Removable gas control valve for oil wells

Claim 1

A GAS LIFT SYSTEM FOR RAISING OIL IN OIL WELLS COMPRISING A CASING FORMING A PRESSURE CHAMBER A TUBING IN SAID CASING, TO FORM A FLOW CONDUIT FOR THE RAISED OIL, A PLURALITY OF FITTINGS IN SAID TUBING AT SPACED ELEVATIONS THROUGH WHICH SAID RAISED OIL FLOWS, VALVE RECEIVING AND SUPPORT MEANS IN EACH OF SAID FITTINGS, SAID RECEIVING AND SUPPORT MEANS IN EACH OF SAID FITTINGS HAVING AN INTERNAL DIAMETER, WITH THE LARGEST DIAMETER IN THE FITTING LOCATED AT THE HIGHEST ELEVATION AND THE DIAMETER DECREASING IN THE FITTINGS SUCCESSIVELY DOWNWARDLY OF THE TUBING WITH THE SMALLEST DIAMETER IN THE FITTING LOCATED AT THE LOWEST ELEVATION WHEREBY ACCESS MAY BE HAD TO THE LOWERMOST OF SAID FITTINGS IN SAID TUBING THROUGH SAID FITTINGS THEREABOVE IN SAID TUBING AND VALVES ADAPTED TO BE LOWERED INTO SAID FLOW CONDUIT AND SEATED WITHIN SAID RECEIVING AND SUPPORT MEANS, EACH OF SAID VALVES HAVING AN EXTERNAL DIAMETER CORRESPONDING TO THE INTERNAL DIAMETER OF ITS SAID RECEIVING AND SUPPORT MEANS WHEREBY THE LARGEST DIAMETER VALVE IS SEATED WITHIN THE SAID LARGEST DIAMETER RECEIVING AND SUPPORT MEANS AND THE SAID SMALLEST DIAMETER VALVE SEATED WITHIN SAID SMALLEST DIAMETER RECEIVING AN SUPPORT MEANS AT THE LOWEST ELEVATION.