Bruker RS - Warming up from 4.2 K to 300 K

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ZTKS0156 / Z31820 / Rev.: 03
Disassembling
8.2.2 Warming up from 4.2 K to 300 K
Procedure:
1. Check the helium flow during the entire warm up procedure.
2. Check the helium flow systems and the turrets are not blocked with ice formations. If
necessary remove blockage with warm helium gas.
3. If available connect a helium recovery system to the stop valve of the helium flow
system.
4. Close the stop valve at the cold head turret.
5. Switch off the alarm from the External Temperature Control Unit.
6. Switch off the Cryogenic Refrigerator.
i
Do not disconnect any of the Cryogenic Refrigerator parts until the magnet system is at
room temperature.
7. Insert the precooling tube into the helium fill-in turret.
8. Connect a helium gas dewar to the precooling tube. Apply a pressure of < 0.18 bar
to the helium gas dewar.
9. Remove liquid helium by feeding dry helium gas into the precooling tube. Do not
use nitrogen or pressurized air for removing helium out of the helium vessel. This
will lead to ice formation inside the flow systems and the helium vessel. Use dry
helium gas only.
=> Liquid helium will be blown out of the vessel.
10. Check with the precooling tube if liquid helium was left in the helium vessel.
Remove any liquid helium out of the helium vessel.
11. Remount the helium flow system to prevent moisture entering the vessel.