WaterGEMS Darwin Calibrator miscalculating observed HGL

Question

I am using Darwin Calibrator and am noticing that some of the calculated observed HGL values vary significantly from the true value. For example, I have a node with an elevation of 554.19 with an observed pressure input of 85 psi and Darwin is showing the observed HGL as 749.86 in the results comparison when real value should be 2 feet higher...

Sushma Choure · Answer

Hello Ken, 
 Please check following, 
 How do I match the results I am getting from Darwin Calibrator in my model? 
 If this does not help you then please provide your model files for our review and also provide specific elements to look for. 
 Sharing model files

Scott Kampa · Answer

Hello Ken, 
 When I run the snapshot and export the solution to a new scenario, I am getting a red user notification related to a PSV in the model. This same user notification occurs with the scenario "Calibration - Static Nov 26 2018." 
 This appears to be related to several valves (FCV, PRV, and PSV) with initial status that are set to Active with initial values for flow (for the FCV) or pressure (for the other valves) that are set to zero. Usually the initial values for valves will be a non-zero number when the status is active. I would review this information to make sure it is correct. 
 If the valves should be fully open, I would change the initial status to "Inactive." If there should be no flow through these, I would set the initial status to "Closed." 
 Otherwise, I would make sure that the representative scenario you are using in Darwin Calibrator will compute without seeing a red user notification. 
 Regards, 
 Scott

Sushma Choure · Answer

Hello Ken, 
 We did calculations for observed HGL values again entered observed pressure and below are results in Calibrator, we didnt find much difference in the results though. 
 
 Please correct me, if there is any confusion in our understanding.

Scott Kampa · Answer

Hello Ken, 
 We took a look at the numbers. For J-12055 - Static 6, I get a value of about 750.25 ft using: (85psi * 2.30666)+554.19=750.25 ft. This is within about 0.4 feet of the value reported in Darwin Calibrator. 
 There may be some additional rounding in the conversion. In the actual observed data recorded in the field, there may be some precision error (for instance, the pressure may have been a little over or under exactly 85 psi). There could be some impact on the density of the water based on the water temperature, that would make an exact conversion less accurate. 
 In all, the values are not exact, but they are fairly close. Including possible rounding and precision errors, this may be within a reasonable accuracy. 
 Regards, 
 Scott