42/24-10 EN Rev. 9
Appendix 3: ZO23 Trace Oxygen Analyzer Module
A-3-9
Operating Specifications
Measurement
Principle
The ZrO
2
cell measures the difference in the oxygen concentration between the
reference side (with air) and the measuring side (with oxygen traces).
Linearity Deviation
Owing to the measurement principle, zirconium dioxide cells are base linear.
Repeatability
< 1 % of the measurement range or 100 ppb O
2
(whichever is greater)
Zero Drift
The zero point (reference point) is displayed if ambient air is present on the
sample gas side. The value for air of 20.6 Vol. % O
2
(for 25 °C and 50 % relative
humidity) may deviate through aging of the cell.
< 1 % of the measurement range per week or 250 ppb O
2
(whichever is greater)
Sensitivity Drift
Depends on possible interfering components (catalyst poisons) in the sample gas
and the aging of the cell.
For pure gas measurements in N
2
, CO
2
and Ar: < 1 % of the measurement range
per week or 250 ppb O
2
(whichever is greater)
Output Fluctuation
(2
σ
)
<
±
0.5 % of the measured value or 50 ppb O
2
(whichever is greater)
Flow Influence
≤
1% of the measured value or 100 ppb O
2
(whichever is greater) for a flow rate of
8
±
0.2 l/h.
The flow rate must be kept constant to
±
0.2 l/h in the permissible range. The
permissible range is 5 to 10 l/h. The flow rate is kept constant to 8
±
0.2 l/h with
integrated pump and flow control.
Associated Gas
Influence
Inert gases (Ar, CO
2
, N
2
) have no effect. Flammable gases (CO, H
2
, CH
4
) in
stoichiometric concentrations to the oxygen content: Conversion of O
2
< 20 % of
the stoichiometric conversion. If higher concentrations of flammable gases are
present, higher O
2
conversions must be expected. The concentration of flamma-
ble gases in the sample gas must not exceed 100 ppm.
Temperature
Influence
The effect of the ambient temperature in the permissible range of +5 to +45 °C is
< 2 % of the measured value or 50 ppb O
2
per 10 °C change in the ambient
temperature (whichever is greater).
Air Pressure
Influence
No effect through a change in air pressure; sample gas must flow out of the outlet
without back pressure.
Power Supply
Influence
24 V DC
±
5 %: no effect
Position Influence
No position effect for permanently installed instruments
T
90
Time
T
90
< 60 s for the alternation of 2 test gases in the measurement range 10 ppm
with a sample gas flow rate = 8 l/h and electronic T90 time = 3 s (applies to an
analyzer unit with 1 analyzer module)
