Procedure for Filling the Fridge with LHe and Pausing the Fill

It is to prepare for the shielding block installation conducted in the week of 2022-12-19 (Mo).

1. Stop the automated control.
   1. Sit in front of the target computer and open "Fridge_Valve_Main.vi" (if not opened) by pressing the "Open" button at the right side of Cryo Control Panel.
   2. Confirm that the automated control of the bypass valve is running.  If not, this procedure might not be applicable.
   3. Disable the automated control, by clicking the toggle switch labelled "Automated Bypass-Valve Control".
2. Fill the fridge with LHe.
   1. Disable the SMS (Discord) alarm, by clicking the toggle switch labelled "SMS".
   2. Click the up (or down) arrow of the "Set Turns" box multiple times so as to set the turn to "1.0".
   3. Confirm that the Main Return flow increases on the right-side strip chart in this page;  https://e906-gat1.fnal.gov/data-summary/e1039/target-par-preset/return_flow.php
   4. Increase the turn step-by-step (wait for 20 seconds per +0.1 turns), until the Main Return flow reaches about 30-50 SLM.  Usually the turn should be 1.2-1.4.
   5. Wait until the nose LHe level becomes 100%.
      • If the change is too slow, you can increase the flow upto 100 SLM, with closer attention.
   6. Start watching the fridge temperatures on the left-side strip chart opened above.
   7. Wait until the "Heat-Ex Top" temperature goes above 1,400 Ohm.  Note that the change is sudden.  Be prepared to make the next step immediately.
   8. Set the turn to "0", by clicking the down arrow or entering "0" in the "Set Turns" box.
   9. Confirm that the Main Return flow becomes ~5 SLM or less.
3. Pause the fill.
   1. Click the toggle switch labelled "Motor Power" under "Bypass Valve".  The switch moves downward and its color changes from green to gray.
   2. Go into the cave.
   3. Try to close the bypass valve by hand.  It should be already fully closed.  If not, record how many turns did you make.
   4. Try to close the run valve by hand.  It should be kept closed now.  If not, record how many turns did you make.
   5. Change the Separator Return flow from 12 to 8 SLM (try 10 SLM on 2022-12-22), using "THCD_401_Main.vi".

Notes:

• In case of trouble, you should fully close the bypass valve remotely (i.e. VI) or manually.  To do that manually, the motor power has to be disabled on VI, or remove the motor from the valve shaft.  A black Allen wrench is taped on the motor support.

Procedure for Resuming the Fill

1. Change the Separator Return flow from 8 to 12 SLM, using "THCD_401_Main.vi".
2. Go into the cave to confirm that the run and bypass valves are fully closed.  If not, report it on Discord to find why/when/whom they were opened.
3. Click the toggle switch labelled "Motor Power" under "Bypass Valve", to enable the motor power.  If it was already enabled, report it on Discord.
4. Wait for 5 minutes.
   1. This step is to accumulate LHe in the separator.
5. Fill the nose with LHe manually.  Can skip this step if the nose LHe level is already high, >70%.
   
   1. Click the up (or down) arrow of the "Set Turns" box multiple times so as to set the turn to "1.0".
   2. Confirm that the Main Return flow increases on the right-side strip chart in this page;  https://e906-gat1.fnal.gov/data-summary/e1039/target-par-preset/return_flow.php
   3. Increase the turn step-by-step (wait for 20 seconds per +0.1 turns), until the Main Return flow reaches about 30-50 SLM.  Usually the turn should be 1.2-1.4. 
   4. Wait until the nose LHe level becomes 80%.  A higher level (80-100%) is acceptable, but never keep filling above 100%.
      1. If the level does not start going up in 5 minutes; close the valve, wait for 10 minutes, and try again.
   5. Close the bypass valve, by setting the turn to "0".
   6. Confirm that the Main Return flow is ~5 SLM or less, and the nose LHe level is going down slowly.
6. Enable the automated control of the bypass valve.
   
   1. Confirm that the "Set Point of He Level" is 75%.
   2. Click the toggle switch labelled "Automated Bypass-Valve Control".
   3. Enable the SMS (Discord) alarm, by clicking the toggle switch labelled "SMS".
   4. Report on Discord that the automated control has started.  Kenichi has to check the behavior at the beginning.