Agilent Technologies 5975T LTM GC Operation Manual page 77

3
Operating in Electron Impact (EI) Mode
3 Analyzer temperatures and vacuum status are displayed in the Zones field.
Unless you have just begun the pumpdown process, the turbo pump should be
running at least 80% speed. MSD heaters remain off as long as the turbo pump
is operating at less than 80%. Normally, the turbo pump speed will be at 100%.
The MSD heaters turn on at the end of the pumpdown cycle and turn off at the
beginning of the vent cycle. The reported setpoints will not change during
venting or pumpdown, even though both the MSD zones are turned off.
5975T LTM GC/MSD Operation Manual 77