Effect of temperature on stability and film thinning behavior of aqueous film forming foam

Abstract

In the extinguishing process, the stability of the foam extinguishing agent would be inevitably affected by the flame with high temperature, which has an impact on the effectiveness of the foam. Therefore, it is crucial to investigate the effect of temperature on the stability of foam. The prior research related with the foam stability has mainly concentrated on foam drainage and foam height. However, the details of foam stability have only been the subject of a few studies. In this paper, the effect of temperature on stability and film thinning behavior of aqueous film forming foam (AFFF) were studied using microscope and the optical interferometry device, where the bubble sizes, the film thinning rate and the film lifetime were measured and analysed. The results show that the foam stability and foam film stability were influenced by temperature significantly. The foam lifetime was discovered to decrease exponentially with the increase of temperature, showing that the foam became unstable under higher temperature. Besides, the predicted model of film thickness under different temperature was induced and verified, where the effect of temperature on the foam fluid viscosity was considered. It was also found that the film lifetime decreased exponentially with the increase of temperature, which was caused by the changing in the film surface adsorption, film surface elasticity and the film viscosity under higher temperature.