HP 5973 - Page 45

2 Operating the MSD
To monitor high vacuum pressure
45
If the pressure is consistently higher than those listed, refer to the online help in
the MSD ChemStation software for information on troubleshooting air leaks and
other vacuum problems.
If the pressure rises above approximately 8 × 10
-3
Torr, the gauge controller
will turn off the triode gauge tube. The gauge tube does not turn back on
automatically.
Table 2 Typical MSD pressure readings for various helium carrier gas flow rates
Diffusion pump MSD
Column flow (ml/min) Triode gauge reading (Torr) Foreline gauge reading (Torr)
1.0 5.0 × 10
-
5
40
1.5 7.5 × 10
-
5
53
2.0 1.0 × 10
-
5
66
Turbo pump MSD
Column flow (ml/min) Triode gauge reading (Torr)
1.0 1.5 × 10
-
5
2.0 3.0 × 10
-
5
3.0 4.5 × 10
-
5
4.0 6.0 × 10
-
5