pressure is an important physical quantity.In industries it should be maintained ,controlled,monitored at specific readings so that’s why pressure transmitters are so important  in industries . so calibration of pressure transmitter is what we are going to discuss now.

Equipments required for calibration of pressure transmitter

Pressure transmitter, multimeter, HART communicator

Basic procedure for calibration

  1. Isolate the Pressure Transmitter from the Process.
  2. Slowly open the vent plug and the vent valve to release the pressure.
  3. Connect the multimeter with the transmitter and ensure that output is 4ma when 0 pressures is applied.
  4. Connect the hand held test pump (pressure source) to the transmitter.
  5. Ensure there is no leak.
  6. Apply pressure range at 0%, 25%, 50%, 75%, 100% and check there is any error.
  7. If there is any error calibration should be done.

        If transmitter is analog transmitter

  1. Apply 0% pressure as per LRV with hand held test pump and check multimeter if it is not 4ma adjust the zero pot in the transmitter and correct transmitter output to 4ma
  2. Apply 100%pressure as per the URV and correct 20ma in multimeter by adjusting span pot in the transmitter
  3. Repeat these steps to rectify error.

In case of SMART Transmitter

  1. We have to use HART communicator,connect the communicator with the transmitter select the HART Communicator Menu for lower range value trim and upper range value trim.
  2. Basic Set up – Calibration – Zero Trim/Sensor Trim —Lower/Upper range value trims.
  3. HART communicator will automatically calibrate the transmitter.
  4. Restore the process connection
  5. Take the transmitter on line. Ensure there is no leak  

small example of five point calibration is given below

Low range value=0psi

upper range value=200psi

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