High reputation Ss Lug Butterfly Valve - ZDL Series Automatic recirculation control valve – Convista

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ZDL series Auromatic recirculation valve is a kind of pump prtectiong device. It automatic protects centrifugal pump when pump body occur cavitation damage or unstable (especially conveying hot water at low load operation). 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 recirculation. 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-spped flow medium, and precent cavitation.

Characteristics

• 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 fuction, 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 DN2 to DN500.

• Can select manual bypass operation function, used in fault.

Size and pressure range

Valve body type: Three-way forged body.

Nominal diameter: NPS1″-20″ (DN25, 32, 40, 50, 65, 80, 100, 200, 250, 300, 350, 400, 450, 500)

Nominal pressure: CL150#-600# (PN16, 25, 40, 64, 100)

End connection type: Flange, FF, RF, RTJ, BW, SW etc.

Working principle

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 main 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 recircution valve main valve disc can automatically perceive main flow of process system, thereby according to the flow to determine position of main 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 charateristics, 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 optional.
• Special bypass size can be customized. The max flow rate of bypass is subject to the max Kv value.

Major parts material