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
- Isolate the Pressure Transmitter from the Process.
- Slowly open the vent plug and the vent valve to release the pressure.
- Connect the multimeter with the transmitter and ensure that output is 4ma when 0 pressures is applied.
- Connect the hand held test pump (pressure source) to the transmitter.
- Ensure there is no leak.
- Apply pressure range at 0%, 25%, 50%, 75%, 100% and check there is any error.
- If there is any error calibration should be done.
If transmitter is analog transmitter
- 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
- Apply 100%pressure as per the URV and correct 20ma in multimeter by adjusting span pot in the transmitter
- Repeat these steps to rectify error.
In case of SMART Transmitter
- 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.
- Basic Set up – Calibration – Zero Trim/Sensor Trim —Lower/Upper range value trims.
- HART communicator will automatically calibrate the transmitter.
- Restore the process connection
- 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