Parameters for assessing electrostatic risk from non-conductors - a discussion

Abstract

The incendivity of electrostatic discharge from non-conducting surfaces can be experimentally determined by passing such discharges through flammable atmospheres of varying ignition sensitivity. The interpretation of the significance of the data by the use of ignition probability levels 0.5 and 0.001 is discussed. It is concluded that the charge transferred in a discharge provides guidance on its incendivity but it is considered that this parameter should be used with caution in industrial situations. It is shown that flammable atmospheres with minimum ignition energies of 0.2 mJ and 0.04 mJ can be ignited by discharges from 10 cm 2 and 4 cm 2 areas of electrostatically charged polyethylene sheets and that plastic pipes of radius greater than 0.5 cm can ignite 0.2 mJ atmospheres.