Inhibitory effects of water mist containing alkali metal salts on hydrogen-natural gas diffusion flames

Fire extinguishing technologies of fine water mist containing additives have good application prospects. Additives that are efficient, nontoxic, nonpolluting, widely used, economical and reliable provide a reference for the application and promotion of fine water mist fire extinguishing systems containing alkali metal salts. In this paper, six potential alkali metal salt additives were selected: potassium carbonate (K2CO3), sodium carbonate (Na2CO3), potassium oxalate (K2C2O4H2O), potassium acetate (CH3COOK), potassium chloride (KCl), and potassium bicarbonate (KHCO3); these additives were delivered into the fires as mists of their solutions at certain concentrations, the extinguishing time was recorded, and the minimum fire extinguishing concentration (MEC) of fine water mist containing alkali metal salt was tested by using a cup burner experimental apparatus. In addition, different types of alkali metal salts were compared to determine the anions and cations with better fire suppression performance levels. The suppression efficiencies of different ratios of additive packages for hydrogen-doped natural gas diffusion flames were studied to determine a specific ratio of additive packages. Based on the results of the experiment, in contrast to the pure water mist, the suppression efficiency of alkali metal salt greatly improved. The cation extinguishing ability was K+>Na+, and CO32- and CH3COO- were better than other anions in alkali metal salts. An efficient compound additive was identified as 1.5% K2CO3 + 0.5% CH3COOK. With increasing hydrogen addition, the MEC of fine water mist with additives increased.