Safety valve

Claim 1

MEANS FOR CONTROLLING THE PRESSURE OF FLUID FLOWING THROUGH A CONDUIT COMPRISING: A VALVE BODY HAVING INLET AND OUTLET PORTS, AND A MAIN VALVE CONTROLLING COMMUNICATION THEREBETWEEN; SAID MAIN VALVE BEING EXPOSED TO THE FLUID FLOWING THROUGH SAID CONDUIT WHEREBY A FIRST PRESSURE IS EXERTED THEREAGAINST, IN A DIRECTION TENDING TO OPEN THE SAME; A FIRST MEANS, INCLUDING A FLUID PATH-DIRECTING VALVE, FOR DIVERTING A PORTION OF THE FLUID FLOWING THROUGH SAID CONDUIT AND APPLYING THE SAME AGAINST SAID MAIN VALVE TO EXERT A SECOND PRESSURE THEREAGAINST, IN A DIRECTION TENDING TO CLOSE THE SAME; A DIAPHRAGM; UPPER AND LOWER PLATES COOPERATING WITH EACH OTHER TO SUPPORT THE OUTER MARGINAL REGION OF SAID DIAPHRAGM THEREBETWEEN; ONE OF SAID PLATES BEING RECESSED TO PROVIDE A CYLINDER; A PISTON SLIDABLE IN SAID CYLINDER; A DISC; SAID PISTON AND SAID DISC COOPERATING WITH EACH OTHER TO SUPPORT THE INNER MARGINAL REGION OF SAID DIAPHRAGM THEREBETWEEN; A SECOND MEANS, RECEPTIVE OF A PORTION OF THE FLUID DIVERTED BY SAID FIRST MEANS, FOR APPLYING THE SAME, THROUGH A PASSAGE IN THE OTHER OF SAID PLATES, AGAINST SAID DIAPHRAGM TO EXERT A FIRST PRESSURE THEREAGAINST, NORMALLY IN BALANCE WITH THE FIRST AND SECOND PRESSURES EXERTED AGAINST SAID MAIN VALVE; A THIRD MEANS, INCLUDING A LINKAGE SYSTEM, FOR APPLYING, THROUGH SAID PISTON AND SAID DISC, A SECOND PRESSURE AGAINST SAID DIAPHRAGM IN OPPOSITION TO SAID FIRST PRESSURE APPLIED THEREAGAINST AND EQUAL TO THE PRESSURE AT WHICH IT IS DESIRED TO OPEN SAID MAIN VALVE; AND A FOURTH MEANS, INTERPOSED BETWEEN SAID FLUID PATH-DIRECTING VALVE AND SAID LINKAGE SYSTEM, AND OPERABLE UPON SAID FIRST PRESSURE EXERTED AGAINST SAID DIAPHRAGM EXCEEDING SAID SECONDPRESSURE EXERTED THEREAGAINST, FOR CAUSING SAID FLUID PATHDIRECTING VALVE TO DISCONTINUE THE APPLICATION OF SAID SECOND PRESSURE AGAINST SAID MAIN VALVE AND PERMIT THE FLUID PREVIOUSLY APPLIED THEREAGAINST TO FLOW TO THE OUTLET PORT OF SAID VALVE BODY.