The selection of diaphragm pump diameter and determination of the main basis of the valve's circulation capacity is Cv. In the instrument design and selection of various projects, the diaphragm pump is Cv calculated and the diaphragm pump design specification is provided. From the Cv of the diaphragm pump to the diameter of the valve, the following steps are generally required:

1. Determine the flow of computation. The existing production capacity, equipment load and the condition of the medium determine the Qmax and Qmin of the calculated flow.

2. Determination of pressure difference before and after the valve. Select S (drag coefficient) according to the selected valve flow characteristics and system characteristics, and then determine the differential pressure.

3. Calculate Cv. The Cmax and Cmin are obtained by selecting the appropriate formula and charts according to the medium.

4. Choose Cv. According to Cmax, >Cmax is selected in the selected product standard series and its closest to the level C.

5. The diaphragm pump opening check. General requirements at the time of maximum calculation flow opening ≯ 90%, the smallest calculation flow when opening ≮ 10%.

6. Actual adjustable ratio of diaphragm pump. General requirements are actually adjustable to 7.Determination of seat diameter and nominal diameter. After verification, according to C.