INFICON Composer Gas Concentration Controller - Manual (Page 70)

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Composer Operating Manual
3.1.10 What is the Long Term Stability of
this Measurement System
A Composer Transducer was checked weekly for its frequency in nitrogen at
175 Torr (23.3 kPa) and 50 °C. As of this writing there does not appear to be
any trend that might be construed to relate to any wear mechanism or
degradation with time, see
Figure 3-5 . In addition, the short term measurement
stability was checked at the same time and plotted as Root Allan Variance
(RAV). This data is not corrected for zero off sets due to atmospheric pressure
variations over the test period.
Figure 3-5 Long Term Reproducibility and Stability at Low Pressure
Date (1997)
Cell #23: N2 @ 50 sccm, 175 Torr (23.3 KPa), 50º C