HP 5973 MSD Hardware Manual page 94

Maintenance
This chapter describes maintenance procedures and requirements that are
unique to HP 5973 MSDs equipped with the Chemical Ionization hardware.
Maintenance information in the HP 5973 MSD Hardware Manual still
applies to MSDs equipped with the CI unless it is superseded by information
in this chapter. Be sure to read Before starting in the chapter Maintaining
the MSD of the HP 5973 MSD Hardware Manual (G1099-90001) before
using any of the procedures or information in this chapter.
Maintenance videos on Reference Collection CD-ROM
Most of these maintenance procedures are demonstrated on the multimedia
MSD Reference Collection CD-ROM. Please view these videos.
CI increases the need for ion source cleaning
The primary effect of operating the MSD in CI mode is the need for more
frequent ion source cleaning. In CI operation, the ion source chamber is
subject to more rapid contamination than in EI operation because of the
higher source pressures required for CI.
W A R N I N G
Ammonia CI increases the need for foreline pump maintenance
Ammonia, when used as a reagent gas, it will also change the maintenance
requirements slightly. Ammonia causes the foreline pump oil to break down
more quickly. Therefore, the oil in the foreline vacuum pump must be
checked and replaced more frequently.
Always purge the MSD with methane after flowing ammonia.
Be sure to install the ammonia so the tank is in an upright position. This will
help prevent liquid ammonia from getting into the flow module.
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