YOKOGAWA EXAxt ZR22G, User Manual, Page: 18 / 211

<1. Overview>
1-3
IM 11M12A01-02E 16th Edition : Mar. 19, 2020-00
F1-2E.ai
ZR402G Converter
Check valve
or Stop Valve
ZA8F Flow Setting Unit
EXA ZR402G
ZR22G Separate type
Zirconia Oxygen/Humidity Analyzer, Detector
100 to
240 V AC
Air Set
Instrument air
Calibration gas
Reference
gas
Flowmeter
Needle
valve
Calibration gas
unit case
Zero gas
cylinder
Span gas
(Same as Zero gas calibration unit)
Contact input
Analog output, contact output
(Digital output HART)
Signal
(6-core shield cable)
Heater(2-core)
~
Pressure
reducing
valve
Figure1.2
1.1.3 System 3
This example, System 3, represents typical applications in large boilers and heating furnaces,
where there is a need to monitor and control oxygen concentration. The reference gas and
calibration-time span gas are (clean, dry) instrument air. Zero gas is supplied from a gas cylinder.
System 3 uses the ZR40H automatic calibration unit, with auto-switching of the calibration gas.
A “combustible gas detected” contact input turns off power to the heater. There’s also contact
output from the converter that can be used to operate a purge gas valve to supply air to the
sensor.
F1-3E.ai
ZR22G Separate type
Zirconia Oxygen/Humidity Analyzer, Detector
ZR402G Converter
Signal
(6-core shield cable)
Heater (2-core)
Reference gas
Calibration gas
Flowmeter Needle
valve
Zero gas cylinder
100 to 240 V AC
*3
Check valve
Contact input
Analog output, contact output
Digital output (HART)
Air Set
lnstrument air
Pressure
reducing
valve
EXA ZR402G
*1
*2
~
Calibration gas
unit case
ZR40H
Automatic Calibration Unit
*1 Shield cable ; Use shielded signal cables, and connect the shield to the FG terminal of the converter.
*2 Select the desired probe from the Probe Configuration table on page 1-4.
*3 When a zirconia oxygen analyzer is used, 100% N
2
gas cannot be used as the zero gas. Use approximately 1% of O
2
gas (N
2
-
based).
Figure1.3