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Section 2.4
Reinstalling the Cryopump
2.3
Chapter 2
Installation and Removal
Removing the Cryopump
Always wear protective clothing, including thermal gloves, eye protection,
and covered shoes, when you install or remove the cryopump from the dewar
or when you work with liquid helium, liquid nitrogen, or any other cryogen.
For more information about cryogenic safety, refer to the Physical Property
Measurement System: Hardware Manual.
Warning!
Complete the following steps to remove the cryopump from the PPMS and reinstall the standard PPMS
top plate assembly.
1.
Set the PPMS system temperature to 320 K.
2.
Locate the blank plate, the PPMS top plate assembly, and the sheet metal housing for the PPMS
top plate assembly. These components should be in the cryopump accessories box.
3.
Use a 5/32-inch hex Allen key to unscrew the four 10-32 screws from the cryopump manifold.
Keep the screws in a safe place; you use them to reinstall the standard PPMS top plate.
4.
Vent the system continuously.
5.
Remove the screws in the cryopump sheet metal side panels, and then remove the side panels.
6.
Remove any inserted probe or baffle set.
7.
Slowly pull the entire cryopump assembly straight up and out of the cold bath. Removing the
cryopump slowly helps avoid damaging it by allowing it to heat up from the top slowly, thus
boiling off any nitrogen condensed inside the cryopump.
Do not move the cryopump any angle or the tube will bend. Sometimes the oring may freeze as you lift the cryopump straight out of the dewar, and the tube
will stick. If this occurs, do not force the pump to move as it may jolt upward,
and you may hurt yourself and damage the tube. Wait approximately one
minute until the pump can move freely, then continue to lift it straight out.
Caution!
8.
Let the cryopump warm to room temperature.
9.
Insert the blank plate (part number 4078-092) into the dewar opening. Refer to figure 2-7.
10. Install the standard PPMS top plate assembly. Use the four screws to attach the top plate
assembly to the PPMS probe.
11. Disconnect the sample chamber pumpout line from the cryopump and plug it into the standard
port on the back of the PPMS probe head. You must remove the sample space plug (part number
4083-059) to do this.
NOTE
If the cryopump will be out of the sample chamber for a brief time⎯for
example, if you are only going to perform a warm regeneration⎯steps 12
and 13 are unnecessary.
12. Use the Model 6000 CONFIG menu to tell the Model 6000 that the cryopump is removed.
Do the following: (a) select CONFIG >> Hardware >> High Vacuum; (b) under Type of
System option, select None; and then (c) press <Alt+Enter> to save the change.
2-14
PPMS Cryopump User’s Manual, Rev. C-2
June 2005
Quantum Design