YOKOGAWA ZR22S, User Manual

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<1. Overview>
1-2
IM 11M13A01-02E
1.1.2 System 2
This example, System 2, 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 2 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.
Instrument air
Pressure
regulating
valve
Air Set
Needle
valve
Flowmeter
Reference gas
Calibration gas
Check valve
~
Zero gas cylinder
ZR40H
Automatic Calibration Unit
Zirconia Oxygen Analyzer, Detector
ZR402G Converter
Calibration gas
unit case
F01-2E.ai
ZR22S Separate type Explosion-proof
EXA ZR402G
100 to 240 V AC
Contact input
Analog output, contact output
Digital output (HART)
*2
Non-hazardous Area Hazardous Area
Signal
(6-core shield cable)
Heater (2-core cable)
*1
*1: Shield cable;Use shielded signal cables, and connect the shield to the FG terminal of the converter.
*2: 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).
Figure 1.2 System configuration 2