Experimental study of thermal stability and spread characteristics of gel-protein foam for liquid tank fires

Gel foams have been increasingly used for extinguishing coal fires due to its high thermal stability. However, their applications in liquid fuel fires are very limited because of its high viscosity. In this work, the thermal stability and spread performance of -gel-protein foams were examined for tanks fires against a commercial fluorinated foam (FF). Fourier transform infrared spectra (FTIR) and scanning electron microscopy (SEM) of the gel-protein foams were analyzed to unravel its gelling mechanism. The extinguishing mechanism of the foams was also investigated. The results showed that the gel-protein foam attached by a dense gel film layer, formed by –COO- and Ca2+, can efficiently improve its foam stability. The gel-protein foam also showed good thermal stability with a collapse time of more than 1800 s, a 50% increase over FF. and a water loss temperature of 156 °C, 15 °C higher than that of FF. The gel-protein foam also demonstrated excellent firefighting efficiency in the gasoline tank fire extinguishing tests with a faster spreading rate compared with FF due to the formation of the 'egg-box' gel structure by calcium alginate.