ABB ACF-NT, Operator'S Manual

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42/23-572 EN Rev. 5 Operator’s Manual ACF-NT, ACF-NT V0309 31
Calibration
FTIR Spectrometer
Zero Spectrum The zero spectrum is recorded automatically twice a day. It is used for zero and
sensitivity corrections. The zero spectrum is also named reference spectrum.
Zero calibration is described in detail in the “FTIR Spectrometer Zero Calibration”
section (see page 33).
FTIR Spectrometer
Span Check The span check maintenance interval is 6 months. If a deviation greater than 4 %
results during span check, the span must be adjusted using test gases. Span
check is described in detail in the “FTIR Spectrometer Span Check” section (see
page 35).
Zero spectrum:
Purified Air (“Zero Gas”)
Span check: 1 SO
2
+ CO + NO + rest N
2
2 HCl in N
2
3 NH
3
in N
2
Supplied at test gas
port
Alternative for 2 HCl + H
2
O + air from evaporator
Alternative for 3 NH
3
+ H
2
O + air from evaporator
4 H
2
O in air from evaporator
Test Gases for
FTIR Spectrometer
Span Check
5 HF + H
2
O + air from evaporator
Supplied directly to
sample conditioning
block or sample gas
line

Before each test gas change, purge the test gas paths with the zero gas for at
least 10 minutes. In case of NH
3
span check use this test gas as the last to
avoid reactions with other gases.

Setting and checking the water cross-sensitivity correction against the other
sample components must be performed using the cleaned instrument air
available in the analyzer system as carrier gas for the water vapor generator.

For the measurement of HF, checking the water vapor cross-sensitivity must be
ensured:

during initial start-up by the manufacturer’s or the supplier’s qualified
personnel,

in the annual functional tests by an accredited measurement institute as per
EN 17025.

The measured values are indicated in wet mg/Nm
3
. Pressure or temperature
correction is not required since sample gas and test gas are measured under
the same conditions.
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