How to add Xi, Xf, or Kv values to a FCV

Hello,

FCVs in WaterGEMS and WaterCAD can enter a minor loss coefficient (C) or a discharge coefficient (Kv). To select which you enter by changing the property field "Valve Coefficient Type" between minor loss or discharge coefficient. However, these values are only used when the valve is fully open (when it has an initial or calculated status of Inactive).

With an FCV, a headloss is applied at the valve as a way of limiting the flow. There is no table for the valve opening versus the discharge coefficient. The program applies this directly for you. 

If this isn't useful, some information on the coefficients involved will be useful.

Regards,

Scott

It sounds as if what you want to model is not a FCV but a Throttling Control Valve (TCV). See the help for that type of element.

You can enter the valve patterns under Components > Patterns and the characteristics under Engineering Libraries > Valve Characteristics Library.

I am not familiar with the coefficients you refer to, but as Scott said, we support Discharge Coefficient and Headloss Coefficient as methods for entering headloss. I agree with Tom about the use of the TCV element for this. Set the "Coefficient type" to "Valve Characteristics Curve", then select "user defined" as the "valve type", then define your table of relative closure versus relative discharge coefficient (relative to the "fully open discharge coefficient".)

The definition of the Discharge Coefficient we use is explained here: What is the "Discharge Coefficient"?

You can also read more about the use of the valve type field (for relating percent closed to discharge coefficient) here: Valve Type field assumptions and use with a TCV

You can read more about the configuration of TCV Initial Settings here: How are headlosses determined for TCV's with the different initial status settings?

The "Headloss coefficient" method uses the standard "K" in the standard headloss equation Headloss=K*V^2/2g

As Scott said, if this does not match what you need, please elaborate on what this valve does, and what these coefficients represent.