Abstract: Intermittent explosion spray is a common problem when using dry powder fire extinguishing device. This problem is related to the formulation, uniformity and structure of the gas generating agent while the combustion stability is a direct manifestation of the combustion effect of the gas generating agent. In this paper, a kind of gas generating agent was prepared by mechanical mixing and freeze-drying, and the combustion stability of the gas generating agent is analyzed by high-speed camera. The scanning electron microscopy (SEM) was used to characterize the morphology of gas generating agent. The SEM images showed that the freeze-drying method was significantly better than mechanical mixing in the uniformity of samples. The combustion flame area is quantified by Matlab, and the results indicate that when comparing the ratio of the stable combustion time to the total combustion time, the average value of the mechanical mixing agent is only 13% while the freeze-drying agent reaches to 35.19%; when comparing the standard deviation of average flame area in the stable combustion stage, the mechanical mixing agent is 9.263 while the freeze-drying agent is 5.924.

Key words: gas generant; combustion stability; flame area;mixed medicine