How to determine the head of a centrifugal pump
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In the hydraulic calculations of centrifugal pumps, in addition to determining NPSHA, it is also necessary to calculate the pump’s head value. The usual method of calculation is to add a 10% margin to the pressure difference between the pump’s inlet and outlet, and the resulting value is used as the head. So for cases with a low voltage difference, a 10% margin might be too small; should a lower limit be considered? By the way, 10% is generally considered, but the guidance for a project I encountered previously suggested using a lower limit of 0.05 MPa, which is approximately equivalent to a head of 5 meters. Is this reasonable? I earnestly request the experts' guidance; thank you.
Whether a 5-meter head is appropriate depends on the density of the medium; if it has a low density, then it should be fine
A head of 5m is lower, so multiplying by a 1.2 coefficient ensures safety.
Head * 1.2 is used to calculate the pump’s shutoff pressure. Of course, the larger the coefficient, the more secure it is, but are there any standards, guidelines, or manuals that set a minimum value for it?
LZ can take a look at the following standard: HG-T 20570.5-95 Calculation of the system characteristics of pumps and determination of the relative installation height of equipment.
It needs to be calculated carefully, using Bernoulli’s equation from principles of chemical engineering to do the proper calculation