Dear All,
I just wonder... When we are talking about "long vt experiments very far
from rt" what does that mean?
I did contact Bruker in Switzerland about five years ago (they make the
probes, I guess) and asked for safe numbers regarding the vt temperature for
an elongated period of time ("hours to days"). I received the following
specs (for a new probe):
1. 5mm 500 to 750MHz TXI and QXI probes with XYZ-gradients: 223K to 353K
2. 5mm 500MHz TXI and QXI with z-gradients: 123K to 453K
3. 5mm 600 to 750MHz TXI and QXI with z-gradients: 123K to 423K.
BUT NOW COMES THE CATCH: The temperature of the shim-coil is at no time
supposed to exceed 353K !!! Here, the optional shim-system cooling accessory
comes into play.
In addition be aware that the O-rings of the magnet-dewar never must be
cooled below 263K! There also seem to be *heater* elements which can
optionally be mounted on the shim systems. A last warning about LOW
temperatures: Watch out for condensation (and ice-forming). A dry gas flow
can help to prevent this.
(Source: Andrew Cadman, Bruker CH, Jan 27, 2003)
Hope that helps one or the other out there...
Best wishes,
Rainer
***********************************************
Dr. Rainer Wechselberger
Supervisor EU-NMR Facility
Bijvoet Center for Biomolecular Research
Utrecht University
The Netherlands
www: www.lsf.chem.uu.nl
phone: 0031 (0)30 253 3295
fax: 0031(0)30 253 9254
************************************************
----- Original Message -----
From: "Jane Strouse" <strousej@chem.ucla.edu>
To: "BUM" <bruker-users-mail@purcell.cchem.berkeley.edu>
Sent: Thursday, May 22, 2008 9:49 PM
Subject: RE: vt shim cooling
> Dear All,
>
> As for Andrew Gibbs 2nd point, all Bruker customers who think they
> will ever do long vt experiments very far from room temperature should
> include this adaptor explicitly on their order and insist on having it
> at installation. It not only protects the magnet from a quench, but
> will alleviate the problem with shimming varying for a very long time
> after you are done with the vt experiment.
>
> Jane
>
> ----------------------------------------------------------------------
> Dr. Jane Strouse
> Director, UCLA Molecular Instrumentation Center
> 1410 Molecular Sciences Building
> Los Angeles, CA 90095-1569
> (310)-825-9841 - voice
> (310)-825-2280 - fax
> strousej@chem.ucla.edu
> http://www.mic.ucla.edu
> ----------------------------------------------------------------------
>
> -----Original Message-----
> From: Andrew Gibbs [mailto:andrew.gibbs@bruker.co.uk]
> Sent: Thursday, May 22, 2008 9:59 AM
> To: ligy; BUM
> Subject: RE: vt shim cooling
>
> Hi,
>
> I assume this question has already been answered, but I just thought I'd
>
> throw in my comments for good measure!
>
> 1) There is a temperature sensor in the shimset so if you have a concern
> you
> can check this value and take appropriate action! The example au
> program
> in the standard release is named 'coiltemp', which runs in the
> background
> and logs the temperature to a file. For extra safety you could also
> think
> to modify this program to take action if a temperature range is exceeded
>
> (for example of this try
> ftp://ftp.bruker.co.uk/pub/uknmr/auprogs/coiltempmon).
>
> 2) If you need one an adaptor is available for Bruker spectrometers that
>
> allows the connection of gas to flow over the shimset. You should
> contact
> your local Bruker office to get more details and a price!
>
> Best wishes,
>
> Andrew
>
> Dr Andrew Gibbs Phone (+44) 024 7685 5200
> Team Leader, NMR Applications Fax (+44) 024 7646 5317
> Bruker BioSpin Limited email: andrew.gibbs@bruker.co.uk
> Banner Lane
> Coventry
> CV4 9GH
> U.K.
>
> Registered in England and Wales with registration no 923986
> Registered office is Banner Lane Coventry CV4 9GH
>
>> -----Original Message-----
>> From: ligy [mailto:ligy@mail.sioc.ac.cn]
>> Sent: 16 May 2008 18:03
>> To: BUM
>> Subject: vt shim cooling
>>
>>
>> Dear all,
>>
>> Varian machines have a cooling system to protect the room
>> temperature shim
>> unit, which is very useful for a long vt experiment. I dont
>> notice such a
>> device on our Bruker av500. Is there a similiar cooling
>> system on Brukers
>> for vt experiments? And what is your solution in practice?
>>
>> Thank you in advance!
>>
>> Guangyu
>>
>> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>> Guangyu Li
>> Manager, Associate Professor
>> NMR Facility
>> Shanghai Institute of Organic Chemistry
>> Chinese Academy of Sciences
>> 354 Fenglin Lu
>> Shanghai 200032 China
>> Telephone: 86-21-54925012
>> Fax: 86-21-54925039
>>
>> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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