Should the inlet or outlet valve be adjusted?
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Double-suction pump, model 200S-63, with a head of 62.5 meters and a flow rate of 288 cubic meters per hour. Manual rubber-lined double-seal gate valve, model Z42J10C, with specifications of DN200mm and a working pressure of PN1.0MPa. There is one gate valve at each inlet and outlet of the double-suction pump; both valves are of the same model. The normal flow rate is sufficient, but if it is necessary to reduce the flow rate, should the throttle be adjusted at the inlet or at the outlet? I searched on Baidu; it seems that the export setting should be used, but my colleagues all say that the import setting is what’s needed. What do you think – should we use the import or export setting? What is being adjusted currently is the inlet throttle, with an opening of about one-half.
This post was last edited by CHANGBAISHI on 2020-9-26 at 15:44. The adjustment of the centrifugal pump involves ensuring that, with the inlet valve fully open, the outlet pressure is met while referring to the motor’s rated current, which must not exceed the specified parameters. Gradually open the outlet valve. Once the current reaches the upper limit of the rated range, it indicates that the pump is operating at full load. Note: Throttle = valve. It is recommended that the terminology for equipment be standardized. If you are interested in chemical engineering and it is useful for your work, I recommend the book \"Principles of Chemical Engineering\", which serves as a reference guide for those working in chemical engineering. It can solve other similar on-site problems. For reference.
The outlet must be adjusted; adjusting the inlet can cause turbulence, leading to vibration of the pump or cavitation. Globe valves should be used for the outlet, as gate valves are prone to cavitation, which results in poor sealing
The flow rate of the pump is regulated by the opening degree of the outlet valve rather than the inlet
Adjust the outlet valve; closing the inlet valve too much can cause the pump to become vacuumed
In liquid centrifugal pumps, the load is regulated using the outlet valve; closing the outlet valve completely results in the lowest load, but this can cause the pump’s temperature to rise over time. Gas centrifugal pumps (centrifugal compressors, fans) ensure that the minimum load is maintained at startup by reducing the inlet flow and allowing the exhaust gas to flow into the atmosphere or be recirculated. After startup, referring to the rated current value, the suction valve is gradually opened until the current reaches the specified level; the pressure is increased using the outlet valve or return valve, and then the fluid is gradually supplied to the user. This must be controlled in this way due to the requirements of the medium’s properties.
It is generally not recommended to adjust the inlet valve of a pump; usually, the inlet valve should be kept fully open while the outlet valve is adjusted, as this helps to prevent cavitation damage to the pump
Keep the inlet fully open, and adjust the pump operation parameters at the outlet