Dear All,
Thank you so much for the many replies. I realize now there’s more information needed. We’re looking at a large 9.4 T wide bore horizontal MS magnet. Approximately 700L of He full, and ~490L at the expected quench point (horizontal is a different beast).
The magnet is not to be used again (i.e. decommissioned completely), but we can’t simply let things boil off and quench randomly. Why you would logically ask? We’re in a sub-basement without purge vents of any kind and the floor is occupied by many labs in an open environment (i.e. dividing walls only go up ~90% to the ceiling). So we need to know when it’s going to quench (it actually has a quench system installed). How it was installed in this fashion escapes me and was far before my time.
We’re working on a duct to vent the gasses to a service elevator shaft that opens to the outside, and planning for an early weekend morning with ample warning to the occupants and support services.
The quotes for outside experts to come in, bringing a power stick and decommission by de-energizing has been in the $13+k ranges which the group likely can’t afford. Especially since there’s no guarantee it’ll go gently even if that method is chosen.
We may end up paying the fee, we’re just looking at options.
Again many thanks to all the fantastic people who have sent in their suggestions, ideas, and experiences. I’ll try to write up a formal document and post it here just in case it’s of use to anyone else.
All the best as always,
Ryan
Dear All,
Does anyone have an SOP for force quenching a magnet? Yes I can’t believe I’m asking that ….
We’re looking at a decommissioning procedure for a magnet where either the control/power stick is not available or the pins at the bottom are damaged (i.e. can’t tap in to control the de-energization).
Wondering if anyone has written up and summarized items needing to be checked before and during the event?
e.g.
contact fire and security
arrange for emergency fans to be running or set up portable fans to move helium outside
schedule a time away from normal hours (e.g. weekend evening)
warn the department/workers well in advance and provide hazard information
signs in all corridors warning people away
other things?
etc.
Items I’d really appreciate experience on:
Full or minimal helium content?
-is it safer to let helium run so low it quenches (uncontrolled time) or spoil the vacuum and pull out cryogens (controlled)?
Full or empty N2?
The situation is to decommission and dispose of the magnet, so safely quenching for later use is not an issue.
I’d greatly appreciate your experience, advice and suggestions,
Ryan
-----------------------------------------------------------------------------------
Ryan T. McKay, Ph.D.
NMR Laboratory Supervisor
Room E3-17A Email: ryan.mckay_at_ualberta.ca <mailto:ryan_at_nanuc.ca>
Department of Chemistry Phone: (780) 492-9950
University of Alberta Fax: (780) 492-8231
Edmonton, Alberta Cell: (780) 920-8871
Canada T6G 2G2
http://www.chemistry.ualberta.ca <
http://www.chemistry.ualberta.ca/>
Received on Tue Aug 11 2015 - 10:35:41 MST