We have many older magnets still in service. Most have had the seals
replaced at one time or another following a new instrument purchase,
an upgrade or what have you. Two noteworthy exceptions:
An early Oxford 600, dual can, narrow bore - installed 1987: still up.
An Oxford 300 narrow bore - 1987: went soft in 2009.
cdr
On Jun 10, 2009, at 1:24 PM, Jane Strouse wrote:
>
>
> Dear AMMRLers,
>
> This is a really good question for a survey. Some of us have some
> seriously old magnets out there. We have several that are doing
> just fine,
> but I worry about this even in the face of no symptoms. I think it
> would be
> great if people with older magnets would provide some data. Here
> are the
> ages of our older (some ancient) systems (including two located in
> our space
> that belong to someone else):
>
> Oxford 300 MHz wide bore - installed 1988
> Oxford 500 MHz narrow bore - installed 1985 - dewar refurbished 1993
> Oxford 500 MHz narrow bore - installed 1986 - dewar refurbished 1993
> Bruker 500 MHz narrow bore - installed 1993
> Bruker 400 MHz narrow bore - installed 1994
>
> All of these systems appear to have no problems, i.e. hold time is
> the same,
> no increase in boil-off, etc. The two that were refurbished were
> relocated,
> so we took that opportunity to do it while there was a "moving"
> budget; they
> were not indicating any problems prior to the refurbishments.
>
> Jane
>
> Dr. Jane Strouse
> Director, UCLA Molecular Instrumentation Center
> (310)-825-9841 - voice
> (310)-825-2280 - fax
> strousej_at_chem.ucla.edu
> http://www.mic.ucla.edu
> Office: Room 1410 Molecular Sciences Building
> Mail: Box 951569
> Shipping: 607 Charles E. Young Dr. East
> Los Angeles, CA 90095-1569
>
>
> -----Original Message-----
> From: Zhang, Weixing [mailto:Weixing.Zhang_at_STJUDE.ORG]
> Sent: Tuesday, June 09, 2009 12:37 PM
> To: ammrl_at_ammrl.org
> Subject: AMMRL: When the magnet seal should be replaced?
>
>
> Hello everybody:
>
> We have two 600 MHz magnets and both of them are over 10 years old.
> I heard that the seal will age and need to be replaced at certain
> time.
>
> I would like to know:
> At what condition (e.g. He/N hold time, boil off rate) the seal must
> be
> replaced?
>
> What is the longest time that the seal can last?
>
> Thanks,
> Weixing Zhang
> St. Jude Children's Research Hospital
> 262 Danny Thomas Blvd
> Memphis, TN 38105
> (901)595-3169
>
>
> Email Disclaimer: www.stjude.org/emaildisclaimer
>
Christopher D. Rithner
Chemistry Department
Colorado State University
Fort Collins, CO 80526
970-491-6475 (ph)
970-491-0514 (fx)
970-980-8845 (cell)
email://cdr_at_colostate.edu
http://cif.colostate.edu
Received on Fri Jun 12 2009 - 10:29:31 MST