Teledyne 9110T - Nitrogen Oxides Analyzer - Manual (Page 71)

Model 9110TH NOx Analyzer Getting Started
Teledyne Analytical Instruments 71
HNO
3
is a liquid at room temperature, so once the HNO
3
is released by the permeation tube it condenses
and collects along the 9110T’s wetted surfaces, While liquid HNO
3
does not directly effect the quality of
NO
x
measurements of the Model 9110T, it does give off small amounts of gaseous HNO
3
which is
converted into NO by the 9110T’s NO
x
 NO converter resulting in an artificially high NO
2
concentration by 8% to 12%. This is particularly bothersome when 9110T is attempting to measure a
zero point, such as during calibration, since the NO
2
concentration will only reach a true zero point once
the majority of the HNO
3
coating the wetted surfaces has reverted to NO
2
and this can take a very long
time.
The 9110T includes a special HNO
3
desorbed which eliminates any HNO
3
given off by the permeation
tube before it can be converted into NO by the analyzer’s converter.
PNEUMATIC LAYOUT FOR ZERO SCRUBBER AND IZS (OPT 50G)
Figure 3-27: Pneumatics with the Internal Span Gas Generator (OPT 50G)
Table 3-11: Internal Span Gas Generator Valve Operating States OPT 50G
MODE VALVE CONDITION
VALVE PORT
STATUS
SAMPLE Sample/Cal Open to SAMPLE inlet 3  2