Yokogawa In-Situ Gas Analyzer TDLS200 - Manual (Page 81)

6-24 6-25
IM 11Y01B01-01E-A 6th Edition :Feb 13, 2013-00
<6. BASIC OPERATION>
On-Line Process Conditions – Analyzer Purged with Nitrogen:
When purging with Instrument Air (as opposed to ambient air), the H
2
O levels are much smaller (due to it
having been dried and having a dew point typically in the order of -40˚C) and therefore the H
2
O
concentration is not large enough to produce an absorption peak that can be seen.
Process OPL: Zero NH
3
+ Zero H
2
O
Analyzer Purge: Air (typical ~2-4% H
2
O)
In this Absorption Spectra view, the analyzer air purge H
2
O
absorption peak can be seen at approximate peak center position
(PCP) 167.
There is no NH
3
absorption in the spectra.
Process OPL: ~20 ppm NH
3
+ Zero H
2
O
Analyzer Purge: Air (typical ~2-4% H
2
O)
In this Absorption Spectra view, the H
2
O absorption (analyzer air
purge) peak can be seen at approximate peak center position (PCP)
167.
There is approximate 20 ppm NH
3
absorption (approx 120PCP)
in this spectra based on 72.6 cm OPL, ambient temperature and
ambient pressure.
Process: Zero NH
3
+ ~2% H
2
O
Analyzer Purge: Air (typical ~2-4% H
2
O)
In this Absorption Spectra view, the process gas H
2
O (~2% 0.7 m
@ STP) and analyzer air purge H
2
O absorption peak can be seen at
approximate peak center position (PCP) 167.
There is no NH
3
absorption in the spectra.