[Dsg-rich] New alarms for RICH N2 main and backup supply pressure

[George Jacobs]

Another option would be to decrease the back up gas flow rate in order to increase the time each N2 bank lasts.

I would still recommend having 2 additional N2 banks on hand due to the  2 week lead time for this item. There is some overhead on utilizing these spare N2 banks. The empty banks would need to be removed from the hall to make space for the replacements. This involves the Hall B overhead crane, a flat bed truck, and a fork lift, along with the operator and a 2nd person, in order to change out an N2 bank.

We should also determine at what pressure should an N2 bank be replaced? If it's only 1/2 full, it will only last 15 hrs, not 30 hours.

An additional recommendation would be to use an alternate N2 supply, such as a dewar, for any planned N2 supply outage. That way the backup gas will be available for an unplanned outage.

George


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George Jacobs
Jefferson Lab (TJNAF)
STE 12
12000 Jefferson Ave.
Newport News, VA 23606
(office) 757-269-7021
(email) jacobsg at jlab.org


________________________________
From: Dsg-rich <dsg-rich-bounces at jlab.org> on behalf of Amrit Yegneswaran
Sent: Wednesday, June 12, 2019 6:01 PM
To: Tyler Lemon; dsg-rich
Subject: Re: [Dsg-rich] New alarms for RICH N2 main and backup supply pressure

thanks for the explanation.
from your graph it appears that once the pressure drops to 10 psi the nitrogen lasts for about 30 hrs,
question is this adequate time for re-establishing main nitrogen flow.

perhaps, we should keep spare banks (24 cylinders) available.
any ideas?
amrit

________________________________
From: Dsg-rich <dsg-rich-bounces at jlab.org> on behalf of Tyler Lemon
Sent: Wednesday, June 12, 2019 3:47 PM
To: dsg-rich
Subject: [Dsg-rich] New alarms for RICH N2 main and backup supply pressure

Hello,

After last week's issue of losing N2 flow to RICH, we have implemented two new alarms for the status of the RICH N2 supply.

The first alarm is on the main N2 supply pressure. It is set to alert Hall B Engineering if the main N2 supply pressure at the RICH panel drops below 20 psi for more than 60 seconds. This will indicate that the main N2 supply has been lost and the backup system has started to provide nitrogen to RICH. Using data from last week's nitrogen stoppage (attached) as an example, this alarm would have tripped at one minute after the main flow supply valve was closed.

The second alarm is on the backup N2 supply pressure. It is set to alert Hall B Engineering if the backup N2 supply pressure drops below 10 psi for 60 seconds. This will indicate that the backup N2 supply has started to run out. This alarm would have tripped last week as the backup supply started to run out.

Looking at data for the backup N2 supply pressure, we will also look into adding another alarm at ~15 psi. This alarm would indicate that the backup supply has switched to the second nitrogen bank of the backup system.

With these new alarms, we will be notified of any significant change in RICH N2 supply and be able to take action before N2 flow drops to 0 slm.

Best regards,
Tyler
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