Hello Ronni

I read the email several times and still I am in doubt about the request from NK.

We don’t use the coefficient of discharge to calculate the valves (pressure and vacuum) capacity. We use the specific design type of valve with incremented set pressure or vacuum and we establish a flow capacity curve.

The flow curves are in reality the valve profile for flow resistance.

The flow resistance is a function of the cross section, so the flow capacity shall be measured where lift of the seat disk is just sufficient for the nozzle to control the flow or where the sear disk lift was a fixed stop.This means that, in the case of the pressure units, only when the valve is in full open position and we get a stable flow. But for the vacuum units the lift is incremented with the flow, so we don’t have a fixed flow resistance.

For the vacuum units you have the followed flow resistance:

Has you can see there is no fixed value.

The flow curves are the more correct method to calculate the pressure drop across the valves for a specific capacity, and from the flow curves it’s possible to calculate the flow resistance.Below is a flow curve with the acquire data and the fitted data.

NK question doesn’t make sense, since I believe they received the flow curves and the test records for each valve.

I can give you the flow resistance for the ECO but from the setting point up, since are when the valve will be complete full open and where the coefficient starts to stabilize.

I hope this can clarify the class.