Fire Safety Science Digital Archive

This paper presents the experimental measurements to compare the vapour-suppression performance of recently developed synthetic foam formulations (that do not use fluorosurfactants) with that of an aqueous film forming foam (AFFF). A laboratory-scale method involving a flux chamber was deployed to create an environment that imitates the conditions of field tests. The method utilises a gas chromatograph to determine the breakthrough points of AFFF and synthetic-based foams. The measurements indicate that an AFFF formulation affords the best overall performance for the vapour suppression, with the longest times for breakthrough. The synthetic foams with no xanthan gum are characterised by almost-immediate break through time, while those incorporating xanthan gum achieve strong breakthrough resistance, delaying the onset of flammability conditions above the 2-cm foam blanket for 130 min. This performance can be compared with 159 min achieved by 1-cm blanket of AFFF formulation. Clearly, xanthan gum plays an important role in enhancing a mixture of synthetic hydrocarbon surfactants to achieve improved vapour suppression of water immiscible fuels.