Vacuum Seals; Face Seals; Kf (Nw) Seals - Agilent Technologies 5975C TAD VL MSD Troubleshooting And Maintenance Manual

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Vacuum System

Vacuum Seals

Vacuum seals are shown in
Several types of Viton elastomer O-ring seals are used to prevent air leaks into
the analyzer chamber. All these O-rings, and the surfaces to which they seal,
must be kept clean and protected from nicks and scratches. A single hair,
piece of lint, or scratch can produce a serious vacuum leak. Two of the O-rings
are lightly lubricated with Apiezon-L vacuum grease: the side plate O-ring and
the vent valve O-ring.

Face seals

A face seal is an O-ring that fits in a shallow groove. The sealing surface is
usually a flat plate. The manifold side plate and end plate O-rings fit into
grooves around the large openings in the analyzer chamber. The side plate
swings into place against the side plate O-ring, and must be held in place when
the MSD is turned on for pump down to assure a good seal.
The front and rear end plates are screwed onto the manifold and should not
need to be removed. The GC/MSD interface fastens to the manifold with three
screws.
The calibration valve assembly is fastened onto the front end plate by two
screws. The vent valve knob threads into the front end plate. Small O-rings in
grooves in the front end plate provide vacuum seals.
The diffusion pump baffle adapter has a groove for its O-ring. The baffle
adapter is clamped to the manifold with four claw grips.

KF (NW) seals

Most of the seals for the high vacuum pumps, foreline gauge, and foreline
pump are KF seals. KF seals have an O-ring supported by a centering ring. The
centering ring can be either on the inside or the outside of the O-ring. The
clamp presses two flanges against the O-ring, making a seal. KF clamps must
not be overtightened.
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Figure 38.
5975 Series MSD Troubleshooting and Maintenance Manual