Thermo Scientific 42iQLS, Instruction Manual

Page: 179 / 318

Calibration
Calibration
Thermo Scientific 42iQLS Instruction Manual 4-13
is pressed. Pressing the Calibrate button will save the new NO
x
span
coefficient and calibrate the instrument.
3. Enter the NO
x
calibration gas concentration using the pushbuttons,
and then press Calibrate to calibrate the instrument to the NO
x
calibration gas.
The exact NO
x
concentration is calculated from:
F
+
F
+
F
)
]
NO
[ +
]
[NO ( x
F
=
]
NO
[
D O NO
IMP
2
STD
NO
OUT
x
Where:
[NO
x
]
OUT
= diluted NO
x
concentration at the output manifold, ppm
[NO
2
]
IMP
= concentration of NO
2
impurity in the standard NO cylinder, ppm
4. Record the NO
x
concentration and the analyzer's NO
x
response.
Use the following procedures 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
.
Preparing NO, NO
x
, and
NO
2
Calibration Curves