Dependence of the volume stability on the expansion rate of low-expansion foam

In this work, we analyzed and summarized the results of experimental studies of the characteristics of air-mechanical foam generated on the deflector type sprinklers and in the foam generating devices with mesh using three brands of general purpose foam concentrates, one brand of special purpose foam concentrate and one brand of foam concentrate used to extinguish fires as a wetting agent. As a result of the analysis, a linear dependence of the volume stability on the expansion rate of the foam was established, and the influence of physical characteristics (wetting ability, surface tension and dynamic viscosity) and the jet speed of the foam concentrate solution on the proportionality coefficient of the established dependence was determined. This dependence relates the stability and expansion rate of foam not only when using deflector type sprinklers for automatic extinguishing systems, but also using nozzles of fire barrels and other foam-generating devices that allow the generation of low-expansion air-mechanical foam, and does not depend on the geometric dimensions of the devices used. The resulting equation makes it possible to determine the stability of foams using the value of their expansion rate. It will help to reduce the time and money spent on experimental determination of the foam stability.