Hazard assessment and effect of nano-sized oxidiser on sound level analysis of firecrackers

In this study, the authors synthesised nano-sized sulphur and oxidisers by the ball mill method and the size was detected using a particle size analyser. Pyrotechnic mixtures of compositions using five different oxidisers: potassium nitrate (KNO3), potassium perchlorate (KClO4), barium nitrate (Ba- (NO3)2), strontium nitrate (Sr(NO3)2) and bismuth oxide (Bi2O3), in different particle sizes, mixed with sulphur (S), aluminium (Al) and boric acid (H3BO3), were used to produce sound producing cakebomb firecrackers for analysis. A bulk density of 0.24-0.68 g cm-3 was maintained for homogeneity of the mixture. The sound level from newly formulated sound producing firecrackers (cake-bombs) showed a linear relationship with the weight of the mixture taken. Decreasing the particle size from micro to nano improves the efficiency of firecrackers using the oxidisers, KNO3, KClO4 but not for Ba(NO3)2, Sr(NO3)2, or Bi2O3. The analysis of safety characteristic data of thermal and mechanical sensitiveness indicates that the pyrotechnic mixture using the oxidiser KClO4 is highly sensitive to friction and impact. The limiting impact energy (LIE) of pyrotechnic compositions falls in the range of 2.55-4.51 J. LIE of nano materials was less compared to micro materials indicating that as the particle size decreases, the mixture is prone to hazards from impact. Thermal analysis indicates a high temperature for self propagating decomposition making the mixture thermally stable at room temperature.

Authors: Thanulingam, T. L.; Rajendran, A. Jeya; Karlmarx, P.; Subramanian, K.; Azhagurajan, A. ;Full Source: Journal of Pyrotechnics 2009, 28, 95-111 (Eng) ;