[dsg-hallb_htcc] HTCC CO2 pressure

[Marc Mcmullen]

Hi Morgan,

I just looked at the signals, maybe check the bubbler level on the next axis. I see the pressure is very active just under 0.08 iwc ...like its bubbling maybe.

[cid:29cfd96b-0aee-42ca-9608-0165ee5c4d74]

Marc
________________________________
From: Morgan Cook IV <mcookiv at jlab.org>
Sent: Monday, December 13, 2021 9:50 AM
To: Brian Eng <beng at jlab.org>; Youri Sharabian <youris at jlab.org>; Marc Mcmullen <mcmullen at jlab.org>
Cc: Bob Miller <rmiller at jlab.org>; dsg-hallb_htcc at jlab.org <dsg-hallb_htcc at jlab.org>
Subject: Re: HTCC CO2 pressure

So the rotameter is set to 10 lpm; given that it's calibrated for nitrogen or air ( I forget which), it's flowing ~8 lpm of CO2.
The MFC's been set to 7 lpm from the beginning of RGM.
So why is this flow rate of CO2 (15 lpm), the highest flow rate of CO2 that we've ever had, unable to reach, much less maintain a pressure of 0.14 iwc? It's been ~ 0.07 - 0.08 iwc.

The increase to 10 lpm on the MFC only brought the pressure up to 0.08 iwc. Decreasing it to 5 lpm dropped the pressure to 0.07 iwc.

So what's going on? Is the pressure gauge off? Has a leak developed? Has the bubbler shifted? Any ideas?

-Morgan

________________________________
From: Brian Eng <beng at jlab.org>
Sent: Sunday, December 12, 2021 1:25 AM
To: Youri Sharabian <youris at jlab.org>; Marc Mcmullen <mcmullen at jlab.org>
Cc: Bob Miller <rmiller at jlab.org>; Morgan Cook IV <mcookiv at jlab.org>; dsg-hallb_htcc at jlab.org <dsg-hallb_htcc at jlab.org>
Subject: Re: HTCC CO2 pressure

I increased it to 10 lpm: https://logbooks.jlab.org/entry/3961354

This really should have gone via the on-call first rather than through emails though.

________________________________
From: Youri Sharabian <youris at jlab.org>
Sent: Sunday, December 12, 2021 1:02 AM
To: Brian Eng <beng at jlab.org>; Marc Mcmullen <mcmullen at jlab.org>
Cc: Bob Miller <rmiller at jlab.org>; Morgan Cook IV <mcookiv at jlab.org>
Subject: HTCC CO2 pressure

Dear Brian and Marc,

The CO2 gas pressure in the HTCC is fluctuating between 0.04 iwc to 0.09 iwc. The gas flow rate currently is 7 l/min. Usually we use 10 l/min. Please increase the flow rate on the HTCC MFC to 10 l/min.
Usually at 10 l/min we have pressure in the HTCC of about 0.14 iwc to minimize effects of atmospheric pressure changes.
Please let me know if there are any problems.
Thank you.
Regards,
                 Youri

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