A comparison of experimental methods to determine the minimum explosible concentration of dusts

An experimental investigation of dust explosions was conducted using a 20 L Siwek explosion chamber, to examine test methods for determination of the minimum explosible concentration (MEC) of combustible dusts. Two methods, one proposed by the American Society for Testing and Materials (ASTM) and the other by the International Electrotechnical Commission (IEC), were compared. The MECs of gilsonite, Pittsburgh coal, oil shale and Pocahontas coal dusts were determined in the 20 L chamber. The test results were interpreted according to the ASTM criterion and the IEC criterion and compared with data available for the four dusts from the US Bureau of Mines 20 L chamber and large-scale testing (1 m(3) chamber and mine-scale). MEC values obtained from the IEC test method were generally lower than the values from the ASTM test method. The primary reason for this is the difference in recommended ignition energy between the two methods. Also, an ignition energy of 2500 J was most suitable for determination of minimum explosible concentrations for most of the dusts studied in the 20 L Siwek chamber. This ignition energy gave values that were comparable with data from large-scale experiments. Copyright (C) 1996 Elsevier Science Ltd.