[dsg-hallb_dc] DC CO2 mix 2?

[Morgan Cook IV]

well, hopefully it survives the weekend. Thanks.

Y'all have a good weekend
________________________________
From: Brian Eng <beng at jlab.org>
Sent: Friday, July 1, 2022 2:08 PM
To: Morgan Cook IV <mcookiv at jlab.org>; Marc Mcmullen <mcmullen at jlab.org>
Cc: dsg-hallb_dc at jlab.org <dsg-hallb_dc at jlab.org>
Subject: Re: DC CO2 mix 2?

Done.

https://logbooks.jlab.org/entry/4009546

Note that this change won't survive a power cycle of the controller.
________________________________
From: Morgan Cook IV <mcookiv at jlab.org>
Sent: Friday, July 1, 2022 1:57 PM
To: Brian Eng <beng at jlab.org>; Marc Mcmullen <mcmullen at jlab.org>
Subject: Re: DC CO2 mix 2?

Yeah, I think it's a pressure differential issue. It looks like the pressure differential between the CO2 tank and the mix 2 buffer tank isn't enough. For some reason the  CO2 tank isn't building pressure as it should.
Can you lower the fill mix 2 fill points from 80-100 psi to 70-90 psi?
________________________________
From: Brian Eng <beng at jlab.org>
Sent: Thursday, June 30, 2022 12:52 PM
To: Morgan Cook IV <mcookiv at jlab.org>; Marc Mcmullen <mcmullen at jlab.org>
Subject: Re: DC CO2 mix 2?

If I had to guess there was probably an issue with the zeroing. Best is if you can valve off both up and downstream of the MFC prior to zeroing, but at a minimum one of the sides needs to be valved off. Since I don't have the PI&D in front of me I don't know what's possible offhand.

These don't normally have such high flow when the valve is closed.

________________________________
From: Brian Eng <beng at jlab.org>
Sent: Thursday, June 30, 2022 12:39 PM
To: Morgan Cook IV <mcookiv at jlab.org>; Marc Mcmullen <mcmullen at jlab.org>
Subject: Re: DC CO2 mix 2?

Right now Mix 2 seems fine.

There seems to be issues with the mix 1 CO2 MFC. The valve is all the way closed but it still thinks there is ~6 l/min flow.

________________________________
From: Morgan Cook IV <mcookiv at jlab.org>
Sent: Thursday, June 30, 2022 12:15 PM
To: Brian Eng <beng at jlab.org>; Marc Mcmullen <mcmullen at jlab.org>
Subject: DC CO2 mix 2?

Hey Y'all,

When y'all get a minute, can you take a look at the DC mix 2 system? There is some new, strange behavior with the Mix 2 CO2 flow. It seems that when both Mix 1 and Mix 2 are calling for full flow, i.e filling the buffer tanks, there doesn't seem to be enough flow through the Mix 2 CO2 mfc.

This morning when I came in, the Mix 2 CO2 mfc was at 100% open with a zero/negative flow. They only way I got Mix2 CO2 to flow was to turn off Mix 1 completely, then Mix 2 seemed to work correctly. Reducing both the Mix 1 set pt and HTCC rotameter seemed to allow some CO2 to flow through Mix 2, but even then, then mfc creeps open to 100% to try and maintain the required flow.

The CO2 was filled a couple of days ago, and the tank and line pressure are a bit low but I can't quite figure out why only Mix 2 CO2 is affected. I did re-zero all the Mix mfcs but I don't think it changed anything.

Thanks,
Morgan

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://mailman.jlab.org/pipermail/dsg-hallb_dc/attachments/20220701/97cf1e8f/attachment-0001.html>