A model based on the perfectly stirred reactor (PSR) concept is used to correlate the minimum extinguishing concentration (MEC) of gaseous KOH, which was established in the cup-burner experiment. Both physical and chemical mechanisms of fire suppression are considered in PSR modeling. The combustion process of the CH4/air and gaseous KOH mixture contains a complex chain branch reaction. A high gaseous KOH concentration of type K agent in the methane flame results in strong flame inhibition. The influence of gaseous KOH on the combustion process involves capturing OH free radicals in the flames and reaching the inhibition effect by controlling key elementary reactions containing OH radicals in the combustion process. By calculation of the intermediate product production rate of the fire-extinguishing agent at a high temperature through the PSR model, the main paths of gaseous KOH inhibiting the methane combustion reaction can be obtained. An increased KOH concentration will not change the reaction mechanism.

Summary A novel hot aerosol extinguishing agent (HAEA), which is the combination of pyrotechnics and flame retardant technology, was found to have great efficiency in extinguishing Class B fires. A mixture of P and P3N5, referred to as P90x, was chosen as the reductant, and phase stabilized ammonium nitrate was chosen as the oxidant. This paper describes a study of the effectiveness of this agent in extinguishing n‐heptane fires (ie, Class B fires). We determined that the best efficiency was 15 g/m3 for extinguishing n‐heptane fires, four times more efficient than a traditional agent. The efficiency increases as the mass fraction of P90x rises. We also identified the key difference between the novel extinguishing agent and the traditional agent. The former consists of an inorganic phosphorus compound, while the latter is mainly comprised of KOH. Consequently, their extinguishing mechanisms are different. The phosphorus oxide of the novel HAEAs is the leading component to extinguish fire, which is more effective than alkali salts.

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Six types of gas generators based on guanidinium azotetrazolate (GZT) were designed into six formulations having different oxidants: GZT‐LiNO3 (1), GZT‐NaNO3 (2), GZT‐KNO3 (3), GZT‐Mg(NO3)2 (4), GZT‐Sr(NO3)2 (5) and GZT‐KMnO4 (6), respectively. The properties of these formulations were investigated in terms from gas production, appropriate combustion temperature and nontoxic gaseous emission. REAL software calculation program [1] was used to calculate the combustion heat at constant pressure, combustion heat at constant volume and specific volume in standard state. It showed that gas generators based on GZT with nitrate salts as oxidant exhibited better performance. Thus its thermal behavior and combustion temperature were studied further and the experimental results were consistent with the theoretical calculation results. Therefore, it can be concluded that formulation 3 has comprehensive optimal performance: low moisture content, insensitivity to friction, heightened vacuum stability, high combustion heat and specific volume. Namely, formulation 3 exhibited the most promising indications of commercial application, such as using in air bags of motor vehicles.

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