[Hallb-engineering] [New Logentry] Loss of LN2 in the DBX during 80K helium flowing to the Torus

[kashy at jlab.org]

Logentry Text:
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The loss of LN2 (LL8552CP) was due to really poor vacuum in the ESMTL (End Station Magnet Transfer Line) to Hall B. The vacuum was really poor.
When I entered the Hall at 08:00 the TL had sweat on the Vacuum Jacket.

Cyro techs put on a turbo pump at the ESR end of the TL and reported the starting vacuum was on the "one scale".

Approximately 30 minutes later (~10:05 I put a turbo pump on the Hall End of the TL and found the starting vacuum was 240mTorr.
The pump on the Hall B end will continue to run through the weekend.

The safety interlock that are set up to protect the Torus from getting hot gas (close PV8563C if the LN2 reservoir in the DBX empties) did shut the flow to the magnet until the reservoir refilled. (good news)!

PS:
the Solenoid average temperature is 19K
The buffer dewar liquid level is 51%

So 80K circulation to the Solenoid will not be required until next week.
We should pump on and LEAK TEST the Solenoid U-tubes  MONDAY before we start the 80K circulation. And we will need Calvin to bring a Turbo and leak detector to Level 3 of the space frame


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This is a plain text email for clients that cannot display HTML.  The full logentry can be found online at https://logbooks.jlab.org/entry/3857040
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