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Use the following procedure to set the NO and NOx backgrounds to zero.
Both the NO and NO
Note The NO channel should be calibrated first and then calibrate the
NO
channel.
▲
x
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
Titrator" earlier in this chapter. The total GPT airflow must exceed the
total demand of the analyzer. The 42iQ requires approximately 700
cc/min of sample flow, and a total GPT airflow of at least 1.5 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 Home Screen, choose
Calibration>Calibrate Backgrounds>Calibrate NO Background.
The Target NO Concentration button will read 0.00. The
Calculated NO Background button will display the background
needed to make the current NO concentration go to 0.00.
c. Press Calibrate to set the NO reading to zero and to save the new
background.
d. Press the Back button to return to the Calibration Backgrounds
screen and repeat this procedure to set the Calibrate NOx
Background to zero.
e. Record the stable zero air responses as Z
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:
background screens operate the same way.
x
"Dynamic Parameter
Titrator" earlier in this chapter.
generator air flows to obtain the
3
"Dynamic Parameter Specifications for Gas
x
F
NO
NO
[NO
=
]
OUT
+
F
F
NO
O
Calibration
, and NO
2
, Z
, and Z
.
NO
NOX
NO2
STD
+
F
D
42iQ Instruction Manual
Calibration
x
4-11
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