Toward Better Halon Substitutes: Theoretical and Experimental Studies on the Pyrolysis Mechanism and Fire-Suppressing Performance of C<sub>5</sub>F<sub>10</sub>O (Perfluoro-3-methyl-2-butanone)
Haijun Zhang, Xuefang Meng, Qi Yang, Xiaomeng Zhou
Abstract
The urgent desire for Halon substitution has propelled the exploration of potential alternatives because of the severe damage of Halon to the stratospheric ozone layer. As a perfluoroketone substance, C5F10O has a similar chemical structure and comparable environmental friendliness to that of the widely utilized Novec-1230 (C6F12O) extinguishant. Both theoretical calculations and experimental measurements are utilized to unveil the thermal decomposition and fire-extinguishing mechanisms of C5F10O in this study. It was found that the C5F10O pyrolysis generates perfluoroolefins, perfluoroalkanes, and highly active free radicals that can efficiently capture H· and OH· radicals in the flame to interrupt the chain reactions of combustion. Apart from the chemical exhaustion of radicals, the endothermic pyrolysis of C5F10O imposes a prominent cooling effect upon high-temperature fires. Moreover, the release of incombustible CO2 and perfluoroalkanes effectively dilutes the combustible fuel–air mixture in the combustion region. The synergistic chemical and physical suppression effects endow C5F10O with desirable fire-extinguishing effectiveness (6.83 and 6.04 vol % for suppressing methane-air and propane-air flames, respectively). Notably, compared with C6F12O, the less poisonous (CF3)2C═CF2 is emitted at high temperatures (700–800 °C) by C5F10O decomposition, indicating the biosafety of C5F10O in confined and human-exposed regions. These findings suggest the promising applicability of C5F10O in practical Halon replacement and the necessity of its further evaluation.