The working principle of the pressure reducing valve 

From the perspective of fluid mechanics, a pressure reducing valve is a throttling element with variable local resistance. That is, by changing the throttling area, the flow velocity and the kinetic energy of the fluid change, resulting in different pressure losses, thereby achieving the purpose of pressure reduction. It relies on the regulation of the control and regulation system to make the fluctuation of the pressure after the valve balance with the spring force, so that the pressure after the valve remains constant within a certain error range. 

(2) The pressure reducing valve can reduce the high liquid pressure in the pipeline before the valve to the required level in the pipeline after the valve. The transmission medium of the pressure reducing valve is mainly water. It is widely used in high-rise buildings, areas with excessive water pressure in urban water supply networks, mines, and other places to ensure that each water-using point in the water supply system obtains the appropriate service water pressure and flow rate. Given 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 potential to improve the operating conditions of the system and save water. According to statistics, its water-saving effect is approximately 30%. 

(3) The working principle of the pressure reducing valve is to adjust the inlet pressure to a certain required outlet pressure, and by relying on the energy of the medium itself, the outlet pressure will automatically remain stable. 

What are the installation precautions for pressure reducing valves? 

(1) For the convenience of daily operation and maintenance, pressure reducing valves are generally required to be installed upright on horizontal pipelines. When installing the pressure reducing valve, it must be done strictly in accordance with the arrow direction indicated on the valve body. It is necessary to ensure that it is consistent with the direction of fluid flow. If the water quality is not clean and contains some impurities, a filter must be installed at the upstream water inlet of the pressure reducing valve to avoid affecting the normal operation of the pressure reducing valve. 

(2) To prevent overpressure in the valve outlet, a pressure reducing valve should be installed at a distance of no less than 4 meters from the valve outlet. The pressure reducing valve plays a certain backflow prevention role in the pipeline. To avoid the hazards of water hammer, a small expansion water tank can also be installed to prevent damage to the pipeline and valves. The filter must be installed before the inlet pipe of the pressure reducing valve, while the expansion water tank must be installed after the outlet pipe of the pressure reducing valve. 
(3) If the pressure reducing valve needs to be installed in the hot water system, you must install a check valve between the pressure reducing valve and the expansion water tank. This arrangement enables the expansion water tank to absorb the increased volume of water due to thermal expansion, and also prevents the backflow of hot water or pressure fluctuations from affecting the pressure reducing valve, ensuring its long-term normal operation.