ABB EL3000 Series Manual page 29

Test gases
Purge gas
Gas connections
Installation and sample conditioning
EL3000 CONTINUOUS GAS ANALYZERS
Reference point (= electrical zero)
Clean ambient air; its oxygen concentration can be calculated from the value
for dry air and the factor for the consideration of the water vapor content.
Example:
Water vapor content at 25 °C and 50 % relative humidity = 1.56 Vol.-% of H
 factor 0.98
Oxygen concentration = 20.93 Vol.-% of O
End-point
Test gas with oxygen concentration in the smallest measurement range (e.g.
2 ppm O in N )
2 2
NOTES
The pressure conditions at reference point and end-point must be identical.
Notes for checking the reference point and end-point must be considered.
If a housing purge is selected (only in IP54 version), purging may only be
carried out with air (not with nitrogen) as the ambient air serves as a refer-
ence gas.
see sections
"Gas connections ZO23 (Model EL3020)" (see page 75) and
"Gas connections ZO23 (Model EL3040)" (see page 76)
CAUTION
The ingress of liquids into the analyzer module can cause serious damage
including destruction of the sample cell.
NOTE
The following information on installation and the sample conditioning must
be considered for the measurement and the execution of controlled calibra-
tions (manual, automatic and externally controlled calibration). Manually
operated cocks and valves must be replaced by controlled valves suitable for
the oxygen trace measurement, as required.
| CI/EL3000-EN REV. B
 0.98 = 20.6 Vol.-% of O
2
29
O
2
2