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Teledyne API Model 100AH SO
2
Analyzer Instruction Manual, 02417, Rev. D
8.8 Calibration Gases
The following are recommended for selecting calibration gas:
1. Concentration of span gas should be about 80% of the full scale range if direct cylinder span
gas is used without dilution. Also select reasonable range to operate for optimum instrument
performance such as linearity , noise, etc. For example, if the typical sample concentration is
about 300 PPM and the maximum peak concentration is about 800 PPM, then set the range to
1000 PPM and calibrate with 800 PPM of SO
2
gas. If the sample concentration is very low,
then set the range low accordingly or use AUTORANGE (refer Section 5.3.4) feature.
2. Cylinder source SO
2
gas should be balanced in nitrogen and diluted with nitrogen (ultrazero
grade). If diluted with dry zero air instead of nitrogen, it must be free of NO gas or other
contaminants.
3. Do not use blended gas of SO
2
and NO gas mixture in nitrogen. NO gas in nitrogen
interfere with the M100AH fluorescence SO
2
measurement. If the sample gas contains about
10% of CO
2
, then the interference from the NO gas will be reduced significantly. M100AH is
designed with special optical filter that rejects NO interference greater than 100 to 1 ratio.
Therefore with the special optical filter and mixture of CO
2
gas in the sample will result very
low NO gas interference.
8-9