98 Troubleshooting and Maintenance Manual
6 Vacuum System
Common Vacuum System Problems
Air leak symptoms
The most common problems associated with any vacuum system are air leaks.
Symptoms of air leaks include:
• Loud gurgling noise from the foreline pump (very large leak)
• Inability of the turbo pumps to reach 95% speed
• Higher than normal high-vacuum gauge controller readings
The instrument will not pump down successfully unless you press on the side
board (analyzer door) when you turn on the MS power. Continue to press until
the sound from the foreline pump becomes quieter.
Pumpdown failure shutdown
The system will shut down both the high-vacuum and the foreline pump if the
system fails to pump down correctly. It takes approximately 10 minutes for the
foreline pump to achieve 10 Torr, which then allows the turbo pumps to start.
If a turbo pump speed is below 80% after an additional 10 minutes, the system
shuts down.
This is usually because of a large air leak: either the side plate has not sealed
correctly or the electronic vent valve is still open.
To restart the MS, find and correct the air leak, then switch the power off and
on. Be sure to press on the side plates when turning on the MS power to
ensure good seals.
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