Importance

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Abstract

A pressure controller is provided for a pressure regulator. The pressure controller controls a pressure regulator to deliver process fluid at a regulated pressure from a variable supply. The pressure controller includes a control pressure source independent of the process fluid. One such pressure source could be compressed air which enters the controller through a restriction. The control pressure passes through the controller to the regulator where it exerts pressure on the pressure regulator. The controller is interconnected with the process fluid line at a point of regulation and senses pressure in a diaphragm chamber of the controller. A valve rides on the diaphragm and a bias is exerted against the valve to oppose pressure on the diaphragm. The bias tends to move the valve to a closed position. The bias means is adjustable. The process fluid pressure in the diaphragm chamber exerts a force on the diaphragm and valve, against the bias, to open the valve. As pressure in the diaphragm chamber rises, corresponding to a rise in the process fluid pressure, the diaphragm is moved to open the valve to allow the flow of control pressure through the valve to atmosphere or drain. If the regulated pressure falls below a set point, the valve closes and control pressure is not vented to atmosphere, but flows directly to the regulator to increase pressure on the regulator to increase the pressure of the process fluid. At set pressure, the valve is partially open to allow sufficient flow to atmosphere or drain to maintain a steady pressure on the pressure regulator. Feedback to the regulator is thus provided based on process fluid pressure sensed by the controller at a point of regulation without the need for electronics.

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First Claim