Thermo 42i - Preparing NO, Nox, and NO2 Calibration Curves

Calibration
Calibration
Thermo Electron Corporation Model 42i Low Source Instruction Manual 4-9
The NO
x
recorder response will equal:
Where:
URL = Nominal upper range limit of the NO
x
channel, ppm
Record the NO
x
concentration and the analyzer's NO
x
response.
Preparing NO, NOx, and
NO2 Calibration Curves
Use the following procedure to prepare the NO, NO
x
, and NO
2
calibration
curves.
1. Generate several additional NO and NO
x
concentrations by decreasing
F
NO
or increasing F
D
.
2. For each concentration generated, calculate the exact NO and NO
x
concentrations using the above equations for [NO]
OUT
and [NO
x
]
OUT
.
3. Record the NO and NO
x
responses.
4. Plot the analyzer responses versus the respective calculated NO and
NO
x
concentrations and draw or calculate the respective calibration
curves. For subsequent calibrations where linearity can be assumed,
these curves may be checked with a three-point calibration consisting of
a zero point, NO and NO
x
concentrations of approximately 80% of the
URL, and an intermediate concentration
5. Adjust the GPT system to generate a NO concentration near 90% of
the URL of the instrument range selected.
6. Sample this NO concentration until the NO and NO
x
responses have
stabilized, then measure and record the NO concentration as
[NO]
ORIG
.
7. Adjust the O
3
generator in the GPT system to generate sufficient O
3
to
produce a decrease in the NO concentration equivalent to about 80%
Z
+100 x
URL
]
NO
[
=scale)(%ResponseRecorder
NO
OUT
x
x