A COMPLETE ELECTRODYNAMIC MODEL FOR FILTER INDUCED ELECTROSTATIC DISCHARGE - PART 1 QUALITATIVE MODEL
When non-aqueous liquids flow through filter media both filters and
liquids become electrical charged. If charging is sufficient electrostatic
discharges (ESD) may occur: (a) within the filter medium, (b) between
filter element and housing, (c) between filter housing and external
metal surfaces, (d) from downstream surfaces. ESD is associated with
ruined filters, damaged metal parts, explosions, and lubricant
breakdown including formation of varnish precursors in turbine oils.
Filter induced ESD has been studied for more than 50 years. However,
these studies of particular fluids and filters led to recommendations for
mitigating ESD with limited utility. To remedy this situation a program
has been initiated linking underlying mechanisms with experimental
and field data, resulting in guidelines for preventing ESD in a wide
variety of applications. This first paper summarizes key findings,
presents previously unpublished data, and outlines the mechanisms
generating ESD in filtered systems.