Disc filter having means for sensing the thickness of filter cakes and

Abstract

A disc filter includes a housing and a plurality of filter discs mounted in the housing at different levels of the latter. Means is provided for sensing the presence of a filter cake formed on one of the filter discs when the filter cake has a predetermined thickness. The sensing means includes a sensing member which is displaceable in response to the generation of a pressure differential thereacross. The sensing means further includes a switch which is connected with the sensing member and is operative in response to displacement of the sensing member. The sensing member, which is favorably in the form of a plate, is located intermediate a pair of the filter discs and is preferably arranged immediately below the lower surface of the upper filter disc of the pair. In operation, a medium to be filtered is admitted into the housing of the filter under pressure. As the medium is filtered by the filter discs, filter cakes build up on the filter discs. When the filter cake formed on the filter disc located immediately below the sensing member reaches the level of the sensing member, a pressure differential caused by the pressure of the medium being filtered is created across the sensing member. As a result, the sensing member is displaced and a signal is generated. The signal may be used to terminate the filtering operation so that the thicknesses of the filter cakes do not become excessive.