As the fuel burns, CO2 is generated. Foam will then be applied to the flame surface and the CO2 concentration will decrease as the foam blocks the transport of fuel vapors, decreasing the amount of fuel burning.
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