A Comparison of Water Additives for Mopping-up After Forest Fires

Abstract

A trial was carried out to compare the effectiveness of six extinguishants currently used in forest fire mopping up operations by the Western Australian Department of Conservation and Land Management. The extinguishants; water alone, water with retardant, foam, retardant plus foam, wetting agent and retardant plus wetting agent were compared by applying them to burning heaps of dry pine logs. There were twelve replicates of each extinguishant treatment, with one of each type being applied each day over twelve days. Foam, used alone or with retardant, was most effective in extinguishing flaming combustion, both in terms of the time taken and the amount of water used, but was least effective in preventing the re-ignition of hot, smouldering logs. Retardant plus foam required significantly less total water than the other extinguishants because of the effect of the retardant in delaying re-ignition. In terms of total water used the most expensive treatment was straight water, requiring 17% more than retardant plus foam but only about 7% more than the other four treatments. The poor performance of the foam treatments in preventing re-ignitions, may have been due to the method of application. The observed advantage of foam in terms of knockdown capability needs further validation.