Pressure reducing valve | Pressure reducing valve function | Pressure reducing valve installation requirements | Pressure reducing valve precautions

The role of the pressure reducing valve

    The working principle of the pressure reducing valve is to reduce the water pressure by the local resistance of the flow passage in the valve to the water flow. The range of the water pressure drop is automatically adjusted by the pressure difference between the inlet and outlet of the membrane or the piston connected to the valve flap. In recent years, some new types of pressure reducing valves have emerged, such as fixed ratio pressure reducing valves. The principle of constant pressure reduction is to use the water pressure ratio control of the floating piston in the valve body, and the pressure reduction ratio at the inlet and outlet ends is inversely proportional to the ratio of the piston area on the inlet and outlet sides. The pressure reducing valve works smoothly and without vibration; there is no spring in the valve body, so there is no spring corrosion and metal fatigue failure; the sealing performance is good and does not leak, so the pressure is reduced (when the water flows) and the static pressure is reduced (the flow rate is 0 o'clock); especially during decompression without affecting water flow.

    Although the water flow through the pressure reducing valve has a large head loss, it is still energy-saving in general because it reduces the waste of water and makes the system flow distribution reasonable and improves the system layout and working conditions. Each spring of the pressure reducing valve is only applicable within a certain range of outlet pressure, and the spring should be replaced beyond the range. In the case of high working temperature of the medium, a pilot piston type pressure reducing valve or a pilot bellows type pressure reducing valve is generally used. When the medium is air or water (liquid), it is generally preferred to use a direct acting membrane pressure reducing valve or a pilot diaphragm type pressure reducing valve. Where the medium is steam, a pilot piston type pressure reducing valve or a pilot bellows type pressure reducing valve should be used. For ease of operation, adjustment and maintenance, the pressure relief valve should normally be installed on a horizontal pipe.

Pressure reducing valve installation requirements

   1. The installation of the pressure reducing valve should be carried out after the water supply pipe network is tested and flushed. Number of inspections: full inspection. Inspection method: Check the pipeline pressure test and flushing record.

   2. The pressure reducing valve should be inspected before installation: its specifications and models should be consistent with the design; the connecting parts of the external control line and the pilot valve should not be loose; the appearance should be free of mechanical damage, and the foreign objects in the valve should be removed. Number of inspections: full inspection. Inspection method: check drawing, inspection and hand check

   3. The flow direction of the pressure reducing valve should be consistent with the water flow in the water supply pipe network. Number of inspections: full inspection. Inspection method: observation inspection.

   4. The filter should be installed on the inlet side and the control valve should be installed before and after it. Number of inspections: full inspection. Inspection method: observation inspection.

   5. The adjustable pressure reducing valve should be installed horizontally and the valve cover should be upward. Number of inspections: full inspection. Inspection method: observation inspection.

   6. Proportional pressure reducing valve should be installed vertically; when installed horizontally, the orifice of single breathing port pressure reducing valve should be downward, and the opening of double breathing port pressure reducing valve should be horizontal. Number of inspections: full inspection. Inspection method: observation inspection.

   7. When installing a pressure reducing valve without a pressure gauge, install a pressure gauge on the front and rear adjacent parts. Number of inspections: full inspection. Inspection method: observation inspection.

Pressure reducing valve installation precautions

1. For ease of operation and maintenance, the valve is generally mounted upright on a horizontal pipe.

2. The installation of the pressure reducing valve must be consistent with the direction of fluid flow in strict accordance with the direction of the arrow on the valve body. If the water quality is not clean and contains some impurities, the filter must be installed at the upstream inlet of the pressure reducing valve.

3. In order to prevent post-valve pressure overpressure, a pressure reducing valve should be installed at not less than 4M from the valve outlet.

4. The pressure reducing valve plays a certain role in the pipeline. In order to prevent the damage of the water hammer, a small expansion tank can also be installed to prevent damage to the pipeline and the valve. The filter must be installed in front of the inlet pipe of the pressure reducing valve. The expansion tank must be installed after the pressure relief valve outlet!

5. If the pressure relief valve needs to be installed in a hot water system, you must install a check valve between the pressure relief valve and the expansion tank. In this way, the expansion tank can absorb the volume of water increased due to thermal expansion, and can prevent the influence of hot water return or pressure fluctuation on the pressure reducing valve, and ensure the long-term normal operation of the pressure reducing valve.