Valve Positioner
Positioner is installed on control valve in order to adjust its opening and closing in a span of 0 to 100 percent. Positioner is a interface between valve and control system and acts as a mechanical stabilizer and pneumatic buffer. Controller send a 3 to 15 psi (or 4 to 20 mA) pneumatic command. This command passes a pneumatic regulator(near valve) and apply to a positioner. Positioner delivers the same input pressure as output pressure to the valve.
There are two models of positioners; positioner with pneumatic input of 3 to 15 psi and positioner with input of 4 to 20 mA.
Because of their precision, positioners are best choice for control systems.
Typically, valve positioners are installed on the bottom part of pneumatic actuators in linear control valves. In rotary control valves however, they are installed near the end of the shaft.
8 Reasons why we should install valve positioner in a control system;
  1. The ability to control an instrumentation process precisely
  2. Increase of response ratio towards the changes in the process, possibility of a faster loading and faster output
  3. Option of split range (using one controller for two valves)
  4. Overcome the friction in rotary valves
  5. Option of using 4 to 20 mA signal
  6. Bringing the effects of the shaft’s friction and its resulting hysteresis to a minimum (this feature is very important for high temperature substances such as Graphite)
  7. Bringing high pressure drops to a minimum and compensating for the lack of internal force balance
  8. Option of using specific gears in rotary valves
This company offers valve positioner with Brazilian brand “Smar” and South Korean brand “YTC-Young Tech”.
CatalogsProducts
YTCValve Positioner
FY300 SMAR
FY400 SMAR