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Deriving Pump Flow Equation from Pool to Pool head as variable

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Merc115

Civil/Environmental
Joined
Aug 3, 2006
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2
Location
US
I manage a SCADA system and we just put a new pump station online and in the programming of an older station the flow from each pump is calculated as shown below using a 5th order equation with the pool to pool head as the variable :

10 POOL.HEAD=DISCHARG.LVL-CANAL.LVL
20 FLOW2.CALC=(.05115121*POOL.HEAD**5)+(-3.536126*POOL.HEAD**4)+(92.40789*@
POOL.HEAD**3)+(-1136.182*POOL.HEAD**2)+(6475.484*POOL.HEAD)+@
(-12219.11)
30 FLOW1.CALC=(.00000275528*POOL.HEAD**5)+(-.00006510103*POOL.HEAD**4)+@
(-.001186331*POOL.HEAD**3)+(-.07603356*POOL.HEAD**2)+(-1.267723*@
POOL.HEAD)+(337.3005)

Does anyone have any idea on how the flow1.calc and flow2.calc equations were derived?

Thanks!

 
nope!

but a swag is that the original pump mfg certified(?)curves were used to create the equations between min/max pump flows; assuming some impeller diameter and constant speed. determine head, thus imply flow through the pumps.

a thought, motor current is another valuable source for balancing pump loads for identical pumps/motors & equivalent loss in piping system.

find original mfg pump curves and test the equations.

good luck!
-pmover
 
I agree with pmover. Find the performance curves then fit that polynomial to the characteristic curve. You could do it pretty easily with least squares method or even have excel do it for you for that matter. My guess is the two equations correspond to two different desired flow rates.
 
I just did the same thing 2 days ago.

The constants were derived from each pump's characteristic curve... turned around, ie plotted with Flow vs Head, rather than the customary manufacturer's curve plot of Head vs Flow.

Each pump has a different curve, which is why the coefficients vary.

That's it.

Going the Big Inch! [worm]
 
Thanks for the QUICK response!

Now I have a clear idea of waht to do.

 
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