YOKOGAWA EXAxt ZR22G, User Manual, Page: 17 / 211

<1. Overview>
1-2
IM 11M12A01-02E 16th Edition : Mar. 19, 2020-00
EXA ZR402G
ZR22G Separate type
Zirconia Oxygen/Humidity Analyzer, Detector
ZR402G Converter
Stop valve
Calibration gas
ZO21S Standard gas unit
~
100 to
240 V AC
F1-1E.ai
Contact input
Analog output, contact output
(Digital output HART)
Signal
(6-core shield cable)
Heater(2-core)
~
Figure1.1
NOTE
• As this system uses ambient air for the reference gas, measuring accuracy will be affected
by the installation location.
• A needle (stop) valve should be connected to the calibration gas inlet of the detector.
The valve should be fully closed unless calibration is in progress.
1.1.2 System 2
This system is for monitoring and controlling oxygen concentration in the combustion gases of a
large-size boiler or heating furnace. Clean (dry) air (21 vol%O
2
) is used as the reference gas and
the span gas for calibration.
In case of humidity analyzer, this system is for accurate monitoring and controlling humidity when
the installation environment is polluted with gases other than the air. Instrument air (clean and dry
air of oxygen concentration 21%) is used for the reference gas and the span gas for calibration.
Zero gas is fed in from a cylinder during calibration. The gas flow is controlled by the ZA8F flow
setting unit (for manual valve operation).