LABORATORY STANDARD TECHNIQUE FOR INSULATING PROPERTIES OF FOAM ON HEPTANE SURFACE

The current research demonstrates that when highly-inflammable liquids are extinguished with foams, the cardinal mechanism of extinguishing effect lies in ability of foams to reduce dramatically the flow rate of fuel into the zone where vapour-air mixture emerges. It also shows that the flow rate of fuel depends on mutual wetting of fuel and foam in the boundary layer of foam bubbles and is determined by the structure of the boundary layer which emerges when the foam contacts hydrocarbon. There are given the research findings of surface activity of foam-and-water solution on the border with heptane, and mutual spreading curves on the basis of these measurements. There is suggested a laboratory standard technique for insulating properties of low expansion foam. This technique requires a subsurface extinguishing efficiency tester of foam to be used while the foam is being introduced to the bottom of a container with heptane. Here it is also shown that ignition time of heptane from beneath a foam layer is closely bound to a ratio of spreading rates of the solution and heptane.