3、 Selection of pneumatic components
1. When selecting the pneumatic head, first determine whether it is a single acting pneumatic head or a double acting pneumatic head, and then select the pneumatic head that meets the output torque requirements according to the valve working conditions, air source pressure and other parameters. An example is given to illustrate the selection process of the pneumatic head: the pneumatic ball valve 16 14BS15J is selected, and the actual pressure is 19.5MPa. The selection of the pneumatic head is EMERSON, single acting, fault position closed, and the air source pressure is 0.55MPa. The data can be obtained by checking the Torque Table of Pneumatic Ball Valves, see Table 2. If the safety factor is 1.4, the torque values at each position of the valve are shown in Table 3. According to the EMERSON product sample, the pneumatic head model G7028-SR4-CW is selected. As can be seen from Table 3, all torque values are greater than the torque values at the corresponding position of the valve, meeting the requirements. Table 2 Torque Data of Pneumatic Ball Valve Intelligent Torque Calculation Calculated Torque under Full Pressure/N m Actual Pressure/MPa Calculated Torque under Actual Pressure/N m Caliber/in lb/Lb1415002100019.516058.82 Table 3 Torque Value Valve Position VBTOVRTOVETOVBTCVRTCVETC Actuator Position ABTOARTOETOABTCARTCAETC16 14BS15J224841349016863202361349020236G7028-SR4-CW429551855828233473214578214042 When selecting the solenoid valve, pay attention to whether the characteristic parameters of the solenoid valve meet the requirements, such as pressure range, flow medium, operating temperature, flow coefficient, voltage, explosion-proof requirements and other functions.

(1) During the development of ferrule connection in recent years in China, the principle of selecting the "ferrule connection" mode is that when the nut is tightened, the ferrule will be under pressure, causing the edge to bite into the outer wall of the pipe. The conical surface of the ferrule will be connected with the inner conical surface of the joint under pressure, thus preventing leakage. The reason why this pneumatic butterfly valve is adopted is mainly because of its strong connection force, wide application range and high pressure resistance.