Fluke RPM4 manual Adjustment of ON-BOARD Barometer

5. MAINTENANCE, ADJUSTMENTS AND CALIBRATIONS

Run the recommended calibration point sequence for the Q-RPT (see Section 5.2.4). Record the pressure applied by the standard and the RPM4 reading at each calibration point. Dwell at least 60 seconds at each point after setting the reference pressure to allow full stabilization The data recorded is the “as received” data for this calibration.

Enter the calibration pressures and RPM4 readings into a spreadsheet. Calculate the “non-corrected” RPM4 readings by backing out the PA, PM and Poffset (Poffset in the case of Axxx (absolute) Q-RPTs in absolute mode only, do not back out Poffset for for gauge mode calibrations) recorded in Steps and above, following:

non-corrected reading = ((corrected reading - PA)/PM ) + Poffset

Perform a linear regression to find the offset and slope that best fit the non-corrected RPM4 readings to the calibration standard pressures. The offset is the new value of PA, the slope is the new value of PM.

Press [SPECIAL], <8Cal>, <1Hi RPT> or <2Lo RPT>, <2edit> and write the new calibration date and the new values of PA and PM for the Q-RPT calibrated (see Section 5.2.7). If this is an Axxx Q-RPT and the calibration was performed in gauge mode, turn absolute and negative gauge modes OFF to avoid their being used after the calibration.

Calculate as left data for the calibration if desired following:

as left reading = (non-corrected reading • new PM) + new PA

Perform additional verification pressure runs as desired.

5.3ADJUSTMENT OF ON-BOARD BAROMETER

PURPOSE

To adjust the output of the on-board barometer (see Section 1.2.2.2).

RPM4’s that have only G100K or G200K Q-RPTs (no Axxx or G15K or BGxxx) are NOT equipped with an on-board barometer.

PRINCIPLE

The on-board barometer output can be adjusted using PA and PM values in the same manner as Q-RPTs (see Section 5.2.1.1).

The on-board barometer is a low accuracy sensor used only for measuring changes in atmospheric pressure over short periods of time (see Section 3.2.2) and the line pressure for G15KK and BG15K line pressure compensation. RPM4 measurement uncertainty does not depend on the measurement uncertainty of the on-board barometer.

OPERATION

To edit the values of PA and PM for the barometer, press [SPECIAL], <8cal>, <3barometer>. Pressing [ENT] steps through displays of the calibration date (YYYYMMDD) and PA and PM. In edit mode, the values can be edited. Pressing [ENT] after the last screen activates the edited values.

To view the current output of the on-board barometer, press [SPECIAL], <7Internal>, <3baro>.

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