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Measurement of Explosion Violence of Dust Clouds.
Proceedings of the International Symposium on the Explosion Hazard Classification of Vapors, Gases, and Dusts, National Materials Advisory Board, Publication NMAB-447 1987:181-204
Measurement of the explosive violence of dust clouds was discussed. Methods for preventing destructive overpressures in industrial equipment were described, including venting, automatic suppression, and isolation by high speed valves. Factors influencing the combustion rate of a dust cloud included the chemical composition of the dust and gas phase, initial temperature and pressure of the gas phase, particle size and shape distribution, degree of dispersion or aggregation of the particles, turbulence, and distribution of dust concentrations in the actual cloud. Volume scaling of explosion violence was discussed. It was noted that the cubic law for closed shell explosions is valid only for gases and dust clouds burning with thin flames, relative to vessel size, and which have identical velocities for any given combination of pressure and temperature in the unburned cloud ahead of the flame. Closed/bomb test apparatuses used for classifying the explosive violence of dust clouds were described. Realistic large scale vented dust explosion experiments conducted in a cyclone, a bag filter, and an elongated empty vessel and their correlation with data from conventional closed/bomb tests were discussed. These have shown that each closed/bomb experiment may provide a relevant simulation of the individual combustion rate for some situations; however, none of the test methods can reproduce the wide range of dust cloud combustion rates that occur in real situations. The relevance of the cubic law to practical situations was considered to be questionable. According to the author, dust classification methods should be validated by systematic full scale dust explosion experiments conducted in various types of process units.
Laboratory-testing; Industrial-safety; Dust-explosions; Explosive-atmospheres; Testing-equipment; Mathematical-models; Airborne-particles; Explosion-prevention;
Proceedings of the International Symposium on the Explosion Hazard Classification of Vapors, Gases, and Dusts, National Materials Advisory Board, Publication NMAB-447
Page last reviewed: September 2, 2020
Content source: National Institute for Occupational Safety and Health Education and Information Division