Incendivity of electrostatic discharges in dust clouds: the minimum ignition energy problem

Assessmentofelectrostaticignitionriskinpowderhandlingplantsrequiresadecisionasto whetheradustcloudcanbeignitedbyspark,cone,corona,brushorpropagatingbrush discharges.Itisgenerallyacceptedthatcoronadischargesfromelectrostaticallycharged bodieswillnotignitedustclouds.Theenergiesofpropagatingbrushdischargescanbe severaljoulesandcanigniteawiderangeofdustclouds.Safetyisthereforeachievedby avoidingtheconditionsunderwhichsuchdischargeswouldoccurratherthanconsiderationof thesensitivityofthedustcloud.Theincendivityofsparkdischargesfromconductors(e.g. metalplant)isassessedbycomparingthetotalenergystoredontheconductorwiththe MinimumIgnitionEnergy(MIE)ofthedustcloud.EquivalentEnergy(Ref.1)hasbeenused toassesstheincendivityofbrushdischargesfromplasticmaterials(Ref.1)andofcone dischargesfrombulkpowder(Ref.2).ThisalsorequiresaknowledgeoftheMIEofthedust cloud.