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5
Operating in EI Mode
High Vacuum Pressure in EI Mode
106
7000/7010 Series TQ GC/MS Operating Manual
High Vacuum Pressure in EI Mode
The largest influences on operating pressure in EI mode are the carrier gas
(column) and CC gas flows.
lists typical pressures for various helium and
nitrogen CC gas flows. These pressures are approximate and will vary from
instrument to instrument by as much as 30%.
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.
Table 7
Influence of carrier and CC gas flows on ion vacuum gauge readings
CC Gas On
N
2
= 1.5, He = 2.25
CC Gas Off
CC Gas On
N
2
= 1.5, He off
Column Flow
(mL/min)
Rough Vac
High Vac
Rough Vac
High Vac
Rough Vac
High Vac
0.5
1.58 * 10
-1
1.11 * 10
-4
8.82 * 10
-2
6.05 * 10
-7
1.36 * 10
-1
1.31 * 10
-4
0.7
1.61 * 10
-1
1.10 * 10
-4
9.92 * 10
-2
7.75 * 10
-7
1.39 * 10
-1
1.31 * 10
-4
1
1.66 * 10
-1
1.10 * 10
-4
1.00 * 10
-1
8.38 * 10
-7
1.44 * 10
-1
1.31 * 10
-4
1.2
1.69 * 10
-1
1.10 * 10
-4
1.05 * 10
-1
9.38 * 10
-7
1.47 * 10
-1
1.31 * 10
-4
2
1.80 * 10
-1
1.11 * 10
-4
1.22 * 10
-1
1.36 * 10
-6
1.60 * 10
-1
1.32 * 10
-4
3
1.95 * 10
-1
1.12 * 10
-4
1.41 * 10
-1
1.82 * 10
-6
1.75 * 10
-1
1.32 * 10
-4
4
2.10 * 10
-1
1.12 * 10
-4
1.57 * 10
-1
2.33 * 10
-6
1.90 * 10
-1
1.31 * 10
-4
6
2.37 * 10
-1
1.13 * 10
-4
1.89 * 10
-1
3.29 * 10
-6
2.18 * 10
-1
1.34 * 10
-4