Pressure Control Valves is switched by the ecm. It function is to set the correct pressure in the rail and maintain the ecm plotted desired rail pressure. The flange is mounted either to the high pressure pump or to the rail.

Pressure Controlled Water Valves are balancing the temperature of mixed water. It eliminates a cylinder enclosing the pressure control piston and multiple seal rings, to reduce the number of parts and to minimize the productions. The structure of the piston within cylinder to enhance productivity of the valve. It comprises of additional backflow cutoff valves in each of hot and cold water outlet to prevent back flows of water. The initial control of water pressure is easy by this device because the piston is always placed in the center of the cylinder while water doesn't flow.

Pressure controllers consist of two chambers separated by a diaphragm, with a needle valve in the center actuated by the diaphragm. The diaphragm is held down by a spring that is adjustable. If the pressure falls in the upper cylinder, the diaphragm moves upward due to the pressure in the lower chamber. These are fine-tuned at the outer end of the cylinder and gain the rod side at the opposite end of the cylinder. This is associated with gas chromatograph. The reducing valves on the gas tanks are examples of simple pressure controllers. They are used for seat checking and to verify the pressure.