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.