[Esr-users] [Revised Logentry] Follow-up Re: Follow-up Re: Follow-up Re: Torus Burp November 2020

[kashy at jlab.org]

Logentry Text:
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Burp was quite severe! 
TC8103 hit 0.131Torr, Peak from May 2019 was 0.05 torr
We should not wait this long again between burps.

07:30 Started get a spare pump ready to help in case the vacuum got bad in the Torus, hunting fittings, hoses, transducers etc.
08:02 LN2 Reservoir in the Torus started to empty
8:53 The lower Turbo pump isolation valve closed. 
9:38 Calvin and I put a spare blower in parallel with the hard piped blower. This second pump is not ideally plumbed because we do not have all the proper fittings to get maximum throughput (ie 4 inch line all the way). 
Adding the additional pump did reverse the pressure rise and start it falling.

09:45 We increased the maximum position of the LN2 Supply valve to the Torus from 60 to 90% to try to get the shields to cool

10:47 The pressure got so bad that the LN2 thermosiphon cooled heat shields got vapor locked but it is starting to clear. 

11:42 Liquid is now collecting in the LN2 reservoir

11:45 Recovery from this second burp is taking much longer than the last time mostly because the lower pump is isolated and of course amouont of time between burps was longer. 

Suggested improvements are:
1) Get larger backing pumps for the turbo pumps, this should help in reducing the load on the Turbos when the vacuum spoils (intentional burp or non intentional such as an ESR outage)
2) Get a full second blower system with proper tubing for easy connection (with an outlet that allows connection to emergency power)

The lower pump isolation valve is setup to open when the magnet pressure (TC8102) gets down mid E-3 torr. At present ti is 5E-2 torr and slowly falling

~13:00 manually put the lower turbo back on line by turning it off and letting the speed coast down to 180Hz the forcing the gate valve open then starting the turbo and putting the gate valve back in auto
~13:30 lost the IOC for the DBX, Attempted a hard reboot, no luck, Called in Nic Sandoval
Relief valve on Solenoid lead reservoir lifted 

Called Cryo and asked that 4K supply and Return valves be closed. Chris Perry took care of this

Put PV8522SCD in Manual mode at 100% and also PV8522SR in manual mode at 100% to give vent paths for both the Solenoid and the Buffer dewar to return their boil off.
Solenoid seems to be empty but Buffer dewar has ~250 liters in it. 
2:25 Correction the Solenid acualy is 90% full the SC level sensor was not reading properly because the magnet pressure was too high. now that it is back down to 1.3 atm it reads. Readers of this entry are welcome to try to explain this phenomenon :) Just send me an e-mail (kashy at jlab.org) 






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