Dear all,
As shown in the attached file, consider 2 pump station in series, the first pump station consists of 3 parallel pumps (each pump works at BEP with 10 m3/h capacity and 5 bar pressure) and the second one consists of 6 parallel pumps (each pump works at BEP with 5 m3/h capacity and 20 bar pressure). I need to know what happens if one of the first station pumps turned off? Does the flow suction of the second pump station force the remained 2 pumps of first station to operate at a rated flow (more than 10 m3/h capacity and less than 5 bar pressure)? What happens for the second station at this condition? Do the second station pumps operate at a rated head (less than 5 m3/h flow and more than 20 bar pressure)?
Thanks in advance.
The operating point of a system will always be at the intersection of the pump curve and the system curve. When you have pumps in parallel you can create an equivalent pump curve by adding the flow rates at a given pressure rise (curve will stretch in the x direction). When you have pumps in series you can create the equivalent pump curve by adding the pressure rise at any given flow rate (curve will stretch in the y direction). If you turn one pump off the equivalent pump curve will change and will intersect your system curve at a new point.
I could help you but I have some questions. Should I suppose that the stations are pumping water or any particular substance? Should I suppose that the total pumps are centrifugal pumps? I would like you answer these question for giving you a hand. I would like to help, it's a interesting question. Thanks for sharing it.
Dear Julian
Thanks for your attention. All the pumps are centrifugal and they pump water. However, as the attached file shows, contrary to the first station, the second station pumps don't work in parallel. they pump water to the individual consumers, but flow and dP of the pumps in the second station is similar.
best regards
Hi Hossein Karimi,
if one pump of the first station gets turned off, the mass flow rate and pressure is decreased. This means that the second station goes to deliver less than 5 and 20 bar. In general, you have to take into account that if one pump is turned off, the remaining pumps have to deal with the system curve. In other words, the remaining pumps have to cover the losses and static pressure of the system. Finally, I wonder that whether one pump gets turned off, the discharge valve is closed immediately, for this example. I hope this answer reaches your expectations. Any further question, feel free to ask.
Thanks and best regards
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