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When using a flow control valve (FCV) to regulate flow in the systemdownstream of a pump station there are negative pressures in many nodesor the model is unbalanced/unstable.Product: WaterGEMS V8iVersion: 08.11.03.017Area: Output/Results Presentation, Problem ID#: 67804, PROBLEMSOLVINGSee Also: FCV. Flow Control Valves, instability, negative pressures,unbalanced network
There could be multiple issues here:1) The FCV's could be limiting the demand to a number lower than thetotal of the fixed demands you have in your model. If you add up theflow settings for all the FCV's that are active in your model theyshould be equal to or greater than the total fixed demand on the nodesin your model.2) Sometimes if the FCV's are providing right around the same flow as isphyscially demanded from the model the calculation engine can havetrouble mathmatically converging. Slightly increasing the flow in theFCV's may help or if the demands in the model are actually pressuredependent demands then setting up a pressure dependent demand functionmight also help.If you still have issues after reading this and examining the data inputfor you model please contact technical support for more help.