Teledyne Mixchek - Helium / Oxygen mixture analyzer - Manual (Page 21)

MIXCHEK Setup
Teledyne Analytical Instruments 21
Figure 2-6: Battery Installation
2.7 Calibration
The analyzer is supplied fully calibrated from the factory but will
require calibration checks and recalibration every 30 days or less to
maintain the best accuracy.
Note: The sample gas must be flowing to accurately calibrate the
oxygen analyzer. You may find that when the sample gas
is not flowing the oxygen reading drops slightly. This is due
to the oxygen sensor consuming the oxygen inside the
sample block thereby reducing the oxygen level.
The oxygen cell has zero output when there is no oxygen present
therefore the oxygen channel is automatically zeroed. For span
calibration, it is usually more convenient to calibrate the oxygen
analyzer with compressed air from a cylinder. Air has oxygen content of
20.9%. To calibrate the oxygen cell, the sample flow rate should be set
to 0.2
- 2LPM. The air is then attached to the sample line. After the
reading stabilizes, adjust the oxygen reading to 20.9% with the Span