Calibration
Calibration
4-14
Model 42
i
Trace Level Instruction Manual
Thermo Fisher Scientific
a zero point, NO and NO
x
concentrations of approximately 80% of the
URL, and an intermediate concentration.
5.
Sample this NO concentration until the NO and NO
x
responses have
stabilized, then measure and record the NO concentration as [NO]
ORIG
.
6.
Adjust the GPT system to generate a NO concentration near 90% of
the URL of the instrument range selected.
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%
of the URL of the NO
2
range. The decrease must not exceed 90% of
the NO concentration determined in Steps 5 and 6 above.
8.
When the analyzer responses stabilize, record the resultant NO
concentrations as [NO]
REM
.
9.
From the Main Menu choose Calibration >
Cal NO2 Coefficient
.
The NO
2
line of the Calibrate NO
2
screen displays the current NO
2
concentration. The SPAN CONC line of the display is where you enter
the NO
2
calibration gas concentration.
10.
Set the NO
2
calibration gas concentration to reflect the sum of the
following: the NO
2
concentration generated by GPT, ([NO]
ORIG
-
[NO]
REM
), and any NO
2
impurity.
Use
to move the cursor left and right and use
to increment and decrement the numeric character at the cursor.
F
+
F
+
F
]
NO
[
x
F
+
)
]
[NO
-
]
([NO
=
]
NO
[
D
O
NO
IMP
2
NO
REM
ORIG
OUT
2
Where:
[NO
2
]
OUT
= diluted NO
2
concentration at the output manifold, ppm
[NO]
ORIG
= original NO concentration, prior to addition of O
3
, ppm
[NO]
REM
= NO concentration remaining after addition of O
3
, ppm
11.
Press
to calculate and save the new NO
2
coefficient based on the
entered span concentration.
