Product Introduction

This valve is a new-type product developed by our engineering technicians with reference to advanced counterparts from the US, France and domestic markets. It adopts hydraulic operation and automatic control via pressure difference in the control pipeline to automatically open/close and shut off the main valve, ensuring upstream pressure does not exceed a set value.

The valve body features a full-channel streamlined design, offering low fluid resistance, excellent sealing performance and sensitive automatic opening/closing response. Its key advantage is dual functionality as both a pressure relief valve and a pressure sustaining valve:

As a pressure relief valve, it releases pressure in water supply pipelines exceeding the pilot valve’s safe set value, maintaining pressure below the safe threshold to prevent pipeline/equipment damage from overpressure or sudden pressure surges. It is applicable to fire test circulation systems in high-rises and other water supply systems to avoid system risks from excessive water pressure.

As a pressure sustaining valve, it maintains upstream water supply pressure above a set value to ensure stable pressure in upstream supply areas, mainly for urban low-pressure water supply zones.

In summary, it is an ideal product for water supply systems. Welcome to purchase.

500X Piston Type Pressure Relief/Sustaining Valve Product Diagram

Working Principle and Application

When used as a pressure relief valve, the main valve is installed in the drainage bypass, i.e., in parallel with the main pipeline. When the upstream pressure gradually rises above the set value of pilot valve 13, the main valve opens quickly to drain water and reduce pressure. It only closes slowly and smoothly when the upstream pressure drops below the set value of pilot valve 13, avoiding water hammer and ensuring the safety of the pipeline. When functioning as a pressure relief valve, it is mainly used to eliminate excessively high pressure that gradually increases due to supply exceeding demand, such as in the initial stage of fire fighting in fire hydrant systems, automatic sprinkler systems, and at the outlet of water pumps in various water supply systems. When used as a pressure relief valve, ball valve 12 is normally open.

When used as a pressure retaining valve, the main valve is installed on the main pipeline, i.e., in series with the main pipeline. The main valve remains closed as long as the water supply pressure upstream of the main valve is lower than the set value of pilot valve 13. It will automatically open to supply water to the downstream when the upstream pressure exceeds the set value of pilot valve 13, thus ensuring the water supply pressure upstream of the main valve. It is mainly used to maintain the minimum water supply pressure of urban main pipes. Especially in case of fire, it can prevent branch users from excessive water pumping which would reduce the pressure. When used as a pressure retaining valve, ball valve 12 is normally closed or replaced with a pipe plug.