ZDL series automatic recirculation valve is a kind of pump protection device. It automatic protect centrifugal pump when pump body occur cavitation damage or unstable (especially conveying hot water at low load operation medium). Once pump flow is lower than the preseted flow, bypass can completely open to ensure the minimum required flow pump. Even running fully closed, namely running flow is zero, the minimum flow can also pass bypass for Automatic Recycle. Pressure reduced through the multistage bypass pressure reducing valve.
ZDL series is suitable for bypass with medium or low pressure differential, maximum pressure differential is 6MPa, and specific choice is determined by factory.
Unique L bypass can eliminated noise by made high-speed flow medium, and prevent cavitation.
- Multi-cage type bypass, low noise, suitable for medium and low pressure working conditions.
- Forged valve body, can choose carbon steel or stainless steel material, etc.
- Standard bypass non-return function, maximum working pressure differential is 6MPa.
- With venturi port main flow non-return structure, adapt to complicated conditions.
- Pressure grade from PN16 to PN100, diameter from DN2to DN500.
- Can select manual bypass operation function, used in fault.
Size and pressure range
- Body type: Three-way forged body.
- Nominal diameter: DN25, 32, 40, 50, 65, 80,100, 200, 250, 300, 350, 400, 450, 500.
- Nominal pressure: PN 16, 25, 40, 64, 100 CLASS 150, 300, 600 LB.
- End connection: Flange, FF, RF, RTJ, BW,SW etc.
Material applicable temperature
|SS winding gasket||-20～+300||-40～+300||-196～+300||-196～+300|
|ZD||L||Nominal pressure||Body material||Nominal diameter||/Bypass diameter||Structure type|
|Automatic Recycle Pump Protection Valve||L type bypass assembly||PN16=PN16
|DN25=25 NPS1″=1″||V = Vertically mounted
H = Horizontally mounted
S = manual startup
|Such as: L type automatic recirculation valve, pressure is PN40, body material is WCB,Main diameterDN50, bypass diameter DN25, vertically mounted,Model: ZDL-PN40-C-50/25-V|
- According to the difference of inductive main flow, main valve disc check cone of automatic recirculation valve will automatically move to a certain position. At the same time the main valve disc drive bypass valve stem, transfer the movement of main valve disc to bypass, through control bypass valve disc position, change bypass throttling area, so as to control bypass flow. When main valve disc back into valve seat closed, all flow backflow through bypass. When mian valve disc to rise to top position, bypass is fully closed, all the flow of pump flow to process system. This valve set four functions in one body.
- Flow perception: automatic recirculation valve main valve disc can automatically perceive main flow of process system, thereby according to the flow to determine position of mian valve disc and bypass disc.
- Recirculation control: automatic recirculation valve can inhaled pump normal operation required minimum flow into storage device through bypass, so as to adjust pump H – Q characteristics, to realize recycling.
- Bypass multistage pressure reducing: bypass control system can reduced the backflow medium from high-pressure pump outlet to appropriate backflow to low-pressure storage device with low noise small wear.
- Check: automatic recirculation valve also has check valve effect, preventing the liquid backflow to pump body. Bypass non return function is standard.
- Special bypass size can be customized. The max flow rate of bypass is subject to the max Kv value.
Other bypass size can be made according to requirements, maximum bypass flow depends on maximum Kv value.
|Max main flow||m3/h||12||28||30||50||100||114||200||400||455||750||1250||1650|
|Max bypass Kv||Cv||1.6||2.9||2.9||3.7||6.8||6.8||12.3||12.3||21.7||31||51||86|
Note: Valve mian ouelet size depends on the outlet size of pump.
Main parts and out form dimension
Parts and materials
|1||Body||7||Stud bolt||13||O ring||19||Control head|
|2||Guide ring||8||Hex nut||14||Pin 1||20||Multi-hole
|3||Main valve disc||9||Guide screw
|15||Pin 2||21||Spring 2|
stud B type
|5||Spring 1||11||Turn arm||17||Hex nut||23||Bypass valve
|6||O ring||12||Control slide||18||Oring|
Dimension and weight
※Since product innovation and technical innovation or some special requirements, various valve connecting size may change, please contact Datian Valve technical department to get the latest product information. We can also produce according to your requirements.