ABB AO2040 - Page 250

250 AO2000 CONTINUOUS GAS ANALYZERS | OI/AO2000-EN REV. B
Analyzer with internal cross-sensitivity correction
During calculation possible electronic cross-sensitivity and/or carrier gas
corrections by other measurement components are disabled for the calcula-
tion. The following information should therefore be noted in particular:
All the sample components must always be calibrated in the following se-
quence for the zero-point calibration:
• First that sample component which is not corrected,
• Afterwards that sample component which is affected by the smallest
number of corrections,
• Up to that sample component which is affected by the largest number
of corrections.
Example
Sample components NO, SO
2
, NO
2
Cross-sensitivity correction NO by SO
2
and NO
2
,
SO
2
by NO
2
,
NO
2
not corrected.
Sequence for zero-point calibration 1. NO
2
, 2. SO
2
, 3. NO.
All the sample components must also always be calibrated in the end-point
calibration. Here, a corrected sample component may only be calibrated
using a test gas contain no components which cause cross-sensitivity, i.e.
which only consists of the sample component and an inert gas, e.g. N
2
.
Wait until the warm-up phase has ended
The analyzer module should only be calibrated after the warm-up phase (see
page 135).
Limas21 HW: Special notes for calibrating NO
2
and NH
3
Calibration with calibration cells
We recommend using the calibrating cells installed as an option in the gas
analyzer for calibrating NO
2
and NH
3
.
During the calibration with calibration cells zero gas must be connected.
Clean and dust-free ambient air can also be used as a test gas.
The zero gas should be applied at the sample gas path inlet in order to ap-
proximate the conditions in measurement operation as closely as possible
during calibration.
The zero gas should be humidified to prevent the sample gas feed from
drying out during calibration and intake times consequently being too long
after switching back to measurement mode.
Calibration with test gases
We recommend calibrating the gas analyzer every 6 to 12 months with test
gas.
Zero gas and test gas should be connected directly at the gas analyzer to
avoid intake times being too long.