How to select the electric pneumatic - valve product

1. Electric pneumatic control valve selection of main control parameters are designed for the nominal diameter and nominal pressure, allowed temperature range, flow coefficient, etc. 2. Open for traffic and high proportional relationship of rigorous situation, should choose special pneumatic control valve. Ball valve and butterfly valve general coarse adjustment can be chosen. 3. Examination is the sealing performance of the valve valve is one of the main indicators of quality. Valve sealing performance mainly includes two aspects, namely, internal leakage and leakage. Leakage refers to between the seat and closed on the degree of sealing medium to achieve. Leakage is refers to the leak of stem packing place, in the mouth of the gasket leaking caused by casting defects of leaking, and the valve body. No leakage is allowed. 4. Pneumatic - valve ideal flow characteristic are quick opening, parabolic, linear, such as percentage of the four, to choose appropriate flow characteristics according to actual work flow characteristic of pneumatic control valve. The principle of selecting flow characteristics are shown in table 1. Table 1 according to select the valve pipe actual working characteristics of the selected flow characteristic S = 1. 0 ~ 0. Six straight line S = 0. 6 ~ 0. 3 equal percentage equal percentage S < 0. Three straight percentage equal percentage control situation, control inappropriate note: S = pneumatic control valve fully open pressure loss/pneumatic control valve series branch total pressure loss. In order to avoid excessive water velocity of flow through valve and try to save the water pump power consumption, appropriate S&le the working state of the valve; 0. 7. 5. The selection of pneumatic control valve nominal diameter should be determined according to the required valve flow capacity. Pneumatic control valve nominal diameter should not be too big or too small. Increase the project cost is too big, and the valve is in low percentage range, accuracy is reduced, the control performance. Is too small, increase system resistance, can appear even open valve 100%, capacity requirements set by the system still cannot achieve.