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Unusual Flow Results

I'm getting some unusual results and am unable to find a solution. I'm trying to better calibrate our model near an area where 2 pressure zones meet.

I've performed a fire flow analysis and tried to confirm the pressures and flow in that area.  A flow test was performed at hydrant H-1782. Just north of this test location, we have a control valve that stays closed if our north system has less pressure than our south system.(they differ by 20 psi because of tank elevations).  I've tried modeling this valve as a PRV.  We also have some isolation valves in the area and have ran the model with the isolation valves closed and get the same results.

The model predicted the following:

Static: 54.4 psi

Residual 23.3 psi

Flow: 591 gpm


Actual flow test data:

Static: 64 psi

Residual 38 psi

Flow: 1950 gpm

This tells me that the model is predicting to much head loss.  I've confirmed that the C-factors are correct, tried zeroing out the demands south of the test location thinking the demands might be too large, and checked for closed valves.  None of this seemed to help the situation.

The piping feeding this area has a 6" & 10" feeding into an 8" main which eventually increases to a 12" main.(Don't ask why)


I've attached the model for your convenience.  Any help/ideas is greatly appreciated.

2013 Water Model.zip