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The fridge is supposed to have no LHe at the beginning.  The filling should be done once per two days.  You can/should use this preset page to monitor the key parameters.

  1. Change the separator flow to 20 SLM (from 7 SLM usually).

  2. Wait for 1.5-2.0 hours.
  3. Change the separator flow to 25 SLM.
  4. Change the setting of the gate-valve bypass as follows:
    1. The auto control is disabled.
    2. The absolute valve position is 0.05 08 turns.
  5. Enable the interlock with Heat-Ex Top (on Fridge_Valve_Main.vi).

  6. Open the bypass valve at 2.0 turns.  Confirm that the fridge return flow goes up.

  7. Open the bypass valve at 3.0 turns.
  8. Change the separator flow to 30 SLM.

  9. Wait until the Ann-Plate Top resistor goes up to 1400 Ohm, which indicates that the liquid started accumulating.  It usually takes 30 minutes from step #3.  If it takes longer than 40 minutes, search for unexpected conditions.

  10. Wait until the nose LHe level reaches 100%.  It usually takes 15 minutes from the previous step.
  11. Wait until the Heat-Ex Bottom resistor goes down from 1400 Ohm and then up.  It usually takes 10 minutes from the previous step.

  12. Wait until the Heat-Ex Top resistor goes up to 1400 Ohm, which indicates that the liquid is as high as Heat-Ex Top.  It usually takes 10 minutes from the previous step.

  13. Close the bypass valve.

    1. Usually the software interlock sets it at 0.5 turns automatically.
    2. Anyway you set it at 0.0 turns manually.

  14. Change the separator flow to 7 SLM.

  15. Change the setting of the gate-valve bypass as follows:
    1. The set point for the auto control is 40 Torr.
    2. The auto control is enabled.
  16. Make an elog entry to record the time and the mount of this filling.

Old Procedure for Filling the Fridge with LHe (Until November 2023)

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The latest official procedure is posted on DocDB 10375.  The procedure described below is expected to replace (improve) it in future.

The fridge is supposed to have no LHe at the beginning.  The filling should be done once per two days.  You can/should use this preset page to monitor the key parameters.

  1. Change the separator flow to 20 SLM (from 7 SLM usually).

  2. Wait for 1.5-2.0 hours.
  3. Change the separator flow to 25 SLM.

  4. Open the bypass valve at 2.0 turns.  Confirm that the fridge return flow goes up.

  5. Go into the cave to fully open the gate-valve bypass.
  6. Open the bypass valve at 3.0 turns.
  7. Change the separator flow to 30 SLM.

  8. Wait until the Ann-Plate Top resistor goes up to 1400 Ohm, which indicates that the liquid started accumulating.

    1. It usually takes 30 minutes from step #3.  If it takes longer than 40 minutes, search for unexpected conditions.
  9. Wait until the nose LHe level reaches 100%.
    1. It usually takes 15 minutes from the previous step.
  10. Wait until the Heat-Ex Bottom resistor goes down from 1400 Ohm and then up.
    1. It usually takes 10 minutes from the previous step.

  11. Wait until the Heat-Ex Top resistor goes up to 1400 Ohm, which indicates that the liquid is as high as Heat-Ex Top.

    1. It usually takes 10 minutes from the previous step.

  12. Close the bypass valve.

    1. The software interlock (on the Cryo Control Panel) first sets it at 0.5 turns automatically.
    2. You then set it at 0.0 turns manually.

  13. Change the separator flow to 7 SLM.

  14. Go into the cave to partially close the gate-valve bypass.
    1. Move the valve handle until it gently hits its stopper, where a spacer is attached to the stopper so that the gate-valve bypass is closed only partially.
  15. Make an elog entry to record the time and the mount of this filling.

Procedure for Filling the Fridge with LHe to Start the "Standby" Mode

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