Operating in Electron Impact (EI) Mode 3
5975 Series MSD Operation Manual for MassHunter 87
7 When prompted, turn the vent valve knob counterclockwise only 3/4 turns
or until you hear the hissing sound of air flowing into the analyzer chamber.
Do not turn the knob too far or the O-ring may fall out of its groove. Be sure
to retighten the knob before pumping down.
Figure 15 Venting the MSD
Vent valve knob
YES NO