[Xi’an Gigooda Electronic Technology Co. Ltd] To calibrate a pressure transmitter using a HART communicator,you have to follow the below steps.
1.Preparation before calibration:
a.Tool preparation: Prepare the HART communicator, pressure calibrator or pressure source, high-precision ammeter (if current monitoring is required), suitable connecting pipes and connectors and other tools.
b.Safety measures: Ensure that the calibration work is carried out in a safe environment, shut down the process where the pressure transmitter is located, cut off the power supply, and take appropriate protective measures to prevent accidents.
c.Equipment connection: Connect the pressure calibrator or pressure source to the pressure interface of the pressure transmitter through the connecting pipe; connect the HART communicator to the communication interface of the pressure transmitter to ensure that the connection is firm and the communication is normal.
2.Basic parameter setting and inspection:
a.Turn on the equipment: Turn on the pressure calibrator, HART communicator and related power supply equipment, and let the equipment preheat for a period of time to ensure its stable operation.
b.Enter the HART communication mode: Follow the operating instructions of the HART communicator to enter the communication interface with the pressure transmitter. The operation methods of different models of HART communicators may be slightly different, but there are usually corresponding menu options to choose from.
c.Check transmitter information: Check the basic information of the pressure transmitter in the HART communicator, such as model, range, accuracy, etc., and confirm that this information is consistent with the actual transmitter for subsequent calibration operations.
3.Zero calibration:
a.Empty pressure: Make sure that the pressure input of the pressure transmitter is zero, that is, it is in a state without pressure. If the pressure transmitter has an exhaust valve, open the exhaust valve to exhaust the internal pressure.
b.Perform zero adjustment: Find the option of zero calibration in the menu of the HART communicator, follow the prompts, and adjust the output of the pressure transmitter to zero. Some pressure transmitters may have an automatic zeroing function, which can also be operated through the zeroing button on the transmitter, but it is more accurate to calibrate using a HART communicator.
4.Range calibration:
a.Apply standard pressure: Use a pressure calibrator to generate a standard pressure signal, and apply different pressure values from small to large according to the range of the pressure transmitter, such as applying 25%, 50%, 75%, 100% of the range and other pressure points.
b.Record output value: After each pressure point is stable, read the output current value of the pressure transmitter through the HART communicator, compare it with the standard current output value, and record the error of each pressure point.
c.Adjust the range: If the output current value at a certain pressure point deviates from the standard value, correct the range of the pressure transmitter through the range adjustment function in the HART communicator. Generally speaking, the HART communicator will provide corresponding adjustment parameters, such as the upper limit of the range, the lower limit of the range, etc., and adjust according to the actual error situation.
5.Midpoint calibration (optional):
a.Select the middle point: Select some intermediate pressure points within the range, such as 30%, 60% of the range, etc., apply pressure again and record the output value of the pressure transmitter.
b.Check linearity: Check whether the output values of these middle points are consistent with the theoretical values to verify the linearity of the pressure transmitter. If the linearity is not good, further adjustment or checking whether there is a problem with the sensor of the pressure transmitter may be required.
6.Repeat calibration and verification:
a.Repeat operation: Repeat the above range calibration and midpoint calibration steps until the output values of the pressure transmitter at each pressure point meet the accuracy requirements.
b.Verify calibration results: After the calibration is completed, apply some random pressure values again to check whether the output of the pressure transmitter is accurate to verify the effect of the calibration.
7.Save calibration data:
a.Store data: In the HART communicator, save the calibrated parameters and data for subsequent query and reference. Some HART communicators can also transfer data to a computer or other storage device for more detailed analysis and management.
b.Mark the transmitter: Mark the calibration date, calibrator and other information on the pressure transmitter for future maintenance and management.
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