We've had this problem with the dewar on our 600 MHz Prodigy, Serial
Number-001 that was originally installed in 2012.
Besides elevated back pressure during the fill, there were also odd sounds
coming from the vent port.
I was able to clear the ice in the vent side by chipping and blowing warm
N2 gas with a flexible canula. It's been fine since then.
--Mike
-----------------------------
Michael Strain, PhD
Director, CAMCOR NMR Facility
University of Oregon
Eugene, OR 97403-1253
mstrain_at_uoregon.edu
541-346-4605 office/lab
541-556-4077 mobile
http://nmr.uoregon.edu
LinkedIn.com/in/michael-strain-3a8476119
On Thu, 15 Feb 2018, Karen Ann Smith wrote:
> Resonators;
>
> For the second time in less than 6 months, we have had to abandon the liquid
> nitrogen refill of the prodigy dewar. As happened last fall, the nitrogen
> gas out port is clogged or blocked. Nothing comes out, which means that the
> overpressure valve is triggered as soon as we try to put liquid nitrogen in.
>
> Last time this happened, Bruker said to:
> warm up the probe
> disconnect all hoses from the dewar
> dump out any remaining nitrogen
> warm up the dewar completely
>
> Then, re-connect all hoses, refill the dewar, and cool the probe. This
> results in over 24 hours of down time.
>
> I tried running a hose with nitrogen gas into the out port. It will go in
> about 6 inches before it hits something. I don't know if that is ice or a
> baffle.
>
> Does anyone have any suggestions that don't involve a day of down time?
>
> Does anyone have any suggestions of how to prevent this from happening? (My
> TA runs gas thru the fill line, unscrews the black caps, puts the vent hose
> on the out, runs a bit more nitrogen, then attaches the fill line.) The out
> line is only open for a few seconds.
>
> thanks,
>
> kas
>
> --
> Karen Ann Smith Director, NMR Facility
> Group Leader, Analytical Chemistry Services
> Department of Chemistry and Chemical Biology
> Clark Hall MSC03 2060
> 1 University of New Mexico Albuquerque, NM 87131-0001
> karenann_at_unm.edu 505.277.4031 http://nmr.unm.edu
> Out of this world screensaver: http://setiathome.ssl.berkeley.edu
> "Stress is what you get when your job is worthwhile and interesting"
> from "Encounter at Tiber" by Buzz Aldrin & John Barnes
>
Received on Tue Feb 20 2018 - 10:25:12 MST