Surge control device for centrifugal compressors

Claim 1

A SURGE CONTROL DEVICE COMPRISING: A BY-PASS VALVE INCLUDING A TUBULAR VALVE BODY HAVING AN INLET CONNECTION FOR BY-PASS FLUID, SAID TUBULAR VALVE BODY BEING CLOSED AT ONE END AND OPEN AT THE OTHER END; A VALVE MEMBER IN THE OPEN END OF SAID TUBULAR VALVE BODY ARRANGED TO CONTROL FLOW OF BY-PASS FLUID THROUGH SAID BY-PASS VALVE; A FIRST DIAPHRAGM HAVING ITS PERIPHERAL PORTION ATTACHED TO THE SIDES OF SAID TUBULAR VALVE BODY; A VALVE STEM FASTENED AT ONE END TO SAID VALVE MEMBER AND EXTENDING INTO SAID TUBULAR VALVE BODY, THE OTHER END OF SAID VALVE STEM BEING SECURED TO SAID FIRST DIAPHRAGM; A RESTRICTED PASSAGEWAY FORMED IN SAID VALVE STEM AND CONNECTING ONE SIDE OF SAID FIRST DIAPHRAGM WITH A ZONE OF LOWER PRESSURE; A FIRST SPRING DISPOSED IN SAID TUBULAR VALVE BODY TO URGE SAID FIRST DIAPHRAGM IN A DIRECTION TO CLOSE SAID VALVE MEMBER; A RIGID WALL MOUNTED IN SAID TUBULAR VALVE BODY PARALLEL TO AND AXIALLY SPACED FROM SAID FIRST DIAPHRAGM TO FORM A FIRST CHAMBER, SAID DIAPHRAGM BEING ARRANGED TO EXCLUDE BY-PASS FLUID FROM SAID FIRST CHAMBER, SAID RIGID WALL IN COMBINATION WITH THE CLOSED END OF SAID TUBULAR VALVE BODY FORMING A SECOND CHAMBER; A SECOND DIAPHRAGM HAVING ITS PERIPHERAL PORTION ATTACHED TO THE SIDES OF SAID VALVE BODY AND DIVIDING SAID SECOND CHAMBER INTO TWO SECTIONS; A VALVE SEAT FORMED ON SAID RIGID WALL, SAID VALVE SEAT HAVING PASSAGE MEANS INCLUDING A RESTRICTED OPENING TO PERMIT FLUID COMMUNICATION BETWEEN ONE OF SAID SECTIONS AND SAID FIRST CHAMBER, ONE END OF SAID PASSAGE MEANS BEING LOCATED ADJACENT ONE SURFACE OF SAID SECOND DIAPHRAGM; A SECOND SPRING DISPOSED IN SAID SECOND CHAMBER TO URGE SAID SECOND DIAPHRAGM AWAY FROM THE SAID ONE END OF SAID PASSAGE MEANS; MEANS ADAPTED TO SENSE A FIRST FLUID PRESSURE AND A SECOND FLUID PRESSURE; AND CONDUIT MEANS FOR CONNECTING SAID FIRST AND SECOND FLUID PRESSURES TO THE OPPOSITE SECTIONS OF SAID SECOND CHAMBER, SAID SECOND DIAPHRAGM MODULATING IN RESPONSE TO THE FORCES ACTING ON OPPOSITE SIDES THEREOF SO THAT ONE SIDE OF SAID SECOND DIAPHRAGM COACTS WITH SAID VALVE SEAT TO OPEN AND CLOSE THE PASSAGE MEANS, THEREBY CONTROLLING THE FLOW OF SAID SENSED FLUID THROUGH SAID RESTRICTED OPENING INTO SAID FIRST CHAMBER TO OPERATE SAID VALVE MEMBER.