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Teledyne API - Model T200H/T200M Operation Manual
8.1.2. NO
AND NO
X
xNO
Sample
Gas
07270D DCN7141
DETERMINATION
2
The only gas that is truly measured in the T200H/M is NO. Any NO
is not detected in the above process since NO
luminescence.
In order to measure the concentration of NO or NO
NO and NO
in the sample gas), the T200H/M periodically switches the sample gas
2
stream through a converter cartridge filled with molybdenum ("moly") chips heated to a
temperature of 315° C. The heated molybdenum reacts with NO
produces a variety of molybdenum oxides and NO according to Equation 9-4.
+
→
yMo
xNO
2
Once the NO
in the sample gas has been converted to NO, it is routed to the reaction cell
2
where it undergoes the chemiluminescence reaction described in Equations 9-1 and 9-2.
Molybdenum Converter
NO
+ Mo
NO + Mo
2
(All NO
2
Exhaust
Figure 8-2:
By converting the NO
in the sample gas into NO, the analyzer can measure the total NO
2
(NO+NO
) content of the sample gas. By switching the NO
2
sample gas stream every 6 - 10 seconds, the T200H/M analyzer is able to quasi-
continuously measure both the NO and the total NO
The NO
concentration, finally, is not measured but calculated by simply subtracting the
2
known NO content of the sample gas from the known NO
2
+
M
O
oy
z
NO/NO
Valve
NO + NOx
o
O
at 315
C
y
2
converted to NO)
REACTION
CELL
NO
Conversion Principle
2
Principles of Operation
contained in the gas
2
does not react with O
to undergo chemi-
3
(which is defined here as the sum of
X
in the sample gas and
2
°
(
at
315
C
)
X
O
Generator
3
O
Scrubber
3
converter in and out of the
2
content.
X
content.
X
(Equation 9-4)
X
267
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