[Hallb-engineering] [New Logentry] Cryogenic Recovery from ESR Trip

[kashy at jlab.org]

Logentry Text:
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ESR Tripped just before 15:00 and came back on line ~16:00. We found CEV6711B open and the Hall was being swept for controlled access. So we decided to manually close our cold returns on the Torus and Solenoid. This instantly droped the Temperature in the ESR valve box CTD672 as warm flow was not returning to ESR from Hall B. Our Buffer Dewar was returning cold but had 45% level so this was helping to keep the 4K return U-tube at the ESR valve box cold. The Torus and Solenoid went into warm return (cold down mode) they both quickly cooled. The solenoid filled first. The Torus is still filling. Both magnets outlet was cold so we switched both back to cold return at 17:20.

For future trips we should consider closing the Hall B cold return CEV6721B before recovery IF the Torus and or Solenoid go empty of LHe. With current setup the Hall B magnets and dewar should automatically recover and cryo can open the cold return valve CEV6721B when the Hall B on call person verifies that the Torus, Solenoid and Buffer Dewar have Helium levels above 50% and their outlet gas is belo 7K.



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