Models 947, 948 and 960 Leak Detectors Operations and Service Manual
4-5
4.1 Daily Maintenance
4.1.1 Calibration Check
To perform a calibration check:
1. Press the STD LEAK button.
2. Compare the value displayed on the 947/948/960 to the value of the known calibrated
leak listed on the label on the top of the turret.
Refer to Figure 1-1 on page 1-2 for the location of the label.
3. If the values do not match, press the
AUTO CAL
button and then repeat step 1.
Detailed instructions for sensitivity and calibration checks are included in “Calibration and
Sensitivity Checks” on page 3-11. If specifications cannot be met, Manual Tuning is
required. Manual Tuning is restricted to trained, qualified customer technicians. Contact
Varian Vacuum Technologies Customer Service at 1-800-8VARIAN if manual tuning is
necessary.
4.1.1.1 Leak Checking
The accuracy, reliability, and stability of any mass spectrometer leak detector depends on
the leak-free integrity of its own vacuum system. Inherent helium background and its effect
on sensitivity demands elimination of all detectable leaks. If performance degrades during
operation or after some part of the vacuum system is opened for service, a methodical leak
check eliminates the possibility of a leak as the cause.
NOTE
To ensure reliable testing, after servicing any part of the vacuum
system, the 947/948/960 must be leak checked again.
