Filter cake thickness detector

Claim 1

APPARATUS FOR DETECTING THE THICKNESS OF A FILTER CAKE DEPOSITED ON A FILTER ELEMENT IN A FILTER TANK, COMPRISING A TUBULAR MEMBER SURROUNDING AN OPENING IN THE WALL OF SAID TANK DIRECTLY OPPOSITE SAID FILTER ELEMENT, A HOUSING MOUNTED IN SAID TUBULAR MEMBER, SAID TUBULAR MEMBER HAVING AN INTERNAL SIZE SUBSTANTIALLY LARGER THAN THE EXTERNAL SIZE OF SAID HOUSING, SAID HOUSING BEING ENTIRELY DISPOSED WITHIN SAID TUBULAR MEMBER IN DIRECT COMMUNICATION WITH A FILTER CHAMBER PROVIDED IN SAID TANK A FLEXIBLE DIAPHRAGM DISPOSED IN SAID HOUSING, SAID DIAPHRAGM HAVING THE PERIPHERY THEREOF FIXEDLY SECURED AND SEALED TO SAID HOUSING FOR SEPARATING SAID HOUSING INTO FIRST AND SECOND PRESSURIZABLE COMPARTMENTS, AN OPENENDED CONDUIT SUPPORTED BY SAID HOUSING AND EXTENDING FROM SAID TUBULAR MEMBER INTO SAID TANK, SAID CONDUIT OPENING AT ONE END INTO SAID SECOND COMPARTMENT AND AT THE OTHER END INTO SAID FILTER CHAMBER AT A LOCATION IN PROXIMITY TO A LOCATION ON SAID FILTER ELEMENT AT WHICH SAID FILTER CAKE BUILDS UP WHEREBY DURING OPERATION OF SAID FILTER SAID CAKE GRADUALLY CLOSES OVER SAID OTHER