Agilent Technologies MSD 5977B Series Operating Manual page 126

5 Operating in EI Mode
To Monitor High Vacuum Pressure
Table 10 Ion vacuum gauge reading

Column flow rate,
mL/min
0.5
0.7
1
1.2
2
3
4
6
If the pressure is consistently higher than those listed, refer to the online help in
the Agilent MassHunter GC/MS Acquisition software for information on
troubleshooting air leaks and other vacuum problems.
In the Instrument Control view, you can set up an MSD Monitor for displaying this
vacuum reading. The vacuum can also be read on the 8890 or 7890 Series GC
control panel or from the Manual Tune screen.
126
The largest influence on operating pressure in EI mode is the carrier gas
(column) flow. Table 10
gas flows. These pressures are approximate and will vary from instrument
to instrument by as much as 30%.
Optional gauge
reading, Torr
Turbo pump
3.18E–06
4.42E–06
6.26E–06
7.33E–06
1.24E–05
1.86E–05
2.48E–05
3.75E–05
lists typical pressures for various helium carrier

Gauge reading, Torr
Diffusion pump
2.18E–05
2.59E–05
3.66E–05
4.46E–05
7.33E–05
1.13E–04
5977B Series MSD Operating Manual
Foreline reading,
mTorr
Diffusion pump
34.7
39.4
52.86
60.866
91.784
125.76