Varian 4000 GC, Hardware Operation Manual

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Baking Out the Mass Spectrometer
Any time the system is vented you should bake out the system to eliminate water
and contaminants in the vacuum manifold.
The vent knob, CI plunger and surrounding area may be extremely hot,
especially during bakeout. Take appropriate precautions.
To bake out the Mass Spectrometer, proceed as follows:
1. Open the System Control and click on the Temperatures tab dialog.
2. Select
Bakeout
and enter a bakeout time of 2 to 6 hours.
3. Use the following temperatures:
•
Trap at 220 °C or 10 °C higher than the analysis temperature.
•
Transfer line at 280 °C.
•
Manifold at 120 °C.
•
Source at 220 °C.
4. Click on Start Bakeout.
Checking Ion Trap Operation
To check the ion trap operation, proceed as follows:
1. Once bakeout is finished, re-establish the analysis temperature in the trap for
at least 2 hours to achieve thermal equilibrium.
2. The manifold temperature should be at or below 50 °C.
3. Run Auto Tune.
4. Open the Manual Control page and activate the
“C:\VarianWS\4000MSservice\4000 MS Int (or Ext) Service.mth” file.
5. Use the second segment of the method to check the background. Turn on
the ion trap. The ionization time should be above 20,000 μ sec. If the
ionization time is below 20,000 μ sec, continue to bake out the trap or check
the GC for contamination.
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