Eppendorf Galaxy Gas Analyzer - Manual (Page 42)

Galaxy® Gas Analyzer — Operating manual
42
Tab. 2: User calibration error messages
9.3.1 User calibration explained
User calibration is used for optimizing the performance of the instrument to the current operating
conditions, such as ambient temperature and pressure; as well as correcting for instrument drift
caused by lamp and filter settling.
In general, the instrument should not require calibration more than once a month, but we do
recommend verifying the instruments operation each day.
Zero calibration and Span calibration may be performed individually; however, for a complete
user calibration both must be completed.
(Fig. 28 on p. 43) shows the user calibration curves for factory, zero, and span calibrations.
Factory Calibration (Curve 1)
The Galaxy Gas Analyzer is factory ‘Factory’ calibrated and stable.
Zero Calibration (Curve 2)
This corrects the entire curve for lamp and filter variations caused by aging and user induced drift
due to dirt etc. If done correctly there is often no need to complete a span calibration. However a
poor calibration[A] will result in a span error as shown with the zero indicating a small error [B]
but a significant span error [C].
Span Calibration (Curve 3)
This optimizes the instrument at the span calibration concentration [D] for the current operational
conditions and variations in user calibration gasses. It corrects the span point leaving the zero
unadjusted and should be done at the concentration of normal operation.
Error Probable Remedy
User Zero failed It is quite possible the instrument is trying to zero to a level that is
outside the predetermined range set at the factory when the
instrument was calibrated. To rectify such a problem, first ensure that
the instrument contains none of the gas you were zeroing: flush it
thoroughly with nitrogen. Calibrate the zero again, and if it still fails,
refer to the Reset Factory Settings instructions (see Reset factory
settings on p. 36). If the instrument fails to zero yet again, return it to
the manufacturer for service.
Calibration failed Make sure the span target has been correctly set; if not, correct the
setting. Repeat the entire procedure, including zeroing the channel
and then calibrating the span-make sure the reading is stable before
you span the channel.
Hint!
The Zero calibration is very sensitive and even 100 % instruments will detect in the 0 to 100 ppm
range even though they do not display to this resolution (see Fig. 29 on p. 44).
9
Troubleshooting