Fire Safety Science Digital Archive

The efficiencies of limestone and sodium chloride dusts in suppressing coal dust explosions have been measured in a large scale vertical explosion tube. The explosibility of the dust mixtures in small scale test apparatus hes been compared with their explosibility in the large scale tube. The results obtained with the coal dust/stone dust mixtures were in good agreement with those obtained from experiments elsewhere in a large scale gallery. The agreement indicated that the results obtained with other industrial dusts in the vertical tube would apply to larger scale industrial plant. The minimum percentages of the diluents required to prevent explosions in the vertical tube have been compared with those calculated from heat balance equations derived from a theory based on the thermal properties of the dusts. Reasonable agreement was obtained for limestone dust. Sodium chloride was a better explosion suppressor than stone dust and its efficiency was much greater then predicted by calculations based on its thermal properties.