It mainly explains the additional code of pneumatic ball valve, pneumatic ball valve code, driving mode, connection form, structural form, sealing material, pressure rating, and valve body material. The preparation method of pneumatic ball valve model and the comparison description of pneumatic ball valve model code: pneumatic ball valve function code: V means the valve core has V-shaped structure, D means low temperature, B means insulation, P means eccentric structure U, S and DY mostly refer to top mounted type; Pneumatic ball valve drive code: 2 indicates electro-hydraulic, 3 indicates turbine, 6 indicates pneumatic, 7 indicates hydraulic, 9 indicates electric and manual without code;

The output impedance of the electrode of the electromagnetic flowmeter determines the input impedance required by the converter, and the output impedance of the electrode can be considered as dominated by the fluid conductivity and electrode size.
In theoretical analysis, the electrode is taken as a point electrode, and the size can be ignored. In fact, the electrode has a certain size. When the circular plate electrode with diameter d contacts the semi infinite broadening fluid with conductivity K, its broadening resistance is 1/2Kd. Therefore, if the pipe diameter D ＞＞ d, the output impedance of the electrode is the sum of the two broadening resistance, that is, 1/Kd.