YOKOGAWA EXAxt ZR22G, User Manual, Page: 70 / 211

<4. Piping>
4-5
IM 11M12A01-02E 16th Edition : Mar. 19, 2020-00
4.2 Piping for System 2
Piping in System 2 is illustrated in Figure 4.7.
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ZA8F Flow Setting Unit
EXA ZR402G
ZR22G Separate type
Zirconia Oxygen/Humidity Analyzer, Detector
ZR402G Converter
Reference
gas
Calibration
gas
Needle
valve
Flowmeter
Instrument air
Air Set
Pressure
reducing
valve
Zero gas cylinder
Calibration gas
unit case
F4-7E.ai
Stop valve
or Check valve
Span gas
(Same as Zero gas Calibration)
Signal
(6-core shield cable)
Contact input
Analog output, Contact input
Digital output (HART)
Heater (2-core)
100 to
240 V AC
Figure 4.7 Piping for System 2
System 2 illustrated in Figure 4.7 requires piping as follows:
• Connect a stop valve or check valve the nipple at the calibration gas inlet of the detector.
• It is recommended to use ZH21B dust protector to protect the probe output from dust
agitation (i.e., to prevent combustible materials from entering the probe cell) where humidity
measurements are made under dusty or combustible environment.
• If a high temperature detector is used and the sample gas pressure is negative, connect
an ejector assembly to the sample gas exhaust hole of the high temperature probe adapter
(see Section 4.1.4, Figure 4.3).
• If a high temperature detector is used and the pressure of the sample gas is 0.49 kPa or
higher, it is recommended that a needle valve (throttle) be used in the sample gas exhaust
of the high temperature probe adapter (see Section 4.1.4, Figure 4.4).
CAUTION
This is for lowering the sample gas temperature below 700 ° C. If the gas temperature is high and
the pressure is also significantly high, the sampled gas temperature may not reduced below
700 ° C when reaching the detector.
On the other hand, if the sample gas temperature is lowered too much, condensation may be
produced in the high temperature probe adapter. During wintertime, it is recommended that the
high temperature probe adapter be protected with an insulating material to prevent condensation
(see Section 4.1.4, Figure 4.5).
For the usage of the high temperature probe adapter, refer to Section 3.2.1.
• If the dust sticking to the interior of the high temperature probe adapter is to be eliminated by
blow back while using the high temperature detector, the air feed for blow back should also
be taken into consideration.
CAUTION
The probe is easily clogged if too much dust is contained in the sample gas such as in a utility
boiler or cement kiln. To get rid of the dust with compressed air, the piping from the air source is
connected only during cleaning. Blow back piping can be installed for dust cleaning as illustrated
in Section 4.3.1.