
77
ZTKS0156 / Z31820 / Rev.: 03
Assembling
4.3.5
Cooling down to 4.2 K
Preconditions
•
Helium vessel filled with cold nitrogen gas.
•
Current lead inserted into the current lead turret.
•
Power supply connected to the current lead.
•
Upper and lower PT 100 temperature sensors show 80 - 90 K.
•
Vacuum pumping unit connected; cryostat evacuated with vacuum less than
5 x 10
-8
bar).
•
Stop valve (3) at the cold head flange connected with the transportation dewar with
warm helium gas.
•
Transportation dewar with sufficient dry and warm helium gas ready.
•
Transportation dewar with sufficient liquid helium ready.
Procedure
1.
Close the vacuum valve (refer to
”Removing the Vacuum Valve” on page 4-53
and remove the vacuum pumping unit from the vacuum valve.
2.
Connect the one way valve (2) at the helium flow system with the vacuum pumping
unit.
3.
Pump and flush the helium vessel with warm helium gas 5 times:
- Fill the helium vessel with dry helium gas until the quench valves open.
- Pump to the following pressures: 0.8, 0.5, 0.3, 0.1, 0.01 bar (11, 7, 4, 1.5, 0.1 PSI).
- Use short pumping times!
4.
Connect the vacuum pumping unit to the vacuum valve and continue to generate
vacuum (refer to
”Generating the Vacuum” on page 4-52
).
5.
Check the zero reading of the helium level sensor.
6.
Insert the magnet side of the helium transfer line completely into the helium fill-in
turret.
Figure 4.80: Helium Flow System during usual operation
1 Connector
2 One way valve
3 Stop valve
4 Cold Head
5 Quench valves
Summary of Contents for RS
Page 1: ...NMR Spectroscopy Service Manual RS ...
Page 4: ...4 ZTKS0156 Z31820 Rev 03 ...
Page 8: ...8 ZTKS0156 Z31820 Rev 03 Table of Contents ...
Page 10: ...10 ZTKS0156 Z31820 Rev 03 Contact ...
Page 14: ...14 ZTKS0156 Z31820 Rev 03 Introduction ...
Page 36: ...36 ZTKS0156 Z31820 Rev 03 Transportation ...
Page 86: ...86 ZTKS0156 Z31820 Rev 03 Operation ...
Page 112: ...112 ZTKS0156 Z31820 Rev 03 Troubleshooting ...
Page 132: ...132 ZTKS0156 Z31820 Rev 03 Disassembling ...
Page 134: ...134 ZTKS0156 Z31820 Rev 03 Appendix ...
Page 136: ...136 ZTKS0156 Z31820 Rev 03 Appendix ...
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