Swing type check valve

Claim 1

A SWING TYPE CHECK VALVE COMPRISING, A VALVE HOUSING MEMBER HAVING A VALE SEAT; A DISC MEMBER PIVOTABLY MOUNTED IN SAID HOUSING AND ADAPTED TO NORMALLY ENGAGE SAID SEAT TO CLOSE THE CHECK VALVE, SAID DISC MEMBER BEING RESPONSIVE TO FLOW THROUGH SAID HOUSING IN ONE DIRECTION TO MOVE AWAY FROM SAID SEAT; A MAGNETIZABLE COMPONENT CONNECTED TO ONE OF SAID MEMBERS AND A MAGNET COMPONENT CONNECTED TO THE OTHER OF SAID MEMBERS; SAID COMPONENTS HAVING SUCH RELATIVE POSITION IN RESPECT TO EACH OTHER, THAT SAID COMPONENTS EXERT A MAGNETIC CLOSING BIAS UPON SAID DISC MEMBER WHEN SAID DISC MEMBER ENGAGES SAID SEAT, AND THAT SAID MAGNETIZABLE COMPONENT MOVES (RELATIVE TO SAID MAGNET COMPONENT) OUT OF THE EFFECTIVE MAGNETIC FORCE OF SAID MAGNET COMPONENT WHEN SAID DISC MEMBER MOVES AWAY FROM SAID VALVE SEAT; AND SPRING MEANS INTERPOSED BETWEEN ONE OF SAID COMPONENTS AND THE MEMBER TO WHICH IT IS CONNECTED TO THEREBY PERMIT LIMITED RELATIVE MOTION BETWEEN SAID COMPONENTS INDEPENDENTLY OF THE RELATIVE MOTION BETWEEN SAID AND DISC MEMBERS.