Self sealing gate valve

Claim 1

A THROUGH CONDUIT GATE VALVE COMPRISED OF A HOUSING WITH A BORE THERETHROUGH, A VALVE CHAMBER INTERSECTING SAID BORE, A RECIPROCATING SLAB GATE MEMBER LOCATED IN SAID VALVE CHAMBER, SAID GATE MEMBER PROVIDED WITH A PASSAGE ALIGNABLE WITH THE BORE IN THE OPEN POSITION AND A SOLID PORTION TO COVER SAID BORE IN THE CLOSED POSITION, FACING ANNULAR RECESSES SURROUNDING SAID BORE, EACH RECESS HAVING AN END WALL INTERSECTING THE BORE, AN ANNULAR WALL COAXIAL WITH THE BORE, ONE SIDE OPEN TO THE BORE AND ONE END OPEN TO THE VALVE CHAMBER, A SEAT MEMBER IN EACH OF SAID RECESSES, EACH SEAT MEMBER FORMED OF AN ANNULAR RING HAVING A LESSER OUTER DIAMETER THAN THE ANNULAR WALL OF ITS RECESS WHEREBY EACH SEAT MEMBER LOOSELY FITS INTO ITS RECESS, EACH SEAT MEMBER PROVIDED WITH A PASSAGE ALIGNED WITH THE BORE, THE AXIAL LENGTH OF EACH SEAT MEMBER BEING GREATER THAN THE AXIAL LENGTH OF ITS RECESS WHEREBY A PORTION OF EACH SEAT MEMBER PROTRUDES INTO THE VALVE CHAMBER TO FORM A SEALING FACE FOR CO-OPERATION WITH A FACE OF THE GATE MEMBER, EACH SEALING FACE PROVIDED WITH AN ANNULAR GROOVE, A DEFORMABLE PLASTIC SEALING MEMBER POSITIONED IN SAID ANNULAR GROOVE, SAID DEFORMABLE PLASTIC SEALING MEMBER EXTENDING BEYOND THE PLANE OF THE SEALING FACE TO FORM AN ANNULAR RING OF SEALING CONTACT AREA, EACH SEAT MEMBER HAVING AN AXIALLY OUTWARD FACE WHICH OPPOSES THE END WALL OF ITS RECESS, THE RADIALLY OUTER CORNER OF SAID AXIALLY OUTWARD FACE PROVIDED WITH A RECTANGULAR NOTCH WHICH TOGETHER WITH THE CORNER FORMED BY THE END WALL AND THE ANNULAR WALL OF THE RECESS FORMS A RECTANGULAR CHAMBER, A RESILIENT O-RING POSITIONED IN SAID CHAMBER FORMING A SEAL BETWEEN THE SEAT MEMBER AND ITS RECESS, SAID O-RING HAVING AN INITIAL OUTER DIAMETER APPROXIMATING THE OUTER DIAMETER OF THE SEAT MEMBER AND A THICKNESS SUBSTANTIALLY LESS THAN THE RADIAL DEPTH OF THE CHAMBER AND GREATER THAN THE AXIAL LENGTH OF THE CHAMBER, THE GATE MEMBER, SEALING SURFACES OF THE SEAT MEMBER AND THE DISTANCE BETWEEN THE END WALLS OF THE RECESSES BEING SO PROPORTIONED THAT THERE IS A SLIGHT INTERFERENCE BETWEEN ALL SEALING SURFACES ON ASSEMBLY.