ProcessEngCAN
Chemical
- Mar 18, 2013
- 1
Dear experts,
Need your help..
I,m specifying a centrifugal pump and control valve pressure drop to instrument engineer for control valve sizing.
The question is, I have a normal flow and rated flow. The control valve will be fully open during rated flow, the control valve will be throttled during normal flow to ride the pump back on the curve. For instance I had start with a 5 psi pressure drop in rated flow across a control valve. Then I adjusted my discharge pressure in normal and rated flow and made it equal. In doing so, I,ve calculated the pressure drop during normal flow which is of course more than the pressure drop in rated flow, this is to account for less dynamic losses which I incurred in normal flow. Now I get some 10 psid delta p across control v in normal flow and the diff head is same in normal and rated flow.
Is this a valid assumption to make the discharge pressure same in normal and rated flow. Since the control valve will close more in normal flow and will give the same pressure as if when the pump would be running in rated low with less resistance with control valve fully open.
Any suggestion And comments are greatly appreciated.
ProcessEngCAN
Need your help..
I,m specifying a centrifugal pump and control valve pressure drop to instrument engineer for control valve sizing.
The question is, I have a normal flow and rated flow. The control valve will be fully open during rated flow, the control valve will be throttled during normal flow to ride the pump back on the curve. For instance I had start with a 5 psi pressure drop in rated flow across a control valve. Then I adjusted my discharge pressure in normal and rated flow and made it equal. In doing so, I,ve calculated the pressure drop during normal flow which is of course more than the pressure drop in rated flow, this is to account for less dynamic losses which I incurred in normal flow. Now I get some 10 psid delta p across control v in normal flow and the diff head is same in normal and rated flow.
Is this a valid assumption to make the discharge pressure same in normal and rated flow. Since the control valve will close more in normal flow and will give the same pressure as if when the pump would be running in rated low with less resistance with control valve fully open.
Any suggestion And comments are greatly appreciated.
ProcessEngCAN