Hi Neil, Roger and All
Once in a few years, we pull out the RT shim stack and and clean up
the top flange with Iso-propanol, where the tiny turbine holes are
located. We do notice surprising bit of gunk collecting over years and
normally the tell tale sign is the spinning of sample becoming erratic,
even after you do a spin calibration, after a few days. I too use the
technique of increasing eject air flow at first and recently Bruker
suggested that you can jack up the VT air flow to a large value to help
in this process.
Best wishes
Rajan
On 09/01/2012 07:52 PM, Kautz, Roger wrote:
>
> ----- Original Message -----
> From: Jacobsen, Neil E - (neil) [mailto:neil_at_email.arizona.edu]
> Sent: Friday, August 31, 2012 06:32 PM
> To: ammrl_at_ammrl.org <ammrl_at_ammrl.org>
> Subject: AMMRL: Samples ejecting (like missiles) from magnet
>
> I have a similar problem with our DRX-500. The Oxford magnet is more than 20 years old but the shim stack and bore tube are circa 1999 (DRX). On very rare occasions the sample gets stuck in the magnet and will not eject. Sometimes you can turn up the air pressure a lot and get it to suddenly release and launch into the air. Other times nothing works and we have to push the sample up from below (after removing the probe) with a wooden stick. I find it hard to believe that just finger goo or dirt could cause that, but I swab out the probe with ethanol afterwards just in case. There is nothing unusual about the sample tube. Maybe someone can tell me what causes this!
>
> Neil
>
> Neil E. Jacobsen, Ph.D.
> NMR Facility Manager
> Department of Chemistry and Biochemistry
> University of Arizona
> 1306 E University Blvd.
> Tucson, AZ 85721
> 520-621-8146
>
> ________________________________________
> From: transplatin_at_gmail.com [transplatin_at_gmail.com] on behalf of Ken Knott [kknott_at_vt.edu]
> Sent: Friday, August 31, 2012 7:52 AM
> To: ammrl_at_ammrl.org
> Subject: AMMRL: Samples ejecting (like missiles) from magnet
>
> Hello everyone..
>
> In our Agilent MR400 system we have an occasional but increasing
> issue. Every once in a while, sometimes once a week, sometimes twice
> in a day, samples will literally fly out of the bore to crash on the
> magnet and eventually shatter on the floor.
>
> Nothing has changed in the gas regulators in the console nor the air
> regulators feeding the console. They are all set as they have always
> been.
>
> It seems as if something is getting stuck, pressure builds, and
> releases suddenly upon eject...
>
> Has anyone come across an issue like this?
>
> Thanks,
>
> Ken Knott
>
> Assistant NMR facility manager
>
> Virginia Tech
>
> 540-231-8256
>
--
____________________________________
____________________________________
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
fax: 206 685 8665
email:paranji_at_chem.washington.edu <mailto:paranji_at_chem.washington.edu>
____________________________________
Received on Thu Sep 13 2012 - 08:22:40 MST