Bruker EPR 12T Cryogen Free, User Manual, Page: 31 / 80

31 ZTKS0213 / Z31939 / Rev.: 01
Operation
5.2.3 Rebuilding Vacuum
Precondition
• Vacuum valve mounted.
Procedure
Figure 5.5: Rebuilding vacuum
1. Use the KF connector to connect the
vacuum pumping unit with the KF
40
flange (5) of the vacuum valve (2). Use a
short pumping line with a large diameter.
2. Evacuate the vacuum valve and the
pumping line to a pressure of better than
5 x 10
-5
mbar.
3. Pull out the valve stem (4) of the valve body
to release the sealing plug out of the top
plate (1). The sealing plug (3) snaps into
place. The snapping is well defined and will
be heard and felt. The cryostat is open after
this procedure.
4. Continue generating vacuum of better than
1 x 10
-4
mbar (up to 2 –3 hours).
5. Start cool down procedure (see section
"Cooling Down" on page 39 ).
6. When the system has reached base temper-
ature push the valve stem (4) slightly into
the valve operator body (2) to insert the
sealing plug (3) into its seat in the top
plate (1). The sealing plug snaps in. The
snapping is well defined and will be heard
and felt.
7. Stop pumping.
8. Vent the pumping line.
9. Disconnect the turbomolecular pump.
10. Remove the vacuum valve (see "Removing
the Vacuum Valve" on page 32 ).