Thermo Scientific 42i Instruction Manual page 143

Calibrate the NO Channel to the
NO Calibration Gas
Thermo Fisher Scientific
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 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 Main Menu, choose
Calibration > Cal NO Background.
c. Press to set the NO reading to zero.
d. Press to return to the Calibration menu and repeat this
procedure to set the 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
Use the following procedure to calibrate the NO channel to the NO
calibration gas.
1. Allow the analyzer to sample the NO calibration gas until the NO,
NO , and NO readings have stabilized.
2 x
2. When the responses stabilize, from the Main Menu, choose Calibration
> Cal NO Coefficient.
generator air flows to obtain the
3
background to zero.
x
x
F NO
NO
[NO =
]
OUT
+ +
F F
NO O
Calibration
Calibration
, and NO
x
, Z , and Z
NO NOX NO2
STD
F
D
Model 42i Instruction Manual
2
4-11