Piston valve seal

Claim 1

IN VALVE APPARATUS HAVING A FLUID PASSAGE: FIRST AND SECOND VALVE MEMBERS MOVABLE WITH RESPECT TO EACH OTHER TO CONTROL FLOW OF FLUID THROUGH SAID PASSAGE; ONE OF SAID MEMBERS HAVING A PERIPHERAL SEALING SURFACE; SEAL MEANS ON THE OTHER OF SAID MEMBERS ENGAGEABLE WITH SAID SURFACE TO CLOSE SAID PASSAGE; SAID MEMBERS BEING MOVABLE WITH RESPECT TO EACH OTHER TO DISENGAGE SAID SEAL MEANS FROM SAID PERIPHERAL SURFACE TO OPEN SAID PASSAGE; SAID SEAL MEANS INCLUDING A PLIANT, ELASTIC RING HAVING A PORTION, THE PERIPHERAL SURFACE OF WHICH IS ENGAGEABLE WITH SAID SEALING SURFACE, AND A CIRCUMFERENTIALLY ENDLESS LATERALLY THIN METALLIC, ELASTIC RING TO ONE SIDE OF SAID PORTION HAVING INITIAL WORKING CLEARANCE WITH SAID SEALING SURFACE AND ENGAGING AND ADAPTED TO BE DEFLECTED BY SAID PLIANT RING TOWARD SAID SEALING SURFACE TO FORCE A PERIPHERAL SURFACE OF SAID METALLIC RING AGAINST SAID SEALING SURFACE WHEN SAID PLIANT RING IS SUBJECTED TO PRESSURE; SAID METALLIC, ELASTIC RING EXTENDING TO AN END OF SAID PLIANT RING.