working principle of 200X Diaphragm Pressure Reducing Valve
The inlet pressure P1 enters the control chamber of the main valve through the conduit and needle valve 18 (see structural diagram), and establishes a downward pressure P3. The outlet pressure P2 also acts on the diaphragm (or piston) of the pilot valve through the conduit and opposes the regulating spring of the pilot valve. When the downstream pressure exceeds the set value of the pilot valve spring, the pilot valve closes, and the water discharge in the control chamber is 0. When the variable pressure P3 reaches its maximum value, the main valve disc tightly presses the valve seat and the pressure reducing valve closes. Once the downstream pressure P2 drops to the set value of the pilot valve spring, the pilot valve opens and the pressure water in the control room will be discharged downstream through pilot valve 9 and ball valve 6. Due to the small opening of the needle valve and the smaller diameter of the inlet duct compared to the outlet duct, the discharge rate is greater than the inlet pressure replenishment rate. As a result, the pressure P2 in the control room decreases, and the inlet pressure P1, which has been acting under the main valve disc, lifts the main valve disc and opens the pressure reducing valve. In the fixed adjustment state, the discharge flow rate is equal to the replenishment flow rate, the opening of the main valve remains unchanged, and the downstream pressure is stable. (This is the working principle of diaphragm type, and the same applies to piston type.)

Diaphragm type structural diagram
The valve consists of a main valve, a pilot valve, a needle valve, a ball valve, a micro filter, and a pressure gauge. Due to the fact that pilot valves, needle valves, and pressure gauges need to be connected to the main valve through conduits, they are collectively referred to as conduit control systems. Depending on the requirements of different pipe diameters, they can be divided into diaphragm and piston types
Main parts and materials
| 编号No. | 零件名称Part Name | 材 质Material | | 编号No. | 零件名称Part Name | 材 质Material |
| 1 | 阀 体Valve body | 铸铁、不锈钢Cast iron, stainless steel | 10 | 球 阀Ball valve | 铜Copper |
| 2 | 阀 座Valve seat | 铜、不锈钢Copper, stainless steel | 11 | 压力表Pressure gauge | |
| 3 | 密封垫Gasket | 强化橡胶Reinforced rubber | 12 | 压缩弹簧Compression spring | 不锈钢Stainless steel |
| 4 | 密封垫压板Gasket pressure plate | 铜、不锈钢Copper, stainless steel | 13 | 阀 杆Valve stem | 不锈钢Stainless steel |
| 5 | 阀 盘Valve disc | 铜、不锈钢Copper, stainless steel | 14 | 阀 盖Valve cover | 铸铁、不锈钢Cast iron, stainless steel |
| 6 | 球 阀Ball valve | 铜Copper | 15 | 针 阀Needle valve | 铜Copper |
| 7 | 膜 片Diaphragm | 强化橡胶Reinforced rubber | 16 | 球 阀Ball valve | 铜Copper |
| 8 | 膜片压板Diaphragm pressure plateмембраны | 铜、不锈钢Copper, stainless steel | 17 | 压力表Pressure gauge | |
| 9 | 导 阀Pilot valve | 铜Copper | 18 | 微型过滤器Microfilter | 不锈钢Stainless steel |