1. Determination of calculated flow. The existing production capacity, equipment load and medium conditions determine the Qmax and qmin of the calculated flow.

2. Determination of the pressure difference before and after the electric regulating valve. Select s (resistance coefficient) according to the selected valve flow characteristics and system characteristics, and then determine the calculated differential pressure.

3. Calculate cv. According to the adjusted medium, select the appropriate calculation formula and chart to obtain Cmax and Cmin.

4. Select cv. According to Cmax, select the level C that is > Cmax and closest to it in the selected product standard series.

5. Checking calculation of opening of electric control valve. Generally, it is required that the opening at the maximum calculated flow is more than 90%, and the opening at the minimum calculated flow is less than 10%.

6. Checking calculation of actual adjustable ratio of electric control valve- Generally, the actual adjustable ratio is required to be 10.