[Dsg-rich] [Rich] rich air flow

Sun Oct 14 10:28:51 EDT 2018

Hi Valery, 

I agree, the plot looks normal after 18:40 on October 13. 

Attached is the same plot you shared, but with annotations showing the pressure measurement any time the value looked to be under 40 psi. The lowest it seems to have gotten was ~36 psi. 

Also, the archiver doesn't ever show that the hardware interlock for the air pressure ever tripped. It's low limit is set to 35 psi. 

Best regards, 
Tyler 

From: "Valery Kubarovsky" <vpk at jlab.org> 
To: "Tyler Lemon" <tlemon at jlab.org> 
Cc: "Mirazita Marco" <Marco.Mirazita at lnf.infn.it>, rich at jlab.org, "dsg-rich" <dsg-rich at jlab.org> 
Sent: Sunday, October 14, 2018 10:15:03 AM 
Subject: Re: [Rich] [Dsg-rich] rich air flow 

Hi All, 
I got several calls yesterday evening and today night from CLAS12 shift about AIRPR1 alarm (currently minimum set to 35). See attached plot. I changed this limit to 30 for a moment. The plot looks not normal before Oct.13 18:40 in my view. 
Regards, 
Valery 

From: "Tyler Lemon" <tlemon at jlab.org> 
To: "Marco Mirazita" <Marco.Mirazita at lnf.infn.it> 
Cc: rich at jlab.org, "dsg-rich" <dsg-rich at jlab.org> 
Sent: Friday, October 12, 2018 9:25:18 AM 
Subject: Re: [Rich] [Dsg-rich] rich air flow 

BQ_BEGIN

Hello, 

Enough time has passed since I reset the cRIO's averaging to be able to tell that the averaging is not the cause of the odd airflow and pressure signals. 

Attached are archiver plots, one from today, and one from July when averaging had to be reset. 

The one from July shows the signal returning to normal soon after resetting the averaging. The signal from today does not show the same behavior. 

It seems the most likely cause is the drop in ambient pressure. 

Best regards, 
Tyler 

From: "Tyler Lemon" <tlemon at jlab.org> 
To: "Mirazita Marco" <Marco.Mirazita at lnf.infn.it> 
Cc: rich at jlab.org, "dsg-rich" <dsg-rich at jlab.org> 
Sent: Friday, October 12, 2018 8:16:43 AM 
Subject: Re: [Rich] [Dsg-rich] rich air flow 

Hello Marco and Valery, 

>From the past behavior of the cooling system, we know that the airflows follow the pressure in the cooling system's buffer tank. The attached "RICH airflows and pressure 2018-10-12.JPG" shows this. 

It also looks like the buffer tank's pressure follows the ambient pressure in the hall (attached RICH pressure and Ambient pressure.JPG; NOTE units for the two pressures are not the same. RICH's is in psi, the ambient is in inches-water-column). This could be the cause of the ~10 slm decrease in airflow. 

Also, in the past, we have seen issues where the signal averaging in the interlock LabVIEW program needs to be reset. To make sure this wasn't the cause of the odd flow and pressure readings, I reset the averaging on the LabVIEW User Interface at about 8:06AM. If it turns out the averaging was the cause of the odd signals, we will either disable the averaging until a solution is found or put in logic that will automatically reset the averaging every week or so. 

To make sure that there isn't some other issue with the compressor, we will look into a way to remotely access the status of the compressor in case we are missing some sort of warning on it that would explain the behavior. This most likely be setting up the compressor's web interface. Setting up the web interface has not been done yet because collaborators expressed concern about putting an accessible way for someone to accidentally turn the compressor off. 

In the mean time, we will continue monitoring. 

Best regards, 
Tyler 

From: "Mirazita Marco" <Marco.Mirazita at lnf.infn.it> 
To: "dsg-rich" <dsg-rich at jlab.org>, rich at jlab.org 
Sent: Friday, October 12, 2018 4:32:35 AM 
Subject: [Dsg-rich] rich air flow 

Hi all, 
I noticed that in the last couple of days the air flow on the two lines 
feeding the RICH went down by approximately 10%. 
At the same time, the FPGA temperatures slightly increased. 
Then at some time tonight the air flow started to go up again. 
While no real problem has been encountered (tile 128 is the hottest one 
and never went above 68 deg) it would be interesting to understand why 
this happened. 
See the attached strip charts. 
Best regards, 
Marco 

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BQ_END

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