Varian 4000 MS, User Manual

Page: 13 / 39

13
Starting the Instrument
Initial Pump down
Check the following:
•
Check the Vacuum connections.
•
Make sure the transfer line is in.
•
Make sure the vent valve is fully closed.
•
Make sure the column is not broken.
Turn on the power at the main power switch; the roughing pump should stop
gurgling after about 10 to 20 seconds.
If the pump continues to gurgle, then do the following.
1. Check that the analyzer assembly is seated properly on the manifold (there
should be no gaps).
2. Check that the transfer line is in.
3. Check that the vent valve is sealed.
Open
System Control
and the
Startup/Shutdown
page opens.
Check the Vacuum Status
The vacuum readings tell a lot about the state of the MS after pump down (and
during operation). Typical operating ranges for the 4000 MS in Internal mode are:
•
Speed 100%
•
Current 200 – 300 mAmps
•
Power 9 – 13 Watts
•
Ion Gauge Pressure < 20
μ
Torr
•
Roughing Line < 50 mTorr
If the Pump Spin Speed does not steadily increase, there may be a leak in the
system. Large leaks are indicated by a turbo speed less than 100%. Small leaks
are indicated by an increase in the pump current after 100% is reached, or in the
ion gauge pressure, see “Diagnostics”. Small leaks are diagnosed by changes in
the ion gauge reading and can be pinpointed using the leak check section in the
method Service.mth. For more detail on troubleshooting leaks, see the
Troubleshooting section in the 4000 GC/MS Hardware Operation Manual.