[dsg-hallb_htcc] Fw: HTCC gas pressure

[Brian Eng]

Youri,

I've forwarded this email to the mailing list so we can get some more eyes on it.

The issues with the instability recently are due to ambient pressure changes (see the HTCC recent.png image). While the ambient pressure normally does fluctuate, it doesn't normally fluctuate so much within those changes, which is why the pink line is "bolder" for the past few days. I'm not sure what there is to do about this other than flowing even more and forcing it to bubble constantly.

Another thing I noticed is that the detector pressure is lower than it used to be (see the HTCC history.png image). I don't know if this was a simple oil level change and is expected or if maybe there is a leak somewhere so the amount being flown isn't actually getting to the detector (or even the detector itself leaking). Also since there is a rotameter in parallel there is additional flow that can't be tracked.

As far as the gas system itself it's doing what it's being asked.

________________________________
From: Youri Sharabian <youris at jlab.org>
Sent: Monday, January 3, 2022 10:15 AM
To: Brian Eng <beng at jlab.org>; Marc Mcmullen <mcmullen at jlab.org>
Cc: Denny Insley <dinsley at jlab.org>
Subject: HTCC gas pressure

Dear Brian and Marc,

Last several days I am receiving HTCC minor pressure alarm notifications on my cellphone. Yesterday on Jan 2 I have increased CO2 gas flow rate on the rotameter from 7-8 l/min to 10 l/min in order to reduce sensitivity of the detector to fluctuations of atmospheric pressure. But the gas.stp Graph shows very large fluctuations of the differential pressure in the detector (from 0.1 iwc to 0.04 iwc) which I consider as unusual although weather currently is also very unstable. But the pressure changes are very large and rapid.
Please, I would like to ask you to look at the data including for last couple of days and let me know your opinion on explanation what is going on in general.
Today during regular Hall B meeting I have reported my observations regarding HTCC gas pressure problems. I have suggested that we need to run tests to find possible gas leaks and also check performance of regarding pressure sensors. I asked Denny Insley to meet to decide what needs to be done in the hall. Of course without your opinion not much can be done at all. I am ready to meet withyou in your office at any time to get help from you. I think that would be very important to understand what needs to be done.
Thank you very much for your response in advance.
Best regards,
                       Youri

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