YOKOGAWA EXAxt ZR402G, User Manual

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<1. Overview>
1-3
IM 11M12A01-04E 11th Edition : Jul. 19, 2017-00
1.1.3 System 3
This example, System 3, represents typical applications in large boilers and heating furnaces,
where 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 ZR20H 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.
~
100 to 240 V AC
Automatic calibration unit
Reference gas
Calibration gas (Zero)
Contact input
Analog output, contact output
Digital output (HART)
Air Set
Instrument air
Calibration gas unit case
Calibration
gas pressure
regulator Zero gas cylinder
ZR202G Integrated type Zirconia Oxygen/Humidity Analyzer
with automatic calibration unit (ZR202G-
□
-
□
-
□
-A-
□
-
□
-
□
-
□
-A)
F1.3E.ai
Span gas
ZR20H
*3
Note:
The installation temperature limits range for integrated type analyzer is -20 to 55°C.
*2
*1
*
1 Shield cable:
Use shielded signal cables, and connect the shields 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 approx. 1 vol% O
2
gas (N
2
-based).
Figure1.3 Example of System 3