[Dsg-rich] decrease Nitrogen flow to see how RICH humidity is affected

[Tyler Lemon]

Hello Marco Contalbrigo, 

On slide 6 Marco Mirazita's presentation, there is data showing the internal humidity of RICH can be maintained below 5% with only 15 L/min of nitrogen flow. 

In ideal conditions , single dewar can provide ~160,000 L of nitrogen. Since, we will be using four dewars in parallel over the shutdown, the amount of nitrogen we have is 640,000 L. If flowing at 35 L/min, four dewars will last about 14 days. If flowing at 15 L/min, four dewars will last 28 days. 

We know that the dewars we get do not have perfect insulation and that we cannot guarantee ideal conditions because we seem to get dewars that are only half full when we use them. Even with a margin of error for badly insulated and half-full dewars, flowing at 15 L/min could provide enough nitrogen flow to ensure humidity does not increase over the 10 days no one is at JLab. 

If the flow is not decreased and left at ~35 L/min as it has for the past week, we are only increasing the chances that we will run out of nitrogen over the shutdown. 

Best regards, 
Tyler 


From: "Mirazita Marco" <Marco.Mirazita at lnf.infn.it> 
To: "Tyler Lemon" <tlemon at jlab.org> 
Cc: "dsg-rich" <dsg-rich at jlab.org> 
Sent: Friday, December 22, 2017 4:40:49 AM 
Subject: Re: [Dsg-rich] decrease Nitrogen flow to see how RICH humidity is affected 

Hi all, 
these studies have already been done, see my presentation at the DSG 
meeting on December 6: 
https://clasweb.jlab.org/wiki/images/0/04/RichReport_DSGmeeting-2017-12-06.pdf 
Marco 



Il 2017-12-21 19:05 Tyler Lemon ha scritto: 
> Hello Marco Contalbrigo, 
> 
> Today, it would be good to do a test overnight to see how RICH's 
> internal humidity is maintained if its nitrogen flow is decreased. 
> 
> RICH is now in a steady state with its internal humidity at or below 
> ~3%. We could lower the nitrogen flow from ~35 L/min to ~25 L/min to 
> see how, if at all, the internal humidity changes overnight. 
> 
> If we are able to maintain an acceptable humidity with a lower flow, 
> it would lessen the chances that we will run out of nitrogen over the 
> shutdown. 
> 
> Best regards, 
> 
> Tyler 
> 
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