Gas lift valve

Claim 1

A GAS LIFT VALVE, COMPRISING, (A) A GENERALLY TUBULAR CASING HAVING A PASSAGEWAY EXTENDING LONGITUDINALLY THEREOF AND OPENING AT SPACED POINTS TO THE EXTERIOR THEREOF, (B) GAS INJECTION PORTS THROUGH THE WALL OF THE CASING COMMUNICATING WITH SAID PASSAGEWAY INTERMEDIATE ITS ENDS, (C) A TUBULAR MAIN VALVE MEMBER COOPERABLE WITH AN ANNULAR SEAT IN SAID PASSAGEWAY BELOW THE GAS INJECTION PORTS, SAID MAIN VALVE MEMBER BEING CONNECTED TO SAID CASING VIA PRESSURE RESPONSIVE MEANS DEFINING WITH SAID CASING A CLOSED ANNULAR CHAMBER PRELOADED WITH GAS AT A PREDETERMINED PRESSURE, SAID PRESSURE RESPONSIVE MEANS BEING CONSTRUCTED AND ARRANGED SO THAT THE PRELOAD BIASES THE MAIN VALVE MEMBER TOWARD THE SEAT, (D) SAID PRESSURE RESPONSIVE MEANS BEING ARRANGED TO DEFINE A REACTOR SURFACE RESPONSIVE TO THE PRESSURE FROM SAID GAS INJECTION PORTS TO OPPOSE THE BIAS OF SAID PRELOADED PRESSURE, (E) AUXILIARY VALVE MEANS INCLUDING PASSAGEWAY-CLOSING MEANS POSITIONED IN SAID PASSAGEWAY ABOVE SAID PORTS AND COOPERABLE WITH SAID MAIN VALVE MEMBER IN RESPONSE TO THE RECIPROCATING MOVEMENT OF THE MAIN VALVE MEMBER FOR CONTROLLING FLUID FLOW UPWARDLY THROUGH SAID PASSAGEWAY, SAID AUXILARY VALVE MEANS BEING ACTUATABLE TO CLOSE SAID PASSAGEWAY WHEN THE MAIN VALVE MEMBER MOVES TO ITS OPEN POSITION AND TO OPEN SAID PASSAGEWAY WHEN THE MAIN VALVE MEMBER MOVES TO ITS CLOSED POSITION.