Varian 4000 GCMS, Installation Procedures Manual

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Section 3. Preliminary Tuning
Before preliminary tuning, be sure the MS has returned to Analysis
temperatures and the GC column flow rate is set to 1 mL/min.
3.1 System Monitoring
After bakeout, go to Startup/Shut Down (shown in Figure 2.1) and monitor the
following:
•
Heated Zones
: Operating Conditions should be close to Current Set
Points.
•
Vacuum System: Status should be Ready, Pump Spin Speed should be
100%, Current should be significantly less than 300 mAmps, dependent
on damping gas flow rate.
•
Pneumatics (external mode only): Damping Gas On, Flow Rate 1.0 - 4.0
mL/min (should match the set point).
•
Getter Co
ntrol
: Heater On, Temperature > 300 °C
Next, go to Diagnostics, select the Ion Source, Multiplier/Dynode, and Ion Gauge
check boxes (refer to Figure 3.1) and monitor the following:
•
Vacuum System
: Power should be 8-12 Watts with no damping gas,
12-15 Watts with damping gas flow.
•
Ion Gauge
: Pressure should read back a µTorr value that will vary
dependent on column flow, damping gas flow, air/water levels, etc. This
is the manifold pressure.
•
Trap
: Multiplier voltage operating condition should be displayed, Dynode
should be approximately 10,000V.
•
Ion Source ( external mode )
: operating conditions should be displayed,
check for no read backs equal to zero. (NOTE: un-checking the Ion
Source box should cause Emission to read back < 5 µAmps or there
may be a current leakage issue indicating a need to clean the filament
and lens areas.)
•
Roughing Line Pressure
: should be significantly <100 mTorr.
•
Deviation
: should be less than 3 µA after auto tuning the electron and ion
lenses.