Yokogawa Single Channel Oxygen Analyzer System ZR22/ZR402 - Manual (Page 139)

IM 11M12A01-03E 9-3
9. Calibration
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Humidity
, vol % H
2
O
Oxygen concentration, vol % O 2
FBE.EPS
Oxygen concentration vs. Humidity, Mixing ratio
Humidity, vol % H2O
Mixing ratio, kg/kg
Mixing ratio kg/kg
9.1.2 Calibration Gas
A gas with a known oxygen concentration is used for calibration. Normal calibration is
performed using two different gases: a zero gas of low oxygen concentration and a span
gas of high oxygen concentration. In some cases, only one of the gases needs to be used
for calibration. However, even if only one of the gases is normally used, calibration
using both gases should be done at least once.
The zero gas normally used has an oxygen concentration of 0.95 to 1.0 vol%O
2
with a
balance of nitrogen gas (N 2 ). The span gas widely used is clean air (at a dew-point
temperature below -20
Њ C and free of oily mist or dust, as in instrument air).
For best accuracy, as the span gas use oxygen whose concentration is near the top of the
measurement range, in a nitrogen mixture