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Evacuate LHe Transfer Tube

The LHe transfer tube contains a vacuum jacket that needs to be re-evacuated occasionally to maintain proper insulation of the liquid helium during transfers. To preserve the vacuum of the transfer tube, you will use the turbo pump. When setting up the transfer tube vacuum jacket to be pumped, you will be disconnecting and moving around metal hoses. You MUST make sure the ends of these hoses are protected with plastic caps.

  1. Make sure the IVC is isolated.
  2. Make sure the pumping station, leak checker and scroll pump are off and isolated.
  3. Turn on the pumping station by pressing the green button. It takes ~20 minutes for the turbopump to wind up to full speed, so as soon as possible press the rightmost button to start up the turbo.
  4. Disconnect from the leak checker the metal hose that connects to it from the pumping station.
  5. From the red toolbox on top of the black tool cabinet, find a KF25 to KF16 adapter and attach it to the open end of hose from the pumping station.
  6. Connect the KF16 port on the transfer tube to the KF16 flange leading to the pumping station.
  7. Plug in the scroll pump to turn it on, then open the valves between the scroll pump and the transfer tube. Finally, remove the cap covering the black valve on the transfer tube, and open that valve.
  8. Pump with the scroll pump until the pressure in the transfer tube vacuum jacket reaches <4E-2mbar.
  9. If the turbopump is up to full speed, open the valve leading to the turbopump to begin pumping on the vacuum jacket with the turbopump - the pressure should begin to decrease quickly.
  10. Once the turbopump valve is completely open, close the valve leading to the scroll pump and unplug the scroll pump.
  11. Pump for a few hours. You can check the pressure gauge, but if hasn't gone below 4E-3 mbar, then there is either a leak or the gauge is broken.
  12. When you are done pumping on the transfer tube vacuum jacket, isolate the jacket by closing the black valve on the transfer tube.
  13. Isolate the turbo pump by closing the black valve right above the pump. Close the following black valve along the metal hose. This will isolate the line leading to the IVC.
  14. Unfasten the metal hose from the transfer tube and remove the adapter from the end of the metal hose. Reconnect the leak checker to the pumping manifold.