[Hallb-engineering] [New Logentry] Hall B ESMTL (transferline from ESR to the Hall) vacuum

kashy at jlab.org kashy at jlab.org
Mon Mar 12 18:10:02 EDT 2018

Logentry Text:
At 15:20 C. Perry of cryo contacted me and said there was ice forming on the VJ of the ESMTL as it exited the ground and he suspected bad vacuum. I went out to check and indeed it was correct.
The VJ in the Hall felt cool to the touch and at the vacuum break ring there was a small ring of ice. Chris and I went into the Hall and connected a Turbo pump to a CVI port. We pumped the vacuum in the hose and then valved off the pump. Upon opening the CVI to the system the vacuum in the hose went to 1.45Torr. I started the turbo and it ramped up to full speed. The convectron gage dropped to 26mTorr by the time the turbo pump hit full speed (660Hz) its an 8" turbo but pumping through ~6 ft of 1.5"OD flex hose. Pressure on the turbo pump controller read 3.4E-3mBar. 

This is not the ideal place to pump because the vacuum space inside the shield circuit is only common with the vacuum space outside the shield circuit at the ESR end (~160ft away). 

The ice ball in the Hall is melting and the dripping water is going into a bucket.


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/3544240
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