AO2000 CONTINUOUS GAS ANALYZERS | OI/AO2000-EN REV. B 233
Notes for calibrating analyzer modules
Caldos25: Notes for calibrating
Sample components
The analyzer module has at least one sample component with 1 range.
Associated gas effect
The analyzer module measurement technique is based on the differing
thermal conductivity of various gases.
Since this technique is non-selective, the concentration of a sample compo-
nent can be accurately measured only in a binary or quasi-binary gas mix-
ture.
If other associated gas components are present in the sample gas their
effect on initial factory calibration must be considered.
Test gases
Zero calibration: Test gas or sample-component-free process gas or substi-
tute gas
Span calibration: Test gas or process gas having a known sample gas con-
centration or substitute gas
Test gas for corrected sample components
During calibration possible electronic cross-sensitivity and/or carrier gas
corrections by other measurement components are switched off. Therefore,
corrected measurement components should be calibrated only using a test
gas consisting of the measurement component and an inert gas like Nitro-
gen.
Calibration with substitute gas
If test gases are not available for calibration, the analyzer module can be
factory-set for calibration with a substitute gas (see also section "Calibra-
tion methods" (see page 223)). This setting is documented in the analyzer
data sheet.
Substitute gas calibration of the analyzer module is described using the
example of "CO
2
measurement in flue gas" (see page 237).
Sequence of calibration
Zero-point calibration must always precede end-point calibration.
Wait until the warm-up phase has ended
The analyzer module should only be calibrated after the warm-up phase (see
page 135).
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