Re: nmr tube ratings

Ross Mair (rmair@stan.xx.swin.OZ.AU)
Fri, 17 Dec 1993 23:14:50 +1100 (EDT)

Robert Scott wrote:
>
> Thanks to everyone for your tube comments. This has taken me longer to
> digest than Thanksgiving dinner but I've learned a lot.......
>
> and 20% feeling that hot or long drying in ovens are the root of all
> warped tube and insert problems. Wilmad recommends drying on a
> perfectly flat tray at 125 deg C for 30 to 45 minutes,,,,,it may get
> out of round and not fit in the spinner but not bent and ruin the probe.
>
> Wilmad:
> 528's ordered over a period of 4 years scoring inserts,
> only one spot on the tube showed wear.
> 507's for everyday,,, 528's for important
> Thrift tubes work well 99% of the time with no scoring observed.

We have had serious problems with thrift tubes not spinning in the magnet.
(Gemini 200) This we believe is due to non-perfect roundness. Some have
grated on the probe and the probe subsequently leaving marks on the tube.

They are dried
in an oven standing up, but so are our 507's, and we never have a problem
with them. We have tossed probably 10-15 thrift tubes which eventually
resisted all attempts to spin inside the magnet (despite slipping thru the
spinner with no problem whatever).

Ross

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Ross Mair Email: rmair@stan.xx.swin.oz.au
NMR Lab Snail: Mail 41, Swinburne University,
Applied Chemistry Dept PO Box 218, Hawthorn, 3122.
Swinburne University of Technology Fax: +61-3-8190834
Hawthorn, Victoria, Australia Voice: +61-3-8198843
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