Pressure Relief / Sustaining Valve

1. Product Overview

Pressure Relief / Sustaining Valve, commonly known as Model 500X hydraulic control valve, is a diaphragm-type hydraulically operated pilot valve for water pipeline systems.

When fitted with a solenoid pilot actuator, it becomes the 600X Solenoid Controlled Pressure Relief/Sustaining Valve as shown in the picture, combining remote electric on-off control with dual pressure protection functions.

The valve body is cast from QT450 nodular cast iron with blue epoxy anti-corrosion coating, standard flanged connection, PN10/PN16 pressure class. It runs fully on pipeline water pressure without external power supply, widely used in municipal water supply, pump stations, fire fighting, irrigation and industrial circulating water systems.

2. Dual Core Working Functions (Relief + Sustaining)

Function 1: Pressure Sustaining (Back Pressure Holding)

The valve maintains a stable minimum preset upstream inlet pressure. If downstream water consumption surges and inlet pressure falls below the set value, the valve automatically closes to lock upstream pressure and avoid pipeline negative pressure or pump cavitation.

Function 2: Pressure Relief (Overpressure Surge Protection)

When pipeline pressure rises above the upper safety threshold (caused by pump shutdown, sudden valve closing or peak water use), the pilot triggers the main valve to open and drain excess pressure to the bypass or drain pipe, preventing pipe burst, water hammer shock and damage to pumps, meters and pipe fittings.

Solenoid Add-on (600X Model in Picture)

The attached electromagnetic pilot allows remote electric signal control to manually open/close the relief/sustaining function. The top red manual needle valve adjusts opening/closing speed to eliminate destructive water hammer surges during pressure regulation.

3. Key Features

Dual Function Integration: Single valve completes pressure sustaining and overpressure relief, saves pipeline installation space and cost.

Solenoid Optional Control: AC220V / DC24V solenoid pilot available for remote automatic control (600X series).

Adjustable Surge Protection: Built-in flow needle valve for slow open/close, effectively reduces water hammer impact.

Robust Durable Construction: QT450 ductile iron body, brass pilot tubing, EPDM/NBR soft seal for zero leakage.

Self-Powered Hydraulic Drive: No motor or air source required, relies entirely on medium pressure for operation, low energy consumption.

Easy Maintenance: Split main valve design, pilot components replaceable without removing the valve from the pipeline.

4. Typical Application Scenarios

Water supply pump station outlet pressure stabilization & overpressure protection

High-rise building domestic & fire water pipeline pressure control

Farmland irrigation main pipe surge relief

Industrial factory cooling circulating water system

Reservoir, water plant pressure buffer protection

5. Technical Specs (DN100 PN16 as reference)

Model: 500X-16Q / 600X-16Q (Solenoid Controlled Type)

Nominal Diameter: DN50 ~ DN600

Pressure Class: PN10, PN16

Body Material: QT450 Nodular Cast Iron

Sealing Material: EPDM Rubber

Connection Standard: GB, ANSI, DIN Flange

Medium: Clean raw water, tap water, fire water

Working Temp: 0℃ ~ 80℃

Solenoid Voltage (600X only): DC24V, AC110V, AC220V