16 Troubleshooting and Maintenance Manual
1 Introduction
• Accumulation of hydrogen in the GC oven and subsequent combustion (See
your GC documentation and the label on the top edge of the GC oven door.)
• Accumulation of hydrogen in the MS and subsequent combustion
Hydrogen accumulation in an MS
All users should be aware of the mechanisms by which hydrogen can
accumulate (Table 2) and know what precautions to take if they are certain or
suspect that hydrogen has accumulated. Note that these mechanisms apply to
all mass spectrometers.
The MS cannot detect leaks in inlet and/or detector gas streams. For this reason, it
is vital that column fittings should always be either connected to a column or have a
cap or plug installed.
Table 2 Hydrogen accumulation mechanisms
Mechanism Results
Mass spectrometer turned off A mass spectrometer can be shut down
deliberately. It can also be shut down accidentally
by an internal or external failure. A mass
spectrometer shutdown does not shut off the flow
of carrier gas. As a result, hydrogen may slowly
accumulate in the mass spectrometer.
Mass spectrometer automated shutoff
valves closed
The mass spectrometers are equipped with
automated shutoff valves for the calibration vial
and the reagent gases. Deliberate operator action
or various failures can cause the shutoff valves to
close. Shutoff valve closure does not shut off the
flow of carrier gas. As a result, hydrogen may
slowly accumulate in the mass spectrometer.
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