How to calibrate pressure transmitter using HART communicator?

Field Instrumentation Calibration
1

Requirements:

Power supply: To energize the transmitter,

250ohm resistor: To convert current into the voltage, which is suitable for the control systems.

Ammeter: ammeter is connected in series with the transmitter to measure the output current.

Pressure source: Can be the process pressure or hand pumps to produce pressure supply to the transmitter.

Pressure gauge: To measure the input pressure to the transmitter.

HART communicator: Used to view the pressure in the transmitter and to calibrate the pressure.

Procedure:

Calibrating Rosemount 1151 Pressure Transmitter.jpg663×376 30.3 KB

  • Do the connection as shown in the above figure.

  • Testing pressure is given to the HP line of the pressure transmitter and the LP line is set at ambient pressure, that is LP line is vented to atmosphere.

  • Apply a lower range pressure that is 0psi pressure in most cases. Check the HART communicator for the transmitter is showing the same value as the pressure gauge shows.

  • Check the ammeter reading also, an ammeter should show 4mA for 0psi pressure.

  • Do the same check procedure for high range value of the pressure gauge. The ammeter should read 20mA current and the HART communicator should read the high range value as in the gauge.

  • We need to calibrate the transmitter if transmitter shows incorrect value. That means if the transmitter shows.

  • If the current for the corresponding pressure is incorrect. Then correct the transmitter reading by adjusting the Span and Zero to make get the correct reading.

  • Rotate the span in a clockwise direction if the current value is showing lower the actual value should be. Or rotate anti-clockwise direction if the value is higher than the actual.

  • If the pressure showing in the HART communicator is different from the gauge. Then the transmitter should be calibrated using the HART communicator.

  • For calibration, we only need to check upper range value and lower range value.

  • If the HART is showing incorrect value for the upper range value or lower range value.

  • Go to settings in HART > select URV or LRV, based on which should be corrected change the value in the HART communicator > save the data into the transmitter.