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Model 9110TH NOx Analyzer Calibration Procedures
Teledyne Analytical Instruments 219
9.6. CALIBRATION QUALITY ANALYSIS
After completing one 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, separately for NO and NO
X
. The values for these terms, both individually and
relative to each other, indicate the quality of the calibration.
To perform this quality evaluation, you will need to record the values of the following test functions (see
Section 4.1.1), all of which are automatically stored in the DAS channel CALDAT for data analysis,
documentation and archival.
NO OFFS
NO SLOPE
NOX OFFS
NOX SLOPE
Ensure that these parameters are within the limits listed in Table 9-5 and frequently compare them to
those values on the Final Test and Validation Data Sheet (P/N 04490) that came attached to your
manual, which should not be significantly different. If they are, refer to the troubleshooting Section 12.
Table 9-5: Calibration Data Quality Evaluation
Function Minimum Value Optimum Value Maximum Value
NOX SLOPE -0.700 1.000 1.300
NO SLOPE -0.700 1.000 1.300
NOX OFFS -20.0 mV 0.0 mV 150.0 mV
NO OFFS -20.0 mV 0.0 mV 150.0 mV
The default DAS configuration records all calibration values in channel CALDAT as well as all
calibration check (zero and span) values in its internal memory.
Up to 200 data points are stored for up 4 years of data (on weekly calibration checks) and a lifetime
history of monthly calibrations.
Review these data to see if the zero and span responses change over time.
These channels also store the STB figure (standard deviation of NO
X
concentration) to evaluate if
the analyzer response has properly leveled off during the calibration procedure.
Finally, the CALDAT channel also stores the converter efficiency for review and documentation.