ZDL series automatic recirculation valve

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.
  • tandard 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.


  • 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.