2 calibration gas, Calibration procedures -6, With a balance of nitrogen gas (n – Yokogawa Integral Oxygen Analyzer ZR202 User Manual
Page 120
IM 11M12A01-05E
9-3
9. Calibration
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Humidity, vol % H2O
Mixing ratio, kg/kg
Humidity
, vol % H
2
O
Oxygen concentration, vol % O
2
FBE.EPS
Mixing ratio kg/kg
Oxygen concentration vs, Humidity, Mixing ratio
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 -208C 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.