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.