Efficiency curve pumps in parallel
Efficiency curve pumps in parallel
(OP)
Hi Friends
Please how to draw the efficiency curve of different pumps in parallel having the efficiency curve of each one.
I m not hydraulic engineer may be the question is simple, but excuse..
Thank you very very much in advance.
Please how to draw the efficiency curve of different pumps in parallel having the efficiency curve of each one.
I m not hydraulic engineer may be the question is simple, but excuse..
Thank you very very much in advance.





RE: Efficiency curve pumps in parallel
You need to develop a system curve and then see where the joint flow curve meets it. If you have pumps with different curves this is not easy or straightforward, but can be done with a bit of iteration.
If you have the pump curves and can post them that will explain a bit more, plus you need a bit more description here.
Remember - More details = better answers
Also: If you get a response it's polite to respond to it.
RE: Efficiency curve pumps in parallel
Thank you very much for this answer. What I want exactly is to estimate a general efficiency of the two pumps in parallel. I don't have curve here, I will plot them ASAP to further explain the problem.
Thanks a lot
RE: Efficiency curve pumps in parallel
Then overlay the system curve with two pumps operating
To find the pump efficiency, go back to performance curve of each pump using the operating points obtained on your graph.
RE: Efficiency curve pumps in parallel
What if the two pumps are of different performance curves?
Many thanks
RE: Efficiency curve pumps in parallel
RE: Efficiency curve pumps in parallel
many thanks again dear friend
RE: Efficiency curve pumps in parallel
That is a LOT of pumps in parallel, I can only image that your system curve is not a fixed line, but some sort of thing which has multiple flow paths or users as well.
at those flow rates I'm guessing this is some sort of water distribution system?
Remember - More details = better answers
Also: If you get a response it's polite to respond to it.
RE: Efficiency curve pumps in parallel
will plot the curves once back to my office (don't have them here :) ).
Many thanks friends for your help.
RE: Efficiency curve pumps in parallel
Many of these sorts of systems work on maintaining pressure at some point (discharge or somewhere in the feed system) within a range of pressure and then bring on or drop off pumps to maintain the pressure within that pressure range.
only by looking at the head across the pump can you estimate flow in each pump and hence the efficiency at that flow rate.
Only by looking at the shape of the head curves and what your operating range is can you start to think about what is happenng.
Your pump curves at the operating range will need to have a reasonable slope to them otherwise you could be getting wildly different flows in each pump, even if they are "identical".
Remember - More details = better answers
Also: If you get a response it's polite to respond to it.
RE: Efficiency curve pumps in parallel
In actual practice, you are essentially pumping into a constant backpressure. To arrive at your pump efficiency, just take range of discharge pressures at the pump discharge, and read the pump efficiency of each pump off of the individual pump curves.
I suspect that backpressure that you are pumping against is in a range of maybe 10-15 psi. It is likely that the pumps were selected to operate in that sweet spot.
RE: Efficiency curve pumps in parallel
It is a capital mistake to theorise before one has data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts. (Sherlock Holmes - A Scandal in Bohemia.)
RE: Efficiency curve pumps in parallel
RE: Efficiency curve pumps in parallel