Veeco MS40, Operation And Maintenance Manual, Page: 51 / 169

Vacuum Instrument Corp.
2099 Ninth Avenue
Ronkonkoma, NY 11779
631.737.0900
Calibration Check (Cal-Check)
Cal-Check is the feature that allows the user to verify the measurement
accuracy of the MS-40 leak detector. The unit automatically connects the
internal leak rate standard of the unit to the test port, measures the internal
calibrator, subtracts the background helium measurement and displays the
results on the Leak Rate Bar Graph located on the User Panel. The Cal-
Check function is activated by pressing the CAL CHECK momentary
switch on the Service Panel.
When the indicator on the Cal Check momentary switch begins flashing,
the MS-40 has completed its measurement cycle and the Cal-Check
reading from the User Panel should now be compared to the display on
the Service Panel. The alphanumeric display of the Service Panel
indicates the calculated temperature compensated value of the internal
leak rate standard. The leak rate bar graph indicates the measured value
of the internal calibrator.
The unit is considered to be measuring accurately whenever the two
readings are within 10% of each other. If the difference between the two
readings is greater than 10%, the measurement gain may be adjusted by
pressing the CAL (Calibrate) button (see below) or the leak detector may
be retuned and re-calibrated by pressing the TUNE button (again, see
below). If the two readings are within 10%, pressing the Cal Check
momentary switch ends the Cal-Check cycle.
NOTE:
During the warm-up period of the unit (approximately
one-half hour), the leak detector’s calibration will not
be as accurate as during normal operation. When
using the MS-40 during warm-up, perform the Cal-
Check function to ensure the integrity of the unit’s
measurement accuracy.
1109-186-00 Rev. C 2-34