what is Pumps process Minimum Flow?
what is Pumps process Minimum Flow?
(OP)
Please explain me pump minimum flow should be less than process minimum flow .If it get more than process minimum flow how to control that flow. Also please explain me why the shut off head should be 5 % in normal operation & 10 % for parallel operation ?





RE: what is Pumps process Minimum Flow?
More flow is controlled either by speed control of the pump (VSD) or control valve downstream of the pump throttling the pump and reducing flow
Normally API 610 pumps require no more than 10% head rise from duty point to shut off head. Don't know why this is 5%
Parallel operation should be no different to "normal"
This is to stop pressure rising too far on no flow / start-up and creates a steady head / pressure during operation.
My motto: Learn something new every day
Also: There's usually a good reason why everyone does it that way
RE: what is Pumps process Minimum Flow?
RE: what is Pumps process Minimum Flow?
RE: what is Pumps process Minimum Flow?
Why 10% (and not say 15%) - don't know, but is a measure of a higher quality centrifugal pump and has been shown over time to be a number that works well and doesn't cuase any substantial issues in terms of overpresusre of piping in the event of no flow.
Dubmac is exactly correct - paralell pumping of even "identical" pumps are rarely equal, but the steeper the curve, the more likley it is that the share of flow between towo or more pumps is more evenly split
My motto: Learn something new every day
Also: There's usually a good reason why everyone does it that way
RE: what is Pumps process Minimum Flow?
The old equation for Temperature rise in a pump (don't know why a new one would be any better) is:
Temp Rise, DegF= (TDH,ft./778) * ((1/Efficiency at point considered) - 1)
If a manufacturer of a certain pump says the max permissible temp rise is 20 degrees, then you can backcalculate your minimum flow using the performance curve.
RE: what is Pumps process Minimum Flow?