Combined pressure regulator and relief valve

Claim 1

IN A COMBINATION WITH A RESERVOIR TANK A PRESSURE REGULATOR AND RELIEF VALVE ADAPTED TO BE MOUNTED IN A WALL OF THE TANK AND COMPRISING A BODY HAVING A (A) CYLINDRICAL CHAMBER AND AN ANNULAR RECESS THEREIN, (B) SAID BODY HAVING FIRST AND SECOND PORTS AFFORDING COMMUNICATION BETWEEN SAID CHAMBER AND THE TANK INTERIOR, (C) A PISTON RECIPROCABLE IN SAID CHAMBER AND HAVING OPPOSED END FACES HAVING RELATIVELY DIFFERENT EFFECTIVE AREAS ON WHICH PRESSURE FLUID MAY ACT, (D) SAID PISTON HAVING AN ANNULAR RECESS INTERMEDIATE THE END FACES THEREOF, (E) SPRING MEANS ACTING AGAINST THE FACE OF THE PISTON HAVING THE RELATIVELY SMALLER AREA TO BALANCE THE PRESSURE DIFFERENTIAL ON THE OPPOSITE FACE OF SAID PISTON, (F) SAID BODY HAVING FIRST PASSAGE MEANS AND AN INLET PORT COMMUNICATING WITH SAID CHAMBER, (G) MEANS CONNECTING SAID PASSAGE TO A SUPPLY OF PRESSURE FLUID, (H) SAID BODY HAVING A RELIEF PASSAGE COMMUNICATING WITH SAID FIRST MENTIONED RECESS AND OPENING TO THE ATMOSPHERE, (I) SAID PISTON WHEN THE PRESSURE IN SAID TANK EXCEEDS A PREDETERMINED POINT BEING CAUSED TO MOVE IN A DIRECTION TO CLOSE SAID INLET PORT THEREBY TO SHUT OFF THE FLOW OF PRESSURE FLUID INTO SAID TANK RESERVOIR AND TO EFFECT COMMUNICATION BETWEEN SAID SECOND PORT AND SAID RECESSES WHEREBY EXCESS PRESSURE FLUID FROM SAID TANK MAY VENT THROUGH SAID RELIEF PASSAGE.