How the pressure reducing valve works:
Definition of decompression: The use of throttling methods to make the outlet pressure lower than the inlet pressure.
Overview of Pressure Reducing Valves:
The pressure reducing valve is a valve that reduces the inlet pressure to a certain required outlet pressure by adjusting it, and relies on the energy of the medium itself to automatically maintain a stable outlet pressure. From the point of view of fluid mechanics, the pressure reducing valve is a throttling element whose local resistance can change, that is, by changing the throttling area, the flow rate and the kinetic energy of the fluid are changed, resulting in different pressure losses, so as to achieve the purpose of pressure reduction. Then, relying on the adjustment of the control and regulation system, the fluctuation of the pressure behind the valve is balanced with the spring force, so that the pressure behind the valve is kept constant within a certain error range.
A pressure reducing valve is a specialized device that automatically reduces the working pressure of the pipeline, which can reduce the high water pressure of the line in front of the valve to the level required for the line behind the valve. Pressure reducing valves are widely used in high-rise buildings, areas with excessive water pressure in urban water supply networks, mines and other occasions to ensure that each water point in the water supply system receives the appropriate service water pressure and flow. In view of the fact that the leakage rate and waste degree of water are almost proportional to the water pressure of the water supply system, the pressure reducing valve has the effect of improving the operating conditions of the system and potential water saving, and its water saving effect is about 30% according to statistics.
The structure of the pressure reducing valve: The structure of the pressure reducing valve is divided into two types: piston type and diaphragm type.
Body material: Brass nickel plated.
Spool: Stainless steel.
Spring: carbon steel.
Sealing material: NBR rubber.
How to adjust the size of the pressure reducing valve:
When the output pressure of the pressure reducing valve is high or the diameter is large, the spring stiffness will inevitably be too large when the pressure regulating spring is directly regulated, and when the flow rate changes, the output pressure fluctuates greatly, and the structural size of the valve will also increase.
The adjustment is carried out according to the working principle of the pressure reducing valve, and the adjustment is based on the following conditions:
The pressure reducing valve is to reduce the water pressure by the local resistance of the flow channel in the valve, and the range of water pressure drop is automatically adjusted by the membrane connected to the valve disc or the inlet and outlet water pressure difference on both sides of the piston. The principle of constant ratio pressure reduction is controlled by the water pressure ratio of the floating piston in the valve body, and the pressure reduction ratio at the inlet and outlet ends is inversely proportional to the area ratio of the piston at the inlet and outlet sides.
This type of pressure reducing valve works smoothly and without vibration; There is no spring in the valve body, so there is no worry about spring corrosion and metal fatigue failure; The sealing performance is good and there is no leakage, so it reduces both dynamic pressure (when water flows) and static pressure (when the flow rate is 0); In particular, the pressure is reduced without affecting the water flow.
Commissioning of pressure reducing valves
1. The dynamic and static pressure of the pressure reducing valve before and after the valve should meet the design requirements.
2. The outflow rate of the pressure reducing valve should meet the design requirements, when the outflow rate is 150% of the design flow, the dynamic pressure behind the valve should not be less than 65% of the rated design working pressure.
3. The regulator should not have a significant increase in noise at low flow, design flow and 150% of design flow.
4. The dynamic and static pressure difference behind the test pressure reducing valve should meet the design requirements.
How to adjust the tap water pressure reducing valve?
1. The pressure regulation range is mainly related to the stiffness of the pressure regulating spring, and the pressure regulation range is within the specified range of the output pressure P2 of the water pipe pressure reducing valve, and it must be ensured to reach the specified accuracy. When the flow rate g is a constant value, the fluctuation of the input pressure will cause the fluctuation of the output pressure. The smaller the output pressure fluctuates, the better the characteristics of the pressure reducing valve, so the output pressure must be lower than the input pressure—a fixed value so that the pressure range does not change with the input pressure. At the input pressure-timing, the output pressure will vary with the output flow rate g.
2. Close the on-off valve before the pressure reducing valve, open the on-off valve after the pressure reducing valve, create a downstream low-pressure environment, rotate the adjusting screw counterclockwise to the upper position (relatively low outlet pressure), and then close the on/off valve after the pressure reducing valve.
3. Slowly open the on/off valve in front of the pressure reducing valve until it is fully open, slowly rotate the adjusting screw clockwise, and adjust the outlet pressure to the required pressure (subject to the gauge pressure behind the valve); After adjustment, lock the lock, lock the nut, and open the gate valve after the pressure reducing valve; It should be noted that it can only be adjusted from low pressure to high pressure.