5 Operating in EI Mode
Pumping Down
114 5977B Series MSD Operating Manual
Pumping Down
The DS or 8890/7890B GC control panels help you pumpdown the MSD. The
process is primarily automated. After you turn on the MSD by pressing the
On/Off switch, close the analyzer door, and close the vent valve once you hear
hissing (while pressing on the sideplate). The MSD pumps down by itself. The
Agilent MassHunter GC/MS Acquisition software monitors and displays system
status during pumpdown. When the pressure is low enough, the program turns
on the ion source and mass filter heaters and prompts you to turn on the
GC/MSD interface heater. The MSD will shut down if it cannot pumpdown
correctly.
Using the menus or MSD monitors, the DS can display:
• Motor speed for turbo pump MSDs (percent spin speed)
• Foreline pressure for diffusion pump MSDs
• Analyzer chamber pressure (vacuum) for MSDs with the optional G3397B
Micro-Ion Gauge Controller
The 8890 and 7890B GC control panels also display this data.
Controlling Temperatures
MSD temperatures are controlled through the DS. The MSD has independent
heaters and temperature sensors for the ion source and quadrupole mass filter.
You can adjust the setpoints, and view these temperatures from the DS or from
the GC control panel.
Normally, the GC/MSD interface heater is powered and controlled by the Thermal
Aux #2 heated zone of the GC. The GC/MSD interface temperature can be set
and monitored from the DS or from the 7890B GC control panel.
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