Abstract: The regulations and requirements of EN14034-3:2006^\[1\], E1515^\[2\] and GB/T 16425—1996^\[3\] for the measurement methods of lower explosive limit concentration of dust cloud differ from each other. To more precisely research the lower explosive limit of dust cloud, the lower explosive limit of niacin dust with particle size of 96~113 μm is test in 20 L spherical explosion test apparatus according to statistical data collection. Based on logistic regression model, the test results are analyzed using SPSS statistical software to obtain the probability distributions for ignition versus dust concentrations of niacin dust. The scope of dust cloud explosion limit proposed in GB/T 16425—1996 dust cloud explosion limit concentration measurement method is quantified, the influences of different experimental times on the lower explosive limit probability distribution are analyzed. The analysis result shows that the range of the confidence interval is the narrowest with the lower explosive limit of the particularity of 50%. For different number of experiments, the trends of the lower explosive limit probability on both sides of the value are different. Compared with the results obtained by other dust cloud explosion limit concentration measurement methods, the lower explosive limit of niacin dust which is expressed in the probability is more in line with the actual situation.

Key words: explosion mechanics, probabilistic and statistical analyses, nicotinic acid dust, lower explosive limit, logistic regression model