Spherical valve

Claim 1

A SPHERICAL VALVE COMPRISING A HOUSING HAVING A CENTRAL CHAMBER COMMUNICATING WITH A FLOW PASSAGE, A BALL ROTOR HAVING A PASSAGEWAY THERETHROUGH AND HAVING A SOLID SURFACE THEREON, MEANS FOR MOUNTING SAID BALL ROTOR IN SAID CHAMBER FOR ROTATION BETWEEN ONE POSITION WITH SAID PASSAGEWAY CONNECTING WITH SAID FLOW PASSAGE AND ANOTHER POSITION WITH SAID SOLID SURFACE SPANNING SAID FLOW PASSAGE, A BASE RING AND A CLOSURE RING MOUNTED IN SAID HOUSING AND SPACED APART TO LEAVE A GAP AND FORMING A GROOVE SURROUNDING SAID FLOW PASSAGE, SAID RINGS DEFINING THE SHAPE OF SAID GROOVE TO PROVIDE A CHAMBER PORTION REMOTE FROM SAID BALL ROTOR AND HAVING A PREDETERMINED WIDTH AND TO PROVIDE A CONICAL CHANNEL PORTION NARROWER THAN SAID CHAMBER PORTION AND EXTENDING RADIALLY OF SAID BALL ROTOR BETWEEN SAID CHAMBER PORTION AND SAID CENTRAL CHAMBER, MEANS IN SAID BASE RING DEFINING A PRESSURE PASSAGE TO A REMOTE PART OF SAID CHAMBER PORTION, A CONICAL ELASTOMERIC SEALING RING IN SAID GROOVE AND ENGAGING SAID BALL ROTOR, SAID SEALING RING BEING OF LARGER FREE CROSS SECTION THAN SAID CHANNEL AND OF LARGER FREE CROSS SECTION THAN SAID CHAMBER PORTION EXCEPT FOR SAID REMOTE PART THEREOF AND URGING SAID BASE RING AND SAID CLOSURE RING APART TO ENLARGE SAID GAP, AND MEANS IN SAID HOUSING AND ENGAGING SAID CLOSURE RING FOR LIMITING THE SIZE OF SAID GAP.