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For detailed information about the menu parameters and the icons used in
these procedures, see the "Operation" chapter.
1. Determine the GPT flow conditions required to meet the dynamic
parameter specifications as indicated in
Specifications for Gas
2. Adjust the GPT diluent air and O
flows determined in "Dynamic Parameter Specifications for Gas Phase
Titrator" earlier in this chapter. The total GPT airflow must exceed the
total demand of the analyzer. The Model 42i Trace Level requires
approximately 1 liter/min of sample flow, and a total GPT airflow of at
least 2.5 liters/min is recommended.
a. Allow the analyzer to sample zero air until the NO, NO
responses stabilize.
b. After the responses have stabilized, from the Main Menu, choose
Calibration > Cal Prereactor Zero.
c. Press
to set the zero concentration reading to zero.
d. Press
to return to the Calibration menu and repeat this
procedure to set the NO and NO
e. Record the stable zero air responses as Z
(recorder response, percent scale).
3. Adjust the NO flow from the standard NO cylinder to generate a NO
concentration of about 80% of the upper range limit (URL) of the NO
range. The exact NO concentration is calculated from:
Where:
[NO]
= Diluted NO concentration at the output manifold, ppm
OUT
NO
= No feed concentration
STD
F
= No flow
NO
F
= Ozone flow
O
F
= Dilution flow
D
"Dynamic Parameter
Titrator" earlier in this chapter.
generator air flows to obtain the
3
background to zero.
x
x
F
NO
NO
[NO
=
]
OUT
+
+
F
F
NO
O
Model 42i Trace Level Instruction Manual
Calibration
Calibration
, and NO
x
, Z
, and Z
NO
NOX
NO2
STD
F
D
2
4-11
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Troubleshooting
