Abstract: An electrostatic filter removes particles from non-electrically-conductive fluids. A pair of electrical conductors extend through a filter housing for providing one of a plurality of D.C. voltage levels selected to control electrical current consumption within the filter. A plurality of identical perforated, electrically conductive plates are connected to individual ones of the conductors by reversing the orientation of the plate. Successive plates are alternately positive or negative. Porous foam filter pads are located between each pair of plates. A permanent magnet is located in the foam pads which are between the positive to negative, but not between negative to positive, conductive plates, determined with respect to the direction of the fluid flow within the filter housing. The permanent magnetic field interacts with a corona formed around plates of one polarity in order to agitate the particles which then become entrapped within the porous foam filter pads.

Abstract: A fluid filter is designed primarily but not exclusively to filter spent fluids which may contain particulate contaminants. The filter has an assembly which may be slid into or out of a canister housing for manufacture, repair, or replacement. The assembly is a stack of porous filter media separated by perforated metal plates. The metal plates may be arranged in sets, comprising positive and negative electrostatic plates followed by magnetic plates. Or, the metal plates may be arranged in a sequence tailored for the electrical conductivity of a given fluid. A pair of rod electrodes are threaded through holes in the various plates and porous filter media. One rod electrode is connected to all positive plates. The other rod electrode is connected to all negative electrostatic plates.