Table of Contents
Advertisement
The largest influence on operating pressure in EI mode is the carrier gas
(column) flow.
flows. These pressures are approximate and will vary from instrument to
instrument by as much as 30%.
Table 15
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 Data Acquisition software for information on troubleshooting air leaks
and other vacuum problems.
The vacuum can also be read on the 7890B GC control panel or from the
Manual Tune > Parameters view in OpenLAB.
5975/5977 Series MSD Operation Manual
Table 15
lists typical pressures for various helium carrier gas
Ion vacuum gauge reading
Optional Gauge
reading, Torr
Performance 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
Operating in Electron Ionization (EI) Mode
Gauge reading, Torr
Diffusion pump
2.18E–05
2.59E–05
3.66E–05
4.46E–05
7.33E–05
1.13E–04
3
Foreline reading, mTorr
Diffusion pump
34.7
39.4
52.86
60.866
91.784
125.76
71
Advertisement
Table of Contents
