WPI APOLLO 4000, Instruction Manual

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APOLLO 4000
OXYGEN DETECTION
World Precision instruments d-3
Gas Phase Measurements
Probe calibration for gas phase measurements can be accomplished using the
calibration bottle,as described above for zeroing the instrument with nitrogen,
using a tank of known oxygen composition, for example 00 % o
2
.
Alternatively, air can be used as the calibration standard but since water vapor
does affect the probe reading it is best to use dry air unless the ambient humidity is
accurately known. dry air can be obtained by passing room air through a column
containing a solid drying agent such as silica gel or calcium chloride and then into
the calibration bottle for calibration. Ambient humidity may cause a calibration error
of as much as % o
2
. the user may judge if this is acceptable.
Fig. D2
—
Oxygen calibration
trace in nA.