Use this procedure if you wish to perform a calibration with applied pressure. Apply a pressure to your transmitter that is equal to or near the LRV. Key in that pressure as the pressure for the lower trim point when requested. Similarly, apply a pressure equal to or near the URV and key in that pressure for the upper trim point.
Transmitters are factory characterized and calibrated. There is usually no need for the user to do a pressure calibration. The Zero Trim function (described below) can be used to correct for position effects and Reranging (described above) can be used to change the range.
Your transmitter uses its factory entered and stored characterization and calibration data to convert any input pressure within range limits to a digital value of pressure which can be transmitted, displayed, and converted into a mA current signal.
However, if a pressure calibration is desired, use the Pressure Calibration function to trim the internal digital values of the interpreted pressures based on precise user entered values of the applied lower and upper range pressures.
Also, at times it is desirable to perform a single point calibration (or zeroing) with a nonzero pressure input while not affecting the span.
For example, to zero an absolute pressure transmitter at a measured atmospheric pressure, use a trim point within the Pressure Calibration function to achieve a single point calibration that does not change the span.