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Calibration
Calibration in Dual Range and Auto Range Mode
Thermo Scientific
42iQD Instruction Manual
4-15
The dual/auto range calibration feature is used to calibrate the analyzer at
two different span levels (as opposed to a single span level in the standard
mode) generating a “tailored multi-point” calibration curve stored in the
analyzer's memory. This feature may be used:
●
When widely different gas levels are being monitored, such as a factor
of 10 or greater apart
●
If precision and span levels are being introduced using separate tanks
●
If more than one multi-component cylinder is being used to calibrate
the instrument
Properly designed chemiluminescence analyzers are inherently linear over a
wide dynamic range; and under normal U.S. EPA compliance situations
this feature is not required. Dual calibration may be used for span levels less
than a factor of 10 apart, however if this is done to correct for a significant
non-linearity, it may mask the problems causing the effect, such as, bad
calibration cylinder, leaks in sampling lines, or low ozonator output.
Use the following procedure to set the NO
x
background to zero.
For detailed information about the menu parameters and the icons used in
these procedures, see the “
” chapter.
1.
Follow the “
” procedure described previously in this
chapter.
2.
Be sure the instrument is in the auto or dual mode. If the instrument is
not in auto or dual mode:
a.
From the Home screen choose
Settings>Measurement
Settings>Range Mode Selection
.
b.
Select
Auto
or
Dual
mode.
3.
Introduce zero air to the SAMPLE bulkhead and allow the analyzer to
sample zero air until the NO
x
response stabilizes.
4.
After the response is stabilized, from the Home Screen, choose
Calibration>Calibrate Backgrounds>Calibrate NO
x
Background
.
The Target NO
x
Concentration button will read 0.000. The Calculated
NO
x
Background button will display the background needed to make
the current NO
x
concentration go to 0.000.
Calibration in Dual
Range and Auto
Range Mode
Set NO
x
Background to
Zero
Summary of Contents for 42iQD
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