Wash filter element

Claim 1

A CYLINDRICAL WASH FILTER ELEMENT FOR HIGH FLOW RATE FLUID FILTRATION HAVING EFFICIENT WASH FLOW ACTION TO MINIMIZE PLUGGING, COMPRISING AN OUTER FLOW CONTROL CYLINDER OF PERFORATED SHEET METAL ENCLOSING A SMOOTH-SURFACED CONCENTRIC CYLINDRICAL FILTER COMPOSITE OF WIRE MESH BONDED TO A SINTER-BONDED WIRE MESH, A CONCENTRIC CYLINDRICAL FLOW-REDUCING INSERT MEMBER ENCLOSED BY THE FILTER, THE FILTER INNER WALL AND INSERT DEFINING THEREBETWEEN AN ANNULAR WASH FLOW PASSAGE HAVING A WIDTH RANGING FROM 360* TO A SEGMENT OF THE VOLUME ENCLOSED BY THE FILTER, AND VARIABLE IN VOLUME, BEING GREATEST IN VOLUME AT ITS INLET AND DIMINISHING UNIFORMLY IN VOLUME TO THE OUTLET, A CENTRAL PASSAGE IN THE INSERT MEMBER, A RELIEF VALVE DISPOSED ACROSS THE CENTRAL PASSAGE, AND ADAPTED TO OPEN AT A PREDETERMINED PRESSURE DIFFERENTIAL ACROSS SAID PASSAGE, INLET AND OUTLET PASSAGES COMMUNICATING WITH THE ENDS OF THE WASH FLOW PASSAGE AND THE CENTRAL PASSAGE, BOTH SAID PASSAGES BEING INTENDED FOR FLOW OF UNFILTERED FLUID, THE WASH FLOW PASSAGE BEING SO DIMENSIONED, AND THE FLOW CONTROL CYLINDER HAVING AN OPEN AREA SUCH THAT THE RATIO OF THE PRESSURE DIFFERENTIAL $P1 THROUGH THE FILTER ELEMENT TO THE PRESSURE DIFFERENTIAL $P2 ACROSS THE FILTER $P1:$P2 IS AT LEAST 2:1 AND THE REYNOLDS NUMBER IN THE WASH FLOW IS AT LEAST 5X10**3 AT A VELOCITY AT LEAST TEN TIMES GREATER THAN THE VELOCITY OF THE FILTRATE FLOW, AND THE RELIEF VALVE BEING ADAPTED TO MAINTAIN THE RATIO AT INPUT FLOW BEYOND A PREDETERMINED MINIMUM FLOW RATE.