The main accessories of the pneumatic control valve include: valve positioner, solenoid valve, valve position feedback, air filter pressure reducing valve, retaining valve, pneumatic relay, etc. The selection principles of the main accessories are described below:
1、 Valve positioner The valve positioner is the main accessory of the pneumatic actuator. It is used together with the pneumatic actuator to improve the position accuracy of the valve, overcome the influence of the friction force of the valve stem and the unbalanced force of the medium, so as to ensure the correct positioning of the valve according to the signal from the regulator. The valve positioner is used to convert the 4-20mA control signal into the air pressure signal to the pneumatic actuator, so as to drive the regulating valve for regulating function. Valve positioners are divided into mechanical positioners and intelligent positioners. The intelligent positioner has higher control accuracy than the mechanical positioner and lower air consumption. In addition, it can also be equipped with the HART protocol function.

This is a popular means of control in the world, and it is also the general trend of the domestic electric ball valve in the future. Enterprise operators need to release their own ideas on this issue, completely break the geographical restrictions and boundaries according to the requirements of the department, and break the traditional industrial division of labor mode. Only when there are signs of joint cooperation between enterprises, they should boldly try, Try to use three to five years to build a large enterprise group, and try to make the sales amount of the enterprise group reach 500 million yuan or even 1 billion yuan.