[Dsg-ltcc] leak rate

[David Anderson]

I do not recall exact numbers however, any drop that couldn't be accounted for due to barometric pressure changes 
(Thanks to Steve Cristo' Math) were considered leaks and I started over sniffing/fixing leaks until I was satisfied all pressure changes could be accounted for.
Sorry I cannot be of more help than that....

David

----- Original Message -----
From: "Amrit Yegneswaran" <yeg at jlab.org>
To: "David Anderson" <dla at jlab.org>, "dsg-ltcc" <dsg-ltcc at jlab.org>, "Douglas Tilles" <tilles at jlab.org>, "Maurizio Ungaro" <ungaro at jlab.org>
Cc: "Patrizia Rossi" <rossi at jlab.org>
Sent: Tuesday, April 18, 2017 8:50:34 AM
Subject: Re: [Dsg-ltcc] leak rate

hi dave, 
thanks for the info. 
this is good news. 
do you remember what the pressure dropped to after 3 days (from 2 in H2O). 

hi brian, george, and marc. 
given this information by dave, and what marc showed me, i'm not convinced that the epics archiver is working properly. 
we should investigate this issue (cRIO side as well as the epics side) and come up with a leakage rate for each sector. 
amrit 


From: "David Anderson" <dla at jlab.org> 
To: "Maurizio Ungaro" <ungaro at jlab.org> 
Cc: "Amrit Yegneswaran" <yeg at jlab.org>, "dsg-ltcc" <dsg-ltcc at jlab.org>, "Patrizia Rossi" <rossi at jlab.org>, "Douglas Tilles" <tilles at jlab.org> 
Sent: Tuesday, April 18, 2017 7:07:08 AM 
Subject: Re: [Dsg-ltcc] leak rate 

The procedure was as Mauri stated, that was the procedure that was decided upon. 

However, to be thorough leak checking, each box was injected with R134a and leak checked over the course of a week. 
Once no more leaks were found the boxes was left pressurized @ 2" WC and monitored for a minimum of 3 days, barometric pressure was taken into account for pressure changes. 
This procedure was repeated in the hall before installation and if needed once again when installed. 
After isolating the chambers from the gas system (After installing) only 2 leaks were found in the boxes and repairs were made as needed. 
No more leaks were evident..... 

Thanks, 
David 

----- Original Message ----- 
From: "Maurizio Ungaro" <ungaro at jlab.org> 
To: "Amrit Yegneswaran" <yeg at jlab.org> 
Cc: "dsg-ltcc" <dsg-ltcc at jlab.org>, "Patrizia Rossi" <rossi at jlab.org>, "David Anderson" <dla at jlab.org> 
Sent: Friday, April 14, 2017 2:33:25 PM 
Subject: Re: [Dsg-ltcc] leak rate 

Hi Amrit, 

The boxes were leak tested in two ways: 

1. sniffing freon from around the box - fixing all detectable leaks 
2. filling the boxes with nitrogen and checking that, taking atmospheric pressure into account, the box hold the pressure 

We didn't quantify the leaks. 

David, who is cc-end and did this work, can provide further details. He did it three times: 

1. as preparation, in TED. 
2. once the boxes were in the hall 
3. once the boxes were mounted on the forward carriage. 

He found considerable leaks in both 1 and 3 cases. 

Regarding your question on the LTCC window. 
That was 3mils or mylar = 0.0762mm, which has radiation length of 285 mm. 
So radiation length X/X0 = 0.0267%. 

It was sandwiched betwen 1.5 mils of tedlar, I think it has similar rad length. 

Regards, 
Mauri 







> On Apr 14, 2017, at 11:53 AM, Amrit Yegneswaran <yeg at jlab.org> wrote: 
> 
> hello, 
> 
> i see from my records that the ltcc leak test was performed jul/aug of 2015. 
> i do not have records of what the leak rate was at that time. 
> all i have e-mails saying that the leak test was successful and that the ltcc were taken to the hall before the final seal was done. 
> 
> i'm sure that someone has a record of the leaks, for each sector, that were measured at that time. 
> i would like to compare the present leak rate with that measured at that time. 
> 
> thank you for your help. 
> sincerely 
> amrit 
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