Abstract: An axial assembly of pistons is axially disposed in the depending end of tubing in a gas well and packer set above the formation. Gas and fluid from the production zone enters the casing through an orifice below the piston assembly. Fluid in the annulus between the tubing and the casing creates a static head of back pressure against the orifice resulting in decreasing the gas pressure at the well head or flow line, which is sensed by pressure sensors to energize a compressor generating gas under pressure forced down the tubing to move piston rods and close the orifice. The gas pressure lifts the fluid in the annulus to the well head and flow line connected therewith. This cycle is repeated each time gas pressure falls below a predetermined pressure at the well head or flow line.

Abstract: Fluid pressure above a predetermined limit in a fluid pressure system is reduced by operating a relief valve, having its inlet port connected with the system, in a throttling action. A normally seated valve member is maintained in relief valve closed position by pneumatic pressure on a piston in a chamber of the relief valve. A fluid pressure sensor communicating with the inlet port generates a signal in response to fluid pressure above a predetermined limit received by a sensor signal processor energized by a source of electrical energy which releases pneumatic pressure in the chamber for a predetermined time interval allowing system fluid pressure to unseat the valve member and exhaust fluid pressure through the relief valve outlet port.