The pressure relief holding valve utilizes hydraulic automatic operation and can be used as both a pressure relief valve and a holding valve. When used as a pressure relief valve, it can maintain the water supply pressure below the set value; Used as a pressure holding valve, it can maintain the upstream water pressure of the main valve above the set value and maintain the upstream water supply pressure of the main valve. The pressure relief holding valve utilizes hydraulic self control, does not require other devices or energy sources, is easy to maintain, and has multiple uses with one valve.

Pressure relief holding valves are mainly used in fire or other water supply systems to prevent system overpressure or maintain pressure in the fire water supply system. After the fire pump is turned off, the impact of water hammer can be reduced. Also used for water hammer devices in large-scale water supply systems. And the valve control system is equipped with a self-cleaning filter screen, which utilizes fluid characteristics to prevent suspended particles with high density and diameter from entering the control system. The system circulates unobstructed, allowing the valve to operate reliably. The system operates smoothly and has a long service life, suitable for pipelines with diameters below 600.

Working principle of pressure relief holding valve:

1. As a pressure relief valve: When the pressure relief holding valve is adjusted to the pressure relief state, water flows through the needle valve, main valve control room, ball valve A, pressure relief/holding pilot valve, and ball valve B to the outlet. At this time, the main valve is in the open state. When the pressure exceeds the set value of the pressure relief/holding valve, the pressure relief valve will automatically open and release some water through ball valve C to relieve the pressure in the pipeline. When the pressure returns to its value, the pressure relief valve automatically closes. When making a pressure relief valve, all ball valves are normally open.

2. Pressure holding valve: When the pressure relief pressure holding valve is adjusted to the holding state, as long as the main valve water pressure is lower than the set value of the pilot valve, the pilot valve will close. The main control room is pressurized and the main valve is closed. When the upstream water supply pressure of the main valve exceeds the set pressure of the pilot valve, the pressure holding pilot valve can be opened. The water in the control room is discharged to the outlet through the ball valve, and the pressure reducing main valve in the control room opens to start water supply, which maintains the upstream water pressure. When used as a pressure holding valve, the ball valve C should be normally closed or replaced with a plug.

Installation requirements for pressure relief holding valves:

Install a filter before using the pressure relief holding valve.

When adjusting, the screw on the pilot valve should be withdrawn. Start the water pump to release water through the pressure relief valve, gradually screw in the adjusting screw, and gradually increase the pressure. Until the desired set pressure is reached. Tighten the locking nut after setting.