Introduction 1
5977B Series MSD Troubleshooting and Maintenance Manual 25
Precautions
Take the following precautions when operating a GC/MSD system with
hydrogen carrier gas.
Equipment precaution
You MUST ensure the front side-plate thumbscrew is fastened finger-tight. Do
not overtighten the thumbscrew; it can cause air leaks.
You must remove the analyzer window cover on the front of a 5977B HES MSD.
In the unlikely event of an explosion, this cover may dislodge.
Power failure If the power fails, both the GC and mass
spectrometer shut down. The carrier gas, however,
is not necessarily shut down. As described
previously, in some GCs a power failure may cause
the carrier gas flow to be set to maximum. As a
result, hydrogen may accumulate in the mass
spectrometer.
Tab le 4 Hydrogen accumulation mechanisms (continued)
Mechanism Results
Once hydrogen has accumulated in a mass spectrometer, extreme caution must be
used when removing it. Incorrect startup of a mass spectrometer filled with
hydrogen can cause an explosion.
After a power failure, the mass spectrometer may start up and begin the pumpdown
process by itself. This does not guarantee that all hydrogen has been removed from
the system, or that the explosion hazard has been removed.
Failure to secure your MSD as described above greatly increases the chance of
personal injury in the event of an explosion.
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