Therefore, if the material of the electric butterfly valve declines, it will certainly not meet the best requirements when using the product. First of all, it will have a great decline in sealing. Now more users use this product because of its good performance in sealing, However, if the manufacturer does not have good material advantages during production, it can't be allowed to have requirements on the overall tightness of the product.

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.