083730300A DCN8101 Calibration 99
4.4 CO CALIBRATION QUALITY
After completing any of the calibration procedures described above, it is important to
evaluate the analyzer’s calibration SLOPE and OFFSET parameters. These values
describe the linear response curve of the analyzer. The values for these terms, both
individually and relative to each other, indicate the quality of the calibration.
To perform this quality evaluation, check that these parameters are within the limits listed
in Table 4-4 below and frequently compare them to those values on the Final Test and
Validation Data Sheet that was shipped with your instrument, which should not be
significantly different. If they are, refer to the Troubleshooting content in Section 5.
Table 4-4. Calibration Data Quality Evaluation
4.5 CALIBRATION OF THE T300/T300M’S ELECTRONIC
SUBSYSTEMS
These calibrations include Dark Cal, Pressure Cal and Flow Cal, all located under the
Utilities>Diagnostics menu.
4.5.1 DARK CALIBRATION TEST
The dark calibration test interrupts the signal path between the IR photo-detector and the
remainder of the sync/demod board circuitry. This allows the instrument to compensate
for any voltage levels inherent in the sync/demod circuitry that might affect the
calculation of CO concentration.
Performing this calibration returns dark offset voltages for MEAS and for REF that are
automatically added to the CPU’s calculation routine. The two offset voltages from the
last calibration procedure may be viewed in the Dashboard as Meas Detector and Ref
Detector.
Activate this procedure in the Utilities>Diagnostics>Dark Calibration menu.
4.5.2 PRESSURE CALIBRATION
A sensor at the exit of the sample chamber continuously measures the pressure of the
sample gas. The data for Sample Pressure are used to compensate the final CO
concentration calculation for changes in atmospheric pressure and are stored in the CPU’s
memory.
IMPORTANT
IMPACT ON READINGS OR DATA
This calibration must be performed when the pressure of
the sample gas is equal to ambient atmospheric pressure.
Before performing the following pressure calibration
procedure, disconnect the sample gas pump and sample
gas-line vent from the rear panel sample gas inlet.
Activate this procedure in the Utilities>Diagnostics>Pressure Cal menu.
0.700 1.000 1.300
-0.500 0.000 0.500
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