Pressure filter and filter tube therefor

Claim 1

A PRESSURE FILTER COMPRISING A TANK HAVING A CHAMBER FOR THE LIQUID TO BE FILTERED, AN INLET FOR SUPPLYING TO SAID CHAMBER UNDER PRESSURE A MIXTURE OF SAID LIQUID AND SOLID PARTICLES IN SUSPENSION, AN OUTLET FOR TH FILTRTAE FROM SAID CHAMBER, AND A FILTER UNIT MOUNTED IN SAID CHAMBER INCLUDING AT LEAST ONE FILTER TUBE HAVING A WALL APPROXIMATELY CIRCULAR IN TRANSVERSE CROSS-SECTION WITH A PREDETERMINED NORMAL DIAMETER COMPRISING A PLURALITY OF INTERLACED HELICALLY DISPOSED NON-STRETCHABLE AND NONCONTRACTIBLE BUT FLEXIBLE WIRES PROVIDING BETWEEN THEM FILTERING PORES THROUGH WHICH SAID LIQUID MUST FLOW FROM SAID INLET AT ONE SIDE OF SAID WALL TO SAID OUTLET AT THE OTHER SIDE OF SAID WALL UPON PRODUCTION OF A PRESSURE DIFFERENTIAL IN THE LIQUID AT OPPOSITE SIDES OF SAID WALL AND DURING SAID FLOW DEPOSITS SOLID PARTICLES IN SAID PORES AND IN A LAYER ON THE TUBE WALL, CERTAIN OF SAID WIRES RUNNING HELICALLY OF THE TUBE SIDE BY SIDE IN ONE DIRECTION AND OTHER WIRES RUNNING HELICALLY OF THE TUBE SIDE BY SIDE IN ANOTHER DIRECTION WITH THE HELICES DISPOSED AT ANGLES TO A PLANE PERPENDICULAR TO THE AXIS OF THE TUBE OTHER THAN THE NEUTRALITY ANGLE, THE FIRST-MENTIONED WIRES CROSSING AND EXTENDING UNDER SOME AND OVER OTHERS OF THE SECOND-MENTIONED WIRES, WHEREBY SAID WIRES ARE MOVABLE RELATIVELY TO EACH OTHER BOTH LONGITUDINALLY AND PERIMETERALLY OF THE TUBE TO EXPAND AND CONTRACT THE TUBE WALL IN DIAMETER AND LENGTH AND AT THE SAME TIME MAINTAIN SAID WALL OF THE SAME CROSS-SECTIONAL SHAPE IN RESPONSE TO VARIATIONS IN SAID PRESSURE DIFFERENTIAL AND THEREBY DISLODGE SAID LAYER OF SOLID PARTICLES FROM SAID PORES AND SAID WALL, AND A MEMBER LOOSELY MOUNTED WITHIN SAID TUBE WHOSE PERIPHERAL SURFACE IS NORMALLY SPACED FROM BUT IS ABUTTED BY SAID WALL AND THEREBY LIMITS INWARD MOVEMENT OR COMPRESSIBILITY OF THE WALL UNDER SAID PRESSURE DIFFERENTIAL AND HAS PASSAGES FOR FLOW OF LIQUID THROUGH THE TUBE, AT LEAST ONE END OF THE TUBE WALL BEING OPEN AND THERE BEING MEANS MOUNTING SAID TUBE IN THE TANK FOR FREE FLOW OF THE LIQUID THROUGH SAID OPEN END TO AND FORM SAID OUTLET AND THE OTHER END OF THE TUBE BEING FORMED TO PROVIDE FOR THE ESTABLISHMENT OF A PRESSURE DIFFERENTIAL AT OPPOSITE SIDES OF THE TUBE WALL UPON FLOW OF LIQUID UNDER PRESSURE FROM ONE SIDE OF THE WALL TO THE OTHER, SAID WIRES AND THEIR HELICAL RELATION TO EACH OTHER, AND SAID MEMBER PROVIDE FOR AUTOMATIC RETURN OF THE TUBE TO ITS ORIGINAL CONDITION UPON RELEASE OF THE TUBE WALL FROM SAID PRESSURE DEFFERENTIAL.