Relief valve

Claim 1

A PILOT OPERATED RELIEF VALVE FOR PRODUCING A SUBSTANTIALLY CONSTANT MASS FLOW RATE AT VARYING DOWNSTREAM PRESSURES COMPRISING A CASING FORMING A FIRST PASSAGEWAY FOR THE FLOW OF LIQUID IN A STRAIGHT LINE THERETHROUGH, THE CASING HAVING ADJACENT CONVERGING AND DIVERGING WALLS TO FORM A CAVITATING VENTURI THROAT IN THE PASSAGEWAY, AN ANNULAR WALL IN THE PASSAGEWAY UPSTREAM FROM THE VENTURI THROAT AND ATTACHED TO THE CASING AT SPACED POINTS, SAID ANNULAR WALL BEING CLOSED AT THE UPSTREAM END AND OPEN AT THE DOWNSTREAM END, A POPPET RELIEF VALVE HAVING A HEAD ENGAGING THE CONVERGING WALL TO CLOSE THE CONDUIT AND A STEM PROJECTING INTO THE OPEN END OF THE ANNULAR WALL TO FORM A CHAMBER, A SECOND PASSAGEWAY IN THE CASING, A TRANSVERSE WALL IN THE SECOND PASSAGEWAY HAVING AN OUTLET OPENING FORMING A VALVE SEAT, A PILOT VALVE IN THE SECOND PASSAGEWAY AT ONE SIDE OF THE TRANSVERSE WALL FOR CLOSING THE OUTLET OPENING, A SPRING ACTING ON THE PILOT VALVE TO MOVE IT TO CLOSED POSITION, A PISTON IN THE PASSAGEWAY AT THE OPPOSITE SIDE OF THE TRANSVERSE WALL FROM THE PILOT VALVE AND HAVING A STEM IN ALIGNMENT WITH THE PILOT VALVE, A SPRING ACTING BETWEEN THE TRANSVERSE WALL AND PISTON, A PASSAGE IN THE CASING CONNECTING THE FIRST PASSAGEWAY UPSTREAM FROM THE RELIEF VALVE TO THE SECOND PASSAGEWAY AT THE SIDE OF THE PISTON OPPOSITE THE STEM, A PASSAGE IN THE CASING CONNECTING THE CHAMBER BETWEEN THE ANNULAR WALL AND POPPET RELIEF VALVE IN THE FIRST PASSAGEWAY TO THE SECOND PASSAGEWAY BETWEEN THE PISTON AND PILOT VALVE, AND A CONNECTION BETWEEN THE SECOND PASSAGEWAY AT THE REAR OF THE PILOT VALVE AND THE DIVERGING WALL OF THE VENTURI THROAT DOWN STREAM FROM THE POPPET VALVE.