The 8200 electric pneumatic valve positioner is mainly used to improve the linearity of the regulating valve, accelerate the valve action speed, overcome the unbalanced force of the regulating valve core, and achieve split range control.

Technical indicators
The characteristics are as follows
Compact structure, light weight, explosion-proof components composed of torque motor and junction box
Due to the use of standardized structural components, it is easy to maintain. And all screws are made of stainless steel
Zero position and travel are easy to adjust;  
The back and side of the locator can be installed on the actuator;  
Easy to switch from automatic operation to manual operation.  

structural principle
Structure: The locator consists of a torque motor, armature, spring, zero adjustment spring, nozzle baffle, amplifier, automatic/manual switching mechanism, feedback spring, feedback rod, etc.
Principle: When the signal current is input to the torque motor, the armature rotates clockwise with the spring as the fulcrum. The baffle is close to the nozzle, which increases the pressure in the back pressure chamber of the nozzle. The diaphragm pushes the pilot valve, and the gas source pressure becomes the output pressure, which enters the actuator. The push rod of the actuator moves downwards and drives the feedback rod, feedback spring, etc. When the force generated by the torque motor is balanced with the feedback spring tension, a certain signal current corresponds to a certain position of the push rod.
Input signal: 4-20mA DC (with additional 4-12 or 12-20mA DC split range control signals)
Input impedance: 250 Ω
Gas source pressure: 0.14-0.7MPa
Explosion proof type: Explosion proof type (d Ⅱ BT4), Intrinsic safety type (ia Ⅱ CT4)
Basic error: ± 1.0% FS (± 2.5% FS for cam type), FS is the full range value (± 2.5% FS for cam type)
Return difference: 1.0% FS
Dead zone: 0.2% FS
Gas consumption: 500L/h (when the gas source pressure is 0.14MPa under standard conditions)
Weight: 2.5kg