[Esr-users] [New Logentry] Hall B Cryo event

[David Kashy]

Sandesh and Hall B team,
Nice summary of this event
Let’s keep an eye for it repeating or getting worse
Thanks
Dave

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From: Esr-users <esr-users-bounces at jlab.org> on behalf of gopinath--- via Esr-users <esr-users at jlab.org>
Sent: Friday, April 12, 2024 3:15 PM
To: esr-users at jlab.org <esr-users at jlab.org>; hallb-engineering at jlab.org <hallb-engineering at jlab.org>
Subject: [Esr-users] [New Logentry] Hall B Cryo event

Hall B Cryo event<https://logbooks.jlab.org/entry/4278785>

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Lognumber 4278785<https://logbooks.jlab.org/entry/4278785>. Submitted by gopinath<https://logbooks.jlab.org/user/gopinath> on Fri, 04/12/2024 - 14:50<https://logbooks.jlab.org/entries?start_date=1712944237&end_date=1712951437&book=HBLOG&book=HBTORUS&book=CLOG>.

Logbooks:       HBLOG<https://logbooks.jlab.org/book/hblog> HBTORUS<https://logbooks.jlab.org/book/hbtorus> CLOG<https://logbooks.jlab.org/book/clog>
Entry Makers:   gopinath, tucker, mealer, docherty

Hall B buffer Dewar saw a pressure spike of 0.12 atm at 9:21 am which the system recovered from in the next 10 mins without any issues.

Investigation began in to finding the reason for this spike through the afternoon. Cryo (Brendan) was contacted to see if they had seen any anomalies on the ESR side - none was reported. He mentioned changes in the Torus LHe reservoir level leading up to the pressure spike.

Upon further investigation under Dave Kashy's guidance, we found that the LHE level (LL8120SC) in the Torus dewar dropped below the setpoint around 9:12 am (87%), causing the valve (EV8115JT) to open and increase level to 94% by 9:20 am. At this point the valve throttled the flow which saw a rapid drop in the 4.5K flow (CFI6711B) to the hall from 7.52 g/s to 5.16 g/s in 50 seconds. This caused the pressure (PT8512) to build up 4.5K supply line to Hall B and also was seen in the Buffer dewar (PI8210).

Similar rate and limits of valve actuation and the increase in the LHe level have been seen before BUT did not cause the drastic change in flow rate and pressure spikes. Further investigations are being conducted which includes checking solenoid & buffer dewar condition during this spike. We will continue to monitor these signal over the weekend.

[https://logbooks.jlab.org/files/styles/plentybig/public/2024/04/4278785/clonpc19_20240412_144021.gif]
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