Pressure proportional regulator. Pressure proportional regulator is a device to control the output pressure by adjusting the inlet pressure, which is composed of spring and diaphragm. The diaphragm divides the container into two parts, one is the air inlet chamber and the other is the air outlet chamber. When the pressure in the inlet chamber changes, the diaphragm will bend, thus changing the pressure in the outlet chamber. The regulator is used to control the pressure proportional regulator and the electric proportional operator to make them proportional to the input signal.