Dibromomethane as Promising Gaseous Fire Extinguishing Substance with Short Atmospheric Lifetime

Abstract

Calculation of dibromomethane atmospheric lifetime is carried out, as well as an experimental assessment of its fire extinguishing efficiency. Calculations show that methylene bromide atmospheric lifetime is 15.8 days so it rapidly decomposes in the troposphere. The main mechanisms of the removal of CH2Br2 from the atmosphere are its reaction with hydroxyl radicals and the processes of physical removal from the atmosphere. Special experimental equipment allowing to measure fire extinguishing concentration of gaseous fire suppressant having high boiling point is described. Experimentally measured minimum extinguishing concentration of methylene bromide for n-heptane is 2.5 % vol. According to this, CH2Br2 is close to the most effective gaseous fire extinguishing agents, such as C3F7I and C2F4Br2. LOAEL value for CH2Br2 is predicted at the level of 0.3-0.4 % vol. Due to the high boiling point of methylene bromide and its relatively high toxicity, the most appropriate way to use it in fire suppression is to create fire extinguishing mixtures, in particular, with fluorinated hydrocarbons. This approach allows to diminish application of greenhouse gases in fire protection and also to solve the problem of toxicity of extinguishing substance.

Characteristics of Impact on the Atmosphere of Perfluorisohexenes - Promising Components of Gas Extinguishing Compositions

“…It is also necessary to recognize that in spite of more than 30 years of the research in accordance with fundamental program [2] there are just few new agents appeared which are fully satisfied to the modern ecological demands (zero ODP, short atmospheric lifetime (less that 181 days) and low GWP) in addition to their relatively high extinguishing properties. Just fluorinated ketone FK 5-1-12 (C6F12O) [3], 2-bromo-3,3,3-trifluoropropene [4] and dibromomethane [5] can be mentioned.…”