Varian 979 Series, Operation Manual

Page: 43 / 140

2-1
Model 979 Series Helium Mass Spectrometer Leak Detector
DRAFT 9/15/03
Section 2. Operating the 979 Leak Detector
2.1 Initial Startup and Shutdown
2.1.1 Startup
Plug the leak detector power cord into an appropriate receptacle and place the power
switch on the rear power control panel in the
l position.
When the SYSTEM READY indication appears on the home screen, the leak detector is
ready for operation. If the 979 is being started after a long period of being off (several hours),
it may take up to 30 minutes to stabilize and provide reliable, quantitative leak rate
readings.
2.1.2 Calibration
The 979 is capable of performing an automated calibration routine using either an internal
calibrated leak (factory installed), or an external calibrated leak placed into the test port.
Refer to Section 2.6.1 “Calibrated Leak Set-Up” on page 2-14 for proper set-up of the 979
for auto-calibration.
After starting the 979, a calibration routine must be executed. If using the internal calibrated
leak, a calibration is performed by pressing the TEST button on the front panel to place the
system in test mode, then pressing the CALIBRATE button on the front panel to perform an
automated calibration of the system.
Calibration can be verified by pressing the READ STANDARD LEAK button on the front
panel when in TEST mode. Press the READ STANDARD LEAK button again to return to TEST
mode.
If an external leak is to be used, first press the VENT button to vent the leak detector and
then install a calibrated leak into the test port. Press the TEST button to place the leak
detector in Fine Test mode. Verify the correct leak rate value for the external leak by going to
the Calibrated Leak Set-Up screen (Section 2.6.1 “Calibrated Leak Set-Up” on page 2-14).
Once in Fine Test, press the CALIBRATE button to perform an automated calibration.
When calibration is complete, the leak detector reverts to a Fine Test mode of operation to
allow for calibration verification.
2.1.3 Shutdown
Shutting down the 979 is as simple as moving the power switch on the rear panel to
the
°
position. The system may be in any mode when shut down. It bears noting, however,
that when the system is shut down, all valves in the system close, so if the system is not in
VENT mode, the test port remains under vacuum and may be difficult to open.