Dear All
I could not help but smile at the timing of Ruth's summary of 'how
to euthanize a magnet'. Me and my colleagues had the Dr.Kevorkian
moment today when we euthanized our long suffering 750 MHz magnet. It's
all perhaps routine in our universe that does not warrant dragging your
attention with another post, but when I saw Ruth's summary, I thought I
indeed can add a small piece to the existing corpus on killing NMR
magnets, which most probably has not been recorded thus far.
Yes, there were no potential 're-users' of my magnet once
decommissioned and it will only be surplussed. Added to this, we did not
possess the original charging rods/cables nor the actuator unit that can
open the valve at the bottom plate of the magnet, which will be used to
break the vacuum. So, we simply opted the 'drill baby, drill' approach.
Got hold of a long enough stainless steel drill bit attached to a
cordless drill (with the usual short drill bit, when you go close to the
magnet body, the motor simply stalls), stuck a piece of wood on the side
of the magnet and drilled. It took a while but sure enough we could hear
the 'whooosh' of air rushing into the vacuum space, eventually. I had
earlier removed the one way valve at the Helium vent port in the
manifold and stuck a ball of paper towel. After the vacuum break, it
took couple of minutes before the paper ball was ejected out by a large
plume of vapor. I had about 50% Helium above 0 mark and the LN2 pretty
much run dry, when we started. About five more minutes later the quench
came. The white vapor filled the rather large lab space and it was as
if the ceiling has come down to about 8 feet height. The air handler
did an impressive job of clearing the entire place of the vapour in
about ten minutes. Effectively about 600 L of liquid Helium had been
vented out.
Good bye 750. We will miss you...
Rajan
p.s.: We are getting a shiny new 800 to replace this one by fall 2011.
Yes, with a cryoprobe (crossed x fingers).
*_______________________________
Rajan K Paranji, Ph.D.
*NMR Facility Manager
Department of Chemistry
Room 65, Bagley Hall
University of Washington
*Seattle, WA 98195*
*ph: 206 685 2581 pager:206 680 3779
fax: 206 685 8665
email: paranji_at_chem.washington.edu
___________________________________*
Received on Wed Jul 27 2011 - 15:05:28 MST