Veeco MS40 Operation And Maintenance Manual page 94

Servicing the Gross Valve
(Only on units with the external rough option)
Vacuum Instrument Corp.
2099 Ninth Avenue
Ronkonkoma, NY 11779
631.737.0900
1109-186-00 Rev. C
9. Clean the plunger and the rubber seal with a lint-free cloth. Coat
the face of the seal completely with a very thin covering of vacuum
grease (Dow Corning High Vacuum Grease is recommended). The
coating should be thin enough so that the grease is barely visible
except for leaving a glossy coat on the seat.
10. Replace the spring into the plunger and the plunger into the valve
coil.
11. Coat the O-ring with a thin covering of vacuum grease. Replace the
O-ring into the groove on the valve block.
12. Align the valve assembly with the holes on the valve block (the
electrical connector should be on the right side). Replace the
screws and washers removed in Step 4. Reattach the wires onto
the proper electrical connectors.
1. Vent the entire system. Follow the procedure stated in Section 4.6.
2. Open the rear panel by turning the captive screw at the top of the
panel 1/4 turn counterclockwise and gently lowering the door.
3. The gross valve is labeled and is mounted near the middle of the
valve block. Remove the screws that hold the internal valve
mechanism and the valve restrictor plate. Identify each screw as
they are removed; the two pairs are different in length.
4. While using lint-free gloves, remove the two O-rings with a plastic
tool. Do not use metal or any other hard instruments as they may
scratch the O-ring groove. Wipe each O-ring with a lint-free cloth
and check each carefully for nicks, dents or flat spots. Replace
when necessary.
5. Remove the restrictor plate from the valve. Special attention should
be given to the hole at the mid-point of the restrictor plate. It is
very small and this passage must not be impeded in any way if the
MS-40 is to function properly. Clean the restrictor plate and its
seat with a lint-free cloth. The coating should be thin enough so
that the grease is barely visible except for leaving a glossy coat on
the plate.
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