Triboelectrostatic Phenomena in Suction-type Dilute-phase Pneumatic Transport Systems

Pulverulent and granular materials processed in any suction-type dilute-phase pneumatic transport system tribocharge the pipes they move through. The aim of this study is to refine the understanding of the triboelectrostatic phenomena involved. A laboratory installation was employed for the investigation of the charging and discharging of various zones of an insulating pipe during and after the suction of a well-defined quantity of fine, dust-like, particles. The amount and the sign of the charge that was measured using several custom-designed electrostatic induction probes depended on the nature of the processed powders and varied from one zone of the pipe to another. Surface potential decay measurements confirmed that the insulating pipe retains high levels of charge for several hours after the cease of the suction. These observations point out the need of thorough laboratory modelling of any new pneumatic transport system, in order to avoid the electrostatic hazards related to electric charge build-up in various parts of the installation during operation.