Is it possible to reduce both the inlet and outlet sizes of a centrifugal pump at the same time?
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There is an HTH25-200 centrifugal pump on site; the pump’s inlet and outlet dimensions are 40/25, its head is 30 m, its flow rate is 4.1 m3/h, and its rotation speed is 2950 r/min. The medium density is 900, and it isn’t very sticky. The process now has a requirement: add a pipeline at zero hour to output through this pump. The current design for the process is to change the inlet and outlet dimensions to 25/20, with a flow rate of around 1 m3. I was wondering if this is feasible? Also, what is the minimum flow rate of a pump, usually as a percentage of its rated flow rate? Thank you all very much.
This post was last edited by cnoocjeff on 2015-10-13 at 12:38. It wasn’t changed like that, was it? The minimum continuous flow rate must be determined by consulting the pump manufacturer; moreover, if the properties of the fluid change, recalculation is required. (Based on personal experience, it’s fine for this pump to handle 1 cubic meter of fluid – the issue lies in whether the piping setup is suitable for such conditions.) You can buy a pneumatic diaphragm pump for temporary use; it’s portable as well, and its flow rate and head should meet your requirements
The minimum flow rate for long-term operation is 30%, and 20% for short periods.
To make things easier, I’ll go talk to him tomorrow
It’s simpler to just use an inverter
When changing the inlet and outlet pipe diameters of the pump in this way, the issue of pump cavitation must be taken into account.
Changing the pump inlet and outlet pipe diameters like this should also be fine
1. The issue of pipe diameter: if the diameter of the pipeline is smaller than that of the pump’s inlet and outlet, gas entrapment is likely to occur； 2. Regarding the minimum flow rate issue, the pump’s minimum flow rate is generally around 35% of the flow rate at its optimal efficiency point. As for the rated flow rate, no definite conclusion can be drawn because its relative position with respect to the optimal efficiency point is not clear. It is necessary to check the performance curve of the pump; or, as you suggested, run it at the specified flow rate for about 2 hours to verify whether there is cavitation, temperature rise, or vibration. If there are no problems with any of these, then generally nothing is wrong.
Changing the diameter doesn’t seem to be useful; narrowing the inlet increases the likelihood of cavitation. Whether the pump outlet should have a certain flow rate or not only results in higher outlet resistance and faster flow velocity. I don’t think there’s much of a problem with the small pump; even at 1 cubic meter, you still get 25%! ! It depends on the actual situation! ! Personal opinion
Add a return pipe to the inlet at the outlet, and then use the return pipe to control the outlet flow.