Pressure Relief Valves

What is a Pressure Relief Valve?

Pressure Relief Valves are used to divert flow as the inlet pressure reaches the valve set pressure in order to maintain a pressure downstream. The most common form (direct acting) relies on the compression of a spring acting against a diaphragm or piston to keep the valve closed.

In the event of the inlet pressure rising above the set-point of the spring, the pressure will cause the spring to compress further as the valve opens to relieve the pressure through the outlet port or direct to atmosphere depending on the configuration. The valve will close again as soon as the inlet pressure falls below the set-point pressure.

These valves are often regarded as divert valves in pumped systems where a steady pressure must be maintained at all times and the divert valve returns the fluid directly to the reservoir as the system pressure exceeds the set point. As soon as demand reduces system pressure, the relief/divert valve closes to allow the pressure to build again.

Note that these valves are not safety relief valves and are just intended as simple flow control devices rather than safety valves.

Pressure Relief Valves

Low Pressure 5mbar to 3000mbar

Medium Pressure up to 50bar

High Pressure up to 400bar