Checks the pump performance by determining head
Well one could carry out a "Wire to Water" test but you should realise that running pumps in parrellel would not give you a proper reading for each pump as although the TDH would remain relaitivly the same, the flow does not double as most people seem to think. Another problem would be if the pumps in parrellel do not have the same duty.I wish you luck in your struggle and hopfully some bright spark will guide us all to the path of enlightenment !
The no-flow test I assume checks the pump performance by determining head at shutoff conditions. I think this no-flow test would only be valuable if you can manipulate your system to isolate the discharge of the pump under test from other pumps (and still able to measure discharge pressure). The test would be limited if you tried to conduct it on multiple pumps all feeding in parallel to a shutoff header, since the performance of a weak pump would be masked by the performance of a strong pump.If you have the ability to measure the individual flow (and dp and fluid temperature) on each pump, then you can locate the performance of that pump on its own curve regardless of what other pumps are in operation. Otherwise (if no individual Split case pumps flow info) you'll have to make some assumptions regarding the sharing of load which will decrease the ability to accurately evaluate each pump.Note that flow measurements can often be made with temporary ultrasonic info outside of the pipe.As it stands your question is pretty wide open. Can you clarify what you are trying to accomplish?
I would do the following for check of efficiency:1)with pumps running measure flow and outlet pressure where pump outlets combine. This will probably be the difficult bit if you dont have instrumentation!2)Using SI units multipy pressure by flow i.em3/s * Pa = Watts (work being done)NB 1Pa= 1N/m2, also 1Bar = 1 x 10^5 PaRead off the power consumption printed on pump motors.Calculated value for work should be about 50% of the motor power consumption allowing for inefficiency of the motors, the pumps and any losses in the pipes / manifolds. If your in this ballpark all is well!
2011-08-30
