The pressure regulating valve can basically be said to be a pressure reducing valve. The working principle of the pressure reducing valve is as follows: high-pressure medium is filled into a relatively large cavity through a small hole to achieve pressure reduction. In fact, pressure reduction is achieved by cutting off the flow, diaphragm or piston. One of the two sides is the outlet port, and the other side is the artificial pressure, and the valve stem that controls the size of the small hole is connected to the diaphragm (piston). In this way, as long as a fixed pressure is given, the pressure in the outlet port will always be equal to this pressure. This artificially given pressure can be provided by a spring or a pneumatic or hydraulic source.