Control valve stroke checking

What is a control valve?

Control valve is a power operated device which modifies the fluid flow rate in a process control system; consists of a valve connected to an actuator mechanism that is capable of changing the position of a flow controlling element in the valve in response to a signal from the controlling system

Control valve stroke checking

This method for demonstrating that the actuator has adequate force to open and close the valve. The procedure shall demonstrate that no mechanical damage or permanent deformation of valve components will occur and that accessories function properly

Equipment and Materials

  •  Air Instrument
  • Loop Calibrator ( 4 – 20 mA)
  •  Connector
  •  Tubing and ferrule sets

Procedure

  1. Connect control valve and its accessories as per connection dig(consider control valve is a air to close valve)
  2. Apply Air Instrument for Supply pressure to Regulator
  3. Adjust Regulator until pressure as per datasheet for Supply Pressure to POSITIONER
  4. Set Loop Calibrator to provide current Input Signal (4-20mA) to POSITIONER
  5. Apply 4 mA to positioner  using loop Calibrator
  6. Check the stem movement it must be at minimum position if there is any error adjust the zero calibrating screw in positioner
  7. Apply 20 mA
  8. Check the  stem position it must be at 100% position ,if there is any error adjust the span screw in the positioner
  9. Apply 0%,25%,50%,75%,100% of the signal &  observe the corresponding stroke of the valve & stem position

Also read about Control valves link below

https://automationforum.co/?s=Control+valve

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