1.1 This test method determines the minimum ignition energy of a dust cloud in air by a high voltage spark. This test method is intended to develop data to be used in deciding whether or not combustible dust-air mixtures are considered to be ignitable with respect to electrical discharge. Ignition energies determined by this method would be compared with ignition energies of other dusts to assess the relative hazard with regard to ignition by a pointed source, for example, electrostatic discharges, sparks from electrical equipment, friction sparks. Data obtained from this test method provide a relative data of ignition sensitivity of a dust cloud. Appendix X2 of this test method includes guidance on the significance of minimum ignition energy with respect to electrostatic discharges.