2 Operating the MSDTo monitor high vacuum pressure45If the pressure is consistently higher than those listed, refer to the online help inthe MSD ChemStation software for information on troubleshooting air leaks andother vacuum problems.If the pressure rises above approximately 8 × 10-3 Torr, the gauge controllerwill turn off the triode gauge tube. The gauge tube does not turn back onautomatically.Table 2 Typical MSD pressure readings for various helium carrier gas flow ratesDiffusion pump MSDColumn flow (ml/min) Triode gauge reading (Torr) Foreline gauge reading (Torr)1.0 5.0 × 10-5 401.5 7.5 × 10-5 532.0 1.0 × 10-5 66Turbo pump MSDColumn flow (ml/min) Triode gauge reading (Torr)1.0 1.5 × 10-52.0 3.0 × 10-53.0 4.5 × 10-54.0 6.0 × 10-5
