4
Operating in EI Mode
Figure 31
Table 9
Column flow rate,
mL/min
0.5
0.7
1
1.2
2
3
4
6
102
Manual Tune Values tab HiVac reading
The largest influence on operating pressure in EI mode is the carrier gas
(column) flow.
Table 9
flows. These pressures are approximate and will vary from instrument to
instrument by as much as 30%.
Ion vacuum gauge reading
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 gas
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