Method of cleaning plate-type filter elements located in a tank filter

Claim 1

Method of cleaning plate-type filter elements in a tank filter where the tank filter comprises an upper chamber for filtrate, a lower chamber for unfiltered liquid, a sheet separating the upper chamber from the lower chamber and a plurality of plate-type filter elements depending downwardly from the upper chamber through the sheet into the lower chamber with the filter elements made up of a plurality of discs stacked one on top of the other and forming microfine slots therebetween when the discs are pressed together, wherein the method comprises the steps of placing a tubular member around and laterally enclosing at least an axially extending portion of a plate-type element from the end of the element spaced downwardly from the sheet and forming an annular chamber about the exterior of the element with the inner surface of the annular chamber being defined by the exterior surface of the plate-type element and the outer surface being defined by the inner surface of the tubular member, sealing the upper end of the annular chamber between the exterior surface of the filter element and the laterally enclosing tubular member, and introducing a pressurized cleaning fluid directly into the lower end of the annular chamber for providing a body of the pressurized cleaning fluid in the annular chamber for flow directly inwardly from the annular chamber over the full annular and axial extent of the element within the laterally enclosed chamber so that the full pressure of the pressurized cleaning fluid within the annular chamber acts over the entire surface of the laterally enclosed portion of the element with the pressurized cleaning fluid flowing inwardly between the plates of the filter element in the same direction as normal filtering flow for dislodging any contamination between the plates.