Electrostatic dust explosion hazards – towards a <1 mJ synchronized-spark generator for determination of MIEs of ignition sensitive transient dust clouds

•Some industrial dusts have MIEs in air significantly lower than 1 mJ.•Current standard MIE tests have a lower spark energy limit of 1–3 mJ.•Synchronization methods that works for spark energies >1 mJ is needed.•The present paper describes such a method.•MIE for propane/air using this method compares favourably with recent published values.

In current standard MIE tests for dusts various methods are proposed for synchronizing the electric spark with the transient dust cloud, but they all have a lower spark energy limit of 1–3 mJ. Some industrial dusts have MIEs in air significantly lower than 1 mJ. There is a need, therefore, for a synchronization method that works below 1 mJ. The present paper describes an improved version of the synchronized-spark generator developed by Randeberg et al. [25]. Adequate performance of the improved generator is indicated by a comparison of the MIE obtained for propane/air with values published by other workers.