Agilent Technologies 5975C TAD VL MSD, Troubleshooting And Maintenance Manual

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186 5975 Series MSD Troubleshooting and Maintenance Manual
6
Vacuum System
The diffusion pump transports gas by momentum transfer. The heater boils a
special fluid (a polyphenyl ether) inside the stack. As the vapor pressure
increases, the pump fluid vapor is forced out and downward through nozzles
in the stack. The vapor forced out of these nozzles strikes the gas molecules
that are present. This forces the gas molecules down toward the outlet near
the bottom of the pump. Another nozzle in the stack points directly at the
outlet and forces the gas molecules out. The vapor condenses on the sides of
the pump and the liquid drains down to the bottom. The liquid is boiled again
and is reused continuously.
Figure 39 Diffusion pump parts
Foreline gauge assembly
Foreline gauge cable – part of
high vacuum control cable
Diffusion pump outlet
KF10/16 seal
Foreline hose and hose clamp
KF10/16 clamp