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Portable Trace Oxygen Analyzer Installation
Teledyne Analytical Instruments 21
2.4 Calibration
Calibration involves using a span gas to set the span of the
instrument. The proper span gas concentration depends on the range that
the instrument will be used on. The correct concentration should be 80-
90% of the range used. For instance, if the analyzer is to be used on a
range of 0-150 ppm oxygen, then a span gas should be prepared with
120-135 ppm oxygen in nitrogen.
2.4.1 Calibration Procedure for Trace Analysis
To calibrate the Model 3110, the instrument must be fitted with a
trace sensor. The instrument must also be purged overnight using a zero
gas (a pure gas with no oxygen, typically O
2
free N
2
) before calibrating.
For A-2C type cells, match the CO2 content in the span gas to that of the
sample gas.
To calibrate the analyzer for trace analysis:
1. Purge the analyzer overnight.
2. Purge the calibration gas sample line, regulator, and control
valve. See Section 2.4.3.
3. Set the calibration gas flow rate to 1 SCFH.
4. Attach the vent line followed by the span gas line using the
quick disconnect fittings.
5. Navigate to the SPAN VALUE screen (see Section 3.2.13)
and set the span value to the known oxygen concentration in
ppm of the span gas.
6. Observe the oxygen reading on the screen to determine when
the reading has stabilized.
7. Navigate to the SPAN screen and select SPAN: START.
8. When the screen changes and displays SPAN: FINISH, select
SPAN: FINISH to set the span.
9. Allow the span gas to flow for several minutes to verify the
proper span setting.
10. Calibration is complete. Remove the span gas line first
followed by the vent line.