[Sbs_gems] [New Logentry] Plan to gas system

[chandan at jlab.org]

Logentry Text:
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On 25th June, one of the nitrogen lines used for the CO2 bottle switch-over developed a leak (most likely due to its age and heat. This leak was similar to the one shown in the entry -https://logbooks.jlab.org/entry/4310368).
These lines are inside the SBS gas shed. Due to its location, the CO2 side of the lines gets a few hours of sunlight. Most likely, that was the cause of the damage and development of the leak.

On Wednesday, we replaced all three N2 lines used to control the CO2 bottle switch-over. The pipes for the Ar-side were checked and the pipes looked okay.
We set up new lines to supply nitrogen gas from a liquid nitrogen dewar for both SBS and BB sides. We discussed last year to use boil-off nitrogen to flush the chambers and the experts were okay with that.

I talked with Mark and Dave Gaskell, and both of them were okay with this modification. Now, we are ready to start flowing the boil-off gas from dewar.
However, we are waiting to check whether the replaced MFC (on the Ar line) solved the long-standing issue of dropping Ar contained in the mixture during the Ar-bottle changeover.
So far one bottle changeover happened and we haven't seen any drop of Ar contained during the changeover. We would like to see a couple of more bottle changeovers before declaring victory.

Next week, I'll be on leave. I informed Lars and am requesting the GEM experts to keep an eye on the GEM gas system. 
We will start flowing boil-off nitrogen from July 8, if that is okay with the GEM experts. Please let me know if you have any suggestions/comments on this plan.

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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/4311611
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