As an independent valve:
Pressure control valves are used to control or limit the system pressure in a plant or to switch in response to a signal pressure.
Depending on the design a differentiation is made between seated valves and spool valvesthat can be directly or pilot-controlled. In relation to the function a differentiation is made between pressure-limiting valves and pressure-reducing valves.
In a valve-controlled pump:
Here it has the task of sealing the displacement chamber against the system pressure during the suction stroke of the piston. During the pressure stroke the pressure valve opens such that the piston can press the geometric displacement into the circuit.