Pressure relief controller

Pressure relief controller is a direct-acting pipeline control valve designed to automatically maintain water pressure up to its setpoint along the flow direction.

The controller automatically maintains water pressure by adjusting the valve's passage area. When the pressure exceeds the set value, the controller opens until the water pressure equalizes with the specified level.

The principle of operation for a direct-acting controller is based on using water pressure to move the valve's shutter. The degree of opening is proportional to the deviation of the controlled pressure from the set value, hence they are also called proportional controllers.

Applications

Pressure relief controllers are installed in heating systems, heat substations, boiler rooms, and pumping stations, where they function as bypass or relief devices.

Advantages

• Easy to adjust
• High reliability
• No external power sources required
• High accuracy in pressure maintenance

Disadvantages

• High cost
• High demands on the quality of the heat transfer medium
• Range of supported pressures is limited by the spring compression force

Alternative names

• Pressure controller "to itself"
• Relief controller (valve)

Possible replacement

The relief controller can be replaced with an indirect-acting controller, which must include a pressure sensor, controller, and regulating valve with an electric actuator. Despite the higher precision in pressure maintenance, indirect-acting controllers are used only when direct-acting controllers cannot be applied, for example, if a DN200 valve or a very wide range of supported pressures is required.