[Sbs_gems] [New Comment] GEM Gas weird behavior while on N2

[adr at jlab.org]

Comments:
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 - by adr on Fri, 10/29/2021 - 16:59.

Update - Since this report from Zeke two days ago, now I've been in-person in the gas shed when two bottle changeovers happened.

*Both times, gas seemed to changed over fine automatically. The screenshot of the myaplot around the time of changeover for the second time is attached.
*However, in both times, the alarm started to beep when one cylinder went empty and the system changed over to the other cylinder. Is this supposed to happen? My understanding was that it is supposed alarm only if both bottles went empty.



 - by ewertz on Wed, 10/27/2021 - 19:05.

Hi Jack. Didn't realize those - Hi Jack. Didn't realize those were a lower grade. Will not use for any future use. As far as I can tell the N2 cylinder that was on the right was 'new' in that it was one you recently ordered. I  forgot to talk to you about this, I had used it in a pinch cause there was no other N2 at the gas shed and more N2 had already been ordered to the gas shed. Which would replenish those 2 cylinders. But maybe I don't know the full story there.

 - by segal on Wed, 10/27/2021 - 18:56.

Nitrogen cylinders - Don't use those cylinders. They are Industrial grade. You would want to use the UHP grade, it also comes in a larger cylinder. I'll check a couple things tomorrow. It sounds like there was pre-mix still in the flex hose, but the cylinder was empty.

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Logentry Text:
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So Sean noticed that the gas flow had dropped to zero around 5:45pm. So Anu and I were over in EEL and came over to the Gas Shed. Anu noticed that both N2 tanks were empty. Since there is not a lot of N2 there right now we just put the GEM gas on premixed AR/CO2. We will look into this problem more tomorrow and monitor overnight. From the attached plot it seems like it took from the left N2 bottle all of today fine. Then it 'switched' over to the right bottle and the gas ran out very quickly on the order of 5-10 minutes. We are not sure why this occurred. But we connected it up to the right cylinder after clearing the alarms and this did not occur again. For context Ch_32 is the left cylinder and Ch_33 is the right cylinder. These were smaller cylinders so Anu suspects they had overall less gas compared to the 'normal' larger ones, but that still does not explain the behavior of the right cylinder at changeover<br>


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