Veeco MS40 Operation And Maintenance Manual page 128

should preferably be of all-metal construction, but in any case should not
act as a significant source of adsorbed or absorbed helium.
5.4.2 Spurious Signal Correction
Note: This determination requires the use of the small calibrated leak. If
the calibrated leak has its own integral valve, and the leak and valve are all-
metal construction (except perhaps for the membrane in a membrane-type
leak), Sec. 5.4.2 may be omitted from the procedure.
5.4.2.1
A metal plug is connected to the leak detector
5.4.2.2
The output is zeroed, with the filament on.
5.4.2.3
The leak isolation valve is opened.
5.4.2.4
The pump valve is opened. (Note: For its safety, the filament of the
mass spectrometer tube may be turned off at this point).
5.4.2.5
When the atmospheric air present between the plug and the inlet valve has
been evacuated, the pump valve is closed.
5.4.2.6
The inlet valve is opened promptly, but gradually. The pressure in the
leak detector is allowed to reach a steady value, showing no observable
change in a 1-min period.
5.4.2.7
Turn on filament of mass spectrometer tube if it is not on.
5.4.2.8
When the output has reached a steady value, but in any case not longer
than 3 min after Sec. 5.4.2.6. the output reading is noted. If the leak
detector has been set at reduced sensitivity, the reading should be
converted to equivalent scale divisions for full-sensitivity setting.
5.4.2.9
Close the leak isolation valve as rapidly as feasible.
Vacuum Instrument Corp.
2099 Ninth Avenue
Ronkonkoma, NY 11779
631.737.0900
1109-186-00 Rev. C b-vi