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NO, NO
, and Prereactor
x
Backgrounds
Thermo Fisher Scientific
CALIBRATION FACTORS:
>NO BKG
NOx BKG
PREREACTOR BKG
NO COEF
NO2 COEF
NOx COEF
CAL PRESSURE
RANGE
AVG
DIAGS ALARM
RESET USER CAL DEFAULTS
The NO, NO
during zero calibration. The NO background is the amount of signal read
by the analyzer in the NO channel while sampling zero air. The NO
background is the amount of signal read by the analyzer in the NO
channel while sampling zero air. The Prereactor background is the amount
of signal read by the analyzer when the sample is routed through the
prereactor. The background signal is the combination of electrical offsets,
PMT dark currents, and trace substances undergoing chemiluminescence.
Before the analyzer sets the NO, NO
stores these values as the NO, NO
respectively. The NO
and NO
corrections are typically below 1.5 ppb.
The NO, NO
manual zero calibration of the instrument. Before performing a zero
calibration, allow the analyzer to sample zero air until stable readings are
obtained. The NO channel should be calibrated first. The NO, NO
Prereactor Background screens operate the same way. Therefore, the
following description of the NO background applies to the NO
Prereactor background screens as well. The first line of the display shows
the current NO reading. The second line of the display shows the NO
background correction that is stored in memory. The NO background
correction is a value, expressed in the current gas units, that is subtracted
from the NO reading to produce the NO reading that is displayed.
In the example below, the analyzer is displayed 0.09 ppb of NO while
sampling zero air. A background correction is 0.0 ppb means that 0 ppb is
being subtracted from the NO concentration being displayed. Therefore,
the background correction must be increased to 0.09 ppb in order for the
0.0
0.0
0.0
1.000
1.000
1.000
150.0 mmHg
and Prereactor background corrections are determined
x
background correction is determined from the NO
2
background corrections and is not displayed. The background
x
and Prereactor Background screens are used to perform a
x
CALIBRATION FACTORS:
>NO BKG
NOx BKG
PREREACTOR BKG
HI NO COEF
HI NO2 COEF
HI NOx COEF
LO NO COEF
RANGE
AVG
DIAGS ALARM
LO NO2 COEF
LO NOx COEF
CAL PRESSURE
RESET USER CAL DEFAULTS
and Prereactor readings to zero, it
x
, and Prereactor background corrections,
x
Model 42i Trace Level Instruction Manual
Operation
Calibration Factors Menu
0.0
0.0
0.0
1.000
1.000
1.000
1.000
1.000
1.000
150.0 mmHg
x
x
, and
x
and
x
3-17
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