next up previous contents
Up: 7.2 High Vacuum Leaks Previous: 7.2.2 Large High Vacuum   Contents

7.2.3 Small High Vacuum Leaks

If the MS can be turned ON safely, the MS itself can be used as a 'leak detector.' In ChemStation, go to MS Manual Tune, Edit MS Parameters. You may want to set the scan range to just around the signals expected for the detection gas. For example, if using Argon (atomic mass 40 amu), you could use a scan range of 10-50 amu. You do not need calibration gas for this procedure, so do not open the calibration gas valve. Set the MS to SCAN. Spray the detection gas in small areas while watching the ChemStation Monitor. A rapid increase in signal at mass(es) in the mass spectrum of the detection gas will be observed when the leak is sprayed.

John S. Riley, DSB Scientific Consulting