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Calibration
Frequency of Calibration
Calibration Curve
Frequency of
Calibration
Periodic Zero
and Span Checks
Zero Check
4-12
Model 48i Trace Level-Enhanced Instruction Manual
generated, calculate the exact CO concentration using Equation (1).
Record the concentration and the response from the analyzer's analog
output for each concentration.
Plot the analyzer's response versus the corresponding CO concentrations.
Connect the experimental points using a straight line, preferably
determined by linear regression techniques. The calibration curve is used to
interpret, or reduce, subsequent measurement data.
In order to generate data of the highest confidence, it is recommended that
a full calibration be performed:
every three months
●
any time major disassembly of components is performed
●
any time a zero or span check gives results outside the limits described
●
in the site's QA/QC program. Note that the QA/QC limits and
frequency of calibration may also be controlled by regulatory mandates
outside the scope of this manual.
In order to achieve data of the highest confidence, the instrument zero and
span should be checked periodically. These checks can be performed by
challenging the analyzer with zero air and span gas and comparing the
instrument readings to the expected values.
If the span gas has been connected appropriately, the Model 48i Trace
Level-Enhanced's internal CO scrubber and valve system allow the operator
to manually switch the instrument between sample, zero, and span by
simply pushing
appears in the lower left-hand corner of the Run Screen. Repeated presses
of
will cause the instrument to cycle through the three possible
states.
When running the zero check, the instrument should be connected to the
normal inlet system and sampling ambient air. The unit must be allowed to
stabilize for at least five minutes before taking data. If the test data is
recorded directly from the front panel or from the digital interface (RS-
232/485), the drift can simply be reported in units of ppm. If regulatory
requirements call for zero drift to be reported as percent of range, the
calculation will be made based on the range specified in the regulations.
If the data is being collected with a data logger or strip chart recorder
attached to one of the analog outputs, the zero drift is typically reported as
on the front panel. The currently active mode
Thermo Fisher Scientific
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Troubleshooting
