Situation 1: If the Dewar doesn't contain LHe at the moment

1) Make sure the particular liquefier is on "Manual" mode
2) Close  SVN(A/B) and Pressurize the Dewar up to 8psi.


3) Consider one by one of each tube (at a time) connecting to the level meter (2 copper and 2 plastic) and disconnect each to relieve the gas for a few seconds
4) Make sure to connect all the tubes and leave the needle valves open

Situation 2: If the Dewar contains LHe at the moment

(1) Close A
(2) Disconnect B
(3) flush gHe for few seconds through B
(4) Reconnect B
(5) Open A
(6) Increase pressure to ~15psig
(7) Wait for 10 mins
(8) Close A
(9) Open B to flush again
(10) Opened A while opening B and closed the bottle pressure to see whether gHe coming out from B from the bottom of the dewar

Situation 3: If the solution for Situation (2) doesn't fix the problem

1) Open GV02 (yellow hand valve on QT recovery manifold) a little bit
2) Open VPC and VJV(A/B: depending on which LQ)



3) Regulate GV02 to have no more than 160slm on the HMI-FMR

4) Wait until FMR goes down to lower values (~40-70slm) and check the Dewar pressure is very low (~1 psi).
5) Switch the Liquefier to "Run"+"Manual" mode to warm up


6) Wait for a few hours until the Dewar pressure gets more lower and stabilize.
   If the flow is ~150slm-200slm, then it will roughly take about 12 hours to empty the Dewar.
   To avoid going the LQ to "Alarm" mode, change the Dewar alarm pressure to 0.5 psi (box on the top right corner of the following screenshot).

   

7) Close GV02, then close VPC and close VJV(A/B: relevant LQ).
8) Turn ON cold-head heaters manually to bring the cold-head temperatures to room temperature
    

9) Pressurize the Dewar A/B to 8 psi by opening SV501(A/B) and then setting the flow to 20 slm on FC501BQMC (tap this box and enter 20 on the panel popping up on the lower right and press enter).

     

10) Open VPC,  Open VJV(A/B), Open GV02 to regulate the flow from the Dewar to the tank with ~30 slm.
11) Repeat steps (9) and (10) several times until the cold-head temperatures are at room temp. and also the Dewar pressure holding at 8 psi once pressurized.
12) If the pressure is stable, then consider one by one of each tube (at a time) connecting to the level meter (2 copper and 2 plastic) and disconnect each to relieve the gas for a few seconds while the Dewar pressure is at 8psi (if that's too much we can probably try at a lower Dewar pressure).
13) Make sure that all 4 tubes are reconnected properly, and also make sure that two needle valves close to the Dewar neck are fully opened.
14) Follow the steps on QT System Starting Procedure to get the Liqeufier back to Run+Auto+Liquefy mode.