Background info (including Jesse Dringoli's response) can be found here.

The Flow Control Valve (FCV) calculations in WaterGEMS currently allows the calculated Cv value to exceed the fully open Cv value. The link to the Forum post above includes more detail & a simple example model file.

I noticed that in a falling-head tank example (valve being used to maintain constant flow out of a tank), the FCV continued to maintain the specified flowrate even when this required a Cv value > the fully open CV value for the valve. When this happens, the model returns a Message ID 40023 "headloss is lower than it would be...".

The warning message is helpful, but it seems more hydraulically correct to just allow the valve to fully open, use the fully open Cv value to compute the flow rate, and return a 40009 message "cannot deliver flow."

Jesse suggested that this might be handled with a user setting (user can determine the behavior).

Thanks,
Bryan