Electrostatic hazards in powder handling operations

Abstract

Charge build-up is observed in most powder handling operations as soon as the powder is highly insulating or the equipment is made from highly insulating material. The ignition probability by discharges due to static electricity can drastically be reduce in practice, if only conductive material is used for all parts of the equipment and installations and if all these parts are safely earthed. The question remains, however, whether the charge retained on a highly insulating product in powder form will be able to ignite this powder, even if the powder is handled and processed in conductive and earthed equipment. Based on extensive research performed during the last decade in this field, ignition of highly insulating powder must be expected under certain circumstances (formation of so-called cone discharges), even if the powder is handled or processed in metallic and earthed equipment.