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AO2000 CONTINUOUS GAS ANALYZERS | OI/AO2000-EN REV. B 261

Uras26: Notes for calibrating

Calibration

Calibration can be performed in range 1 and range 2 for each sample com-

ponent. It is always a common calibration and thus affects both measuring

ranges.

Calibration cells

The use of calibration cells allows the analyzer module to be calibrated

without using test gas containers.

A calibration cell can be installed in each of the analyzer module’s beam

paths. Each calibration cell is filled with a test gas matched to the sample

components and measurement ranges set up in the corresponding beam

path.

Test gases for zero calibration

A zero gas is required for zero calibration in any case.

In addition to nitrogen, ambient air can be used for zero calibration. Water

vapor must be absorbed using a cooler. If the ambient air contains sample

gas components, these must be removed with a suitable absorber (for CO:

HOPCALIT

, for CO

: Sodium hydroxide on substrate).

Test gases for end-point calibration without calibration cells

A test gas is required for each detector for span calibration without calibra-

tion cells. In the case of automatic and externally controlled calibration, a

test gas mixture is required for all detectors since all are calibrated simulta-

neously. The span gas concentration should be 70 to 80 % of the end value

of the largest measurement range.

Test gases for span calibration of suppressed ranges

For suppressed ranges, the span gas concentration must be within the sup-

pressed range. If possible it should be equal to the end value of the sup-

pressed measuring range (and thus the end value of the larger measurement

range).

Test gases for automatic calibration

In principle a test gas for each sample component is required for the inter-

nally or externally controlled automatic calibration.

A test gas mixture containing each sample component in the appropriate

concentration may be used only when all sample components have no mutu-

al cross-sensitivity and/or carrier gas influences.

ABB AO2020 User Manual

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