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Calibration
Multi-Point External
Calibration
4-10
Model 48i Trace Level-Enhanced Instruction Manual
4. Allow the instrument to sample span gas for at least 5 minutes or until
the reading is fully stabilized.
5. Enter the CO calibration gas concentration using the pushbuttons to
adjust the display value to match the cylinder concentration, and then
press
the span gas.
Note that the procedures described above adjust the instrument
readings to match the expected values by resetting the internal zero-
offset and span-factor values. These values are used by the instrument
firmware to convert the raw detector signal to a CO concentration. The
new zero-offset and span-factor values can be seen by selecting
"Calibration Factors" from the Main Menu.
Even if an external calibration curve will be used to interpret monitoring
data, the operator should follow the zero adjust and span adjust instruction
given below. This will bring the instrument's front panel readings into
calibration and simplify general operation and trouble-shooting of the
analyzer.
Zero Adjust
Use the following procedure to set the CO reading to zero.
1. Allow sufficient time for the analyzer to warm up and stabilize.
2. Adjust the gas titration system so CO-free zero air is present in the
manifold.
Since not all flow controllers have a positive shut off, it might be
necessary to disconnect the CO input line and cap it.
3. Allow the analyzer to sample zero air until a stable reading is obtained.
4. Press
5. Allow the instrument another 5 minutes to fully stabilize.
6. In the CO Background screen, press
zero-offset and set the CO reading to zero.
If a strip chart recorder is used to obtain a record of the analog output,
it is recommended that the system be adjusted to obtain a zero trace at
to set the CO reading to match the CO concentration of
and choose Calibration > Cal Background.
to adjust the instrument's
Thermo Fisher Scientific
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Troubleshooting
