Well-designed Flow Control Valve Bs - ZDM Series Automatic recirculation control valve – Convista

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ZDM series Automatic recirculation valve is a kind of pump protection device. It automatic protects centrifugal pump when pump body occur cavitation damageor 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.

ZDM series is suitable for bypass with high pressure differential, maximum pressure differential is 30MPa, and specific choice is determined by factory. Multistage decompression type M type bypass can eliminate noise made by high-speed flow medium, prevent damage of cavitation erosion and braising to valve components.

Characteristics

• Prevent cavitation multistage decompression bypass, reducing velocity, suitable for high pressure conditions.

• Forged valve body, or you can choose carbon steel or stainless steel material, etc.

• Standard bypass non-return function, maximum working pressure differential is 30MPa.

• Pressure grade from PN16 to PN420, diameter from DN2 to DN500.

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

Size and pressure range

Valve body type: Three-way forged valve
Nominal diameter: NPS1″-20″ (DN25, 32, 40, 50, 65, 80, 100, 200, 250, 300, 350, 400, 450, 500)
Nominal pressure: CL150#-2500# (PN16, 25, 40, 64, 100, 160, 250, 420)
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 standard.
• Special bypass size can be customized. The max flow rate of bypass is subject to the max Kv value.

Major parts material