Minimum flow rate of centrifugal pump
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How is the minimum flow rate value of a centrifugal pump calculated? What determines it?
I only know 30%, I don’t know how to calculate it
Generally, 20% to 30% of the pump’s maximum flow rate is used as the minimum flow rate. The calculation method is quite complex, and it varies depending on the purpose for which the minimum flow rate is required~~
It is also possible to conduct a practical test: adjust the valve to the desired flow rate and measure the temperature of the pump body for 120 minutes to see how much the temperature rises! As long as there’s no significant growth, that’s fine!
These large pumps and small pumps are not the same; the exact values are determined through experiments, while what people use are merely empirical values. There’s no point in delving deeper into this, as it’s likely that your pump will never reach such levels. If you use it frequently, it means you’ve chosen an inappropriate pump for the task
The minimum flow rate of a centrifugal pump refers to the lowest flow limit required to maintain its normal and continuous operation； If the pump operates below this limit, it may cause damage to the pump. This value is provided by the manufacturer; for details, refer to the performance curve of the centrifugal pump. Since a centrifugal pump converts only a portion of the power supplied by the motor into useful energy during operation, the remaining part is used to overcome frictional heat generation and mechanical losses, that is, it is converted into heat energy. When the flow rate of the centrifugal pump drops to a certain level, its efficiency becomes extremely low; most of the power output by the motor is converted into heat energy, and this does not result in an increase in the temperature of the fluid or the pump itself. When this thermal balance is disrupted, it leads to issues such as cavitation due to vaporization, damage to bearings and mechanical seals, excessive vibration of the pump, as well as deterioration of the flushing and lubricating fluids.
It’s not calculated; it’s the actual value measured by the pump
It is generally set at 20% to 30% of the pump’s maximum flow rate; no calculation is done for this value.
Calculate the minimum flow rate range of the pump based on the export stress values
This can’t be counted, right? Adjust the outlet valve by yourself and check the temperature of the pump body