Selection of control valves and pump head
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If a pump is used to transfer a fluid from container A to device B, and there is a automatically controlled regulating valve in this pipeline, then when determining the head required for this pump, in addition to considering the static pressure in container A, the operating pressure required by device B, and the pipeline losses, must the pressure difference caused by this automatically controlled regulating valve also be taken into account (that is, the pressure difference specified by the process instrumentation team)?
It should be like that, but I’m not sure how to calculate the pressure drop of the control valve
Generally, a control valve has a significant regulating effect only when its pressure drop accounts for more than 30% of the total pipeline pressure drop.
That’s correct; therefore, during the stage when the valve has not yet been selected, an pressure drop of 30% higher than the total pressure drop should be estimated as the pressure drop for the control valve.
When calculating the pressure drop in the pipeline, the pressure drop across the control valve is taken as 0.05–0.07 MPa(G); generally, 0.07 MPa(G) is used for calculations.