Pilot-Operated Pressure Reducing Valves

At Metalsin, we supply pilot-operated pressure reducing valves for waterworks. Such a pressure reducing valve is a pilot-operated, diaphragm-type hydraulic control valve that utilizes the pipeline’s own hydraulic pressure for operation. Its pilot mechanism regulates the main valve, ensuring that both hydrostatic and dynamic outlet pressures remain stable at the preset value despite fluctuations in inlet pressure or changes in outlet flow rate. Moreover, the outlet pressure can be adjusted within a specified range to meet client requirements.

Design Features

Pilot-operated pressure reducing valves for waterworks.

• Optimized Valve Body Design: The valve body features a spherical, Y-shaped structure with a full-diameter design that delivers strong flow capacity and low head loss. Its well-engineered flow channels minimize the formation of harmful flow patterns such as turbulence, thereby reducing cavitation hazards.
• Easy-Maintenance Diaphragm: The diaphragm is designed as a single unit that can be assembled and disassembled easily for maintenance. Acting as a soft piston, it ensures jam-free operation, offers sensitive movement, and delivers precise control.
• Dual-Chamber Main Valve: The main valve employs a dual-chamber structure to protect the diaphragm from the impacts of high-pressure water, sediment, and debris. This robust design extends the diaphragm’s service life to up to 1 million cycles.
• Self-Cleaning External Connection: The external connecting pipe is equipped with a built-in self-cleaning strainer, ensuring that the valve body remains maintenance-free.
• Autonomous Operation: The valve operates automatically within pipeline systems without the need for external power, which saves energy and supports truly unmanned operation.
• Wide Pressure Regulation Range: It provides a broad range of pressure regulation with stable performance, effectively reducing both dynamic and static pressures and minimizing the need for secondary adjustments when the pump stops and restarts.

Working Principles

The pilot-operated pressure reducing valve consists of an adjustable pressure reducing pilot valve, the main valve, a needle valve, a compact strainer, a ball valve & manifold tubing.

Diagram illustrating the operating principles of the pilot-operated pressure reducing valve.

Under normal conditions, water continuously flows into the main valve’s upper control chamber (chamber 2) via the needle valve (component 1) at the inlet. The pilot valve (component 3) is preset to the desired pressure. When the downstream pressure exceeds this set value, the pilot valve senses the increase and gradually closes. This closure causes the pressure in the upper control chamber to build up, prompting the main valve to slowly close, which in turn reduces the downstream pressure to the set level. Conversely, if the downstream pressure drops below the preset value, the pilot valve gradually opens, releasing the accumulated pressure in the upper chamber and allowing the main valve to slowly open.

An orifice (component 4) in the main valve’s middle chamber ensures a smoother response. Additionally, the ball valve located downstream of the pilot valve can be adjusted for different operating conditions to limit the discharge rate of the control chamber water flow, thereby stabilizing the main valve’s performance. If needed, this ball valve can be manually closed to provide an emergency shut-off.

Technical Specification

Technical drawing of pilot-operated pressure reducing valves for waterworks.

The pilot-operated pressure reducing valves supplied by Metalsin are designed and manufactured in accordance with a series of international standards such as AWWA C530, EN 1567, CJ/T 219, CJ/T 256, JB/T 10674, and GB/T 12246. Generally, they are rated for nominal working pressures of PN10, PN 16 (BS, DIN, EN & China standards) or 175 psi, 200 psi, 250 psi, or 300 psi (ANSI standards). Epoxy powder coated in RAL 5005 or 5015 color.

Click to view the dimensions and flow characteristics for pilot-operated pressure reducing valves with ASME B16.1 Class 125 flanged ends and EN 1092-2 flanged ends.