About a week ago, I asked for advice on cooling VT air supplied to
NMR probes. Just a few hours ago, I posted a message containing a very
brief summary of the replies I received. Apparently, I underestimated the
level of interest in this subject. I have already received several
requests for more detailed information. Rather than responding to all
these requests individually, I am listing (see below) the text of all
suggestions I received. I hope this information proves useful to others
also.
Walt
Walter Tabaczynski
Cancer Research Scientist
Biophysics Department
Roswell Park Cancer Institute
Elm & Carlton Sts.
Buffalo, NY 14263-0001
e-mail: wt@labtwo.med.buffalo.edu
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>From dave@kunmr.chem.ukans.edu Wed May 8 10:18:08 1996
Walter, we use a 20 liter circulating chiller (a Lauda, but there are
several other manufacturers also) with 50 feet of immersed copper tubing;
we also circulate the chilled liquid around the tube leading to the probe,
all wrapped with insulation. This removes the need to replenish ice.
We get about as cold as you do without any other mechanism. However if
you hook up a small vacuum pump to a usually-unused port on the side of
the weird little diaphragm-containing object on the top of the magnet
with the other air hoses sticking out of it (presumably this widget has
some official and more compact name, but I don't know what it is),
and actively pump the air out of the probe, you can sustain substantially
higher airflows through the VT unit without displacing the sample, and
get several degrees colder that way. You do need to watch for vibration
problems, either from the pump, or with the way you are doing it, from
airflows not quite high enough to blow the sample out but enough to make
it chatter on the surface of the air bearing.
We recently went shopping for a DRX-400 (shipping at the end of
this week), and were quite impressed with the Bruker-engineered solution
with a semi-integral cooling bath in line all the time. It's quick-
responding and gets to ca. 0 C, no sweat. It is more expensive than
buying a bath direct and doing your own plumbing, but it clearly worked
better than our homemade setup. We were able to squeeze it into our
budget at the last minute during the bidding process. Cheers,
Dave Vander Velde, University of Kansas
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>From chesnics@fido.nhlbi.nih.gov Wed May 8 10:48:40 1996
Just a quick note on your VT problem. I would be careful on running house
"air " thru the probe for low temperature work. Water condensation can wreck
your capacitors and corode the coil.
I would just purchase a 250 Liters of liquid nitrogen in a stainless MR
dewar and run a insulated / regulated line from the dewar gas outlet to
the probe VT gas inlet. Try to keep the line short to avoid excessive warming.
A.Scott Chesnick
Electrical Engineer
IN-VIVO Nuclear Magnetic Resonance Center
NHLBI|LCE
NIH Bld10 Rm B1D-166
Bethesda,MD 20892
(301) 496 - 9441
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>From SILBER@chemvx.tamu.edu Wed May 8 11:06:58 1996
Walter-
I have used an airjet cooler from FTS for VT on biological systems
for a couple of years now with no particular problems. This is a refrigerated
system that cools the incoming gas to -40 or -80, depending on the model
you get, and then heats and regulates the temperature. This gives a very
stable gas temperature at the probe input, which I then regulate with the
instrument's temperature controller under computer control. I set the
airjet to 10-15 degrees below the desired temperature.
FTS Systems, Inc.
P.O. Box 158, Rt 209
Stone Ridge, NY 12484
(914)-6876-0071
The two models are XR401 (-40 degrees) and XRII851 (-80 degrees). The
851 was about $6000 in '94.
Hope this helps,
Steve Silber S-SILBER@TAMU.EDU or
Texas A&M University SILBER@CHEMVX.CHEM.TAMU.EDU
Department of Chemistry (409)-845-1745 (voice)
College Station, TX 77843-3255 (409)-845-4719 (fax)
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>From wu@csjindy.chem.unc.edu Wed May 8 11:11:09 1996
RFrom: wu@csjindy.chem.unc.edu (Donghui Wu)
Dear Walter,
I guess your first method is the most convenient way to do low temperature
experiments. If the ice bath is not enough, you might want to try dry ice,
or liquid nitrogen bath. Put more bends of copper tube into the bath will
also help.
Good luck!
Donghui
UNC-CH
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>From Jerry_Dallas@berlex.com Wed May 8 11:20:57 1996
Received: from ccgate.berlex.com(193.202.129.19) by fw.berlex.com via smap (V1.3)
Purchase a temp control unit from Bruker or from FTS. I
purchased a unit from FTS for my Varian spectrometer this
year. Before I could install it my older CryoCool unit (with
cold trap) failed on my Bruker AMX500. So we pressed the
FTS unit into service on the Bruker and it works quite well.
We plan to purchase a control unit from Bruker for the 500
later this year.
regards,
Jerry Dallas
Berlex Biosciences
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>From scott@zgi.com Wed May 8 11:45:56 1996
Hi Walter, at ZymoGenetics, we use a CryoCool refrigerated
cold finger made by Neslabs:
32970 Alvarado/Niles Rd
Union City, CA 94587
1-800-423-7831
Model # CC 65 II We didn't get the temperature control unit.
And we easily run at 275K. This is the same unit used by
Tom Pratum at the University of Washington. We stick the
cold finger into a bucket of isopropanol and run the NMR
cooling air through a metal tube immersed in this bath. It
works extremely well.
Good Luck,
Scott Harris
NMR Manager
---------------------------------------------------------
> <
> ====== ==== = SCOTT HARRIS <
> // = = = ZymoGenetics Inc. <
> // = = scott@zgi.com <
> // = == = scott@192.156.218.1 <
> ====== ===== = (206) 442-6772 <
> <
---------------------------------------------------------
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>From neil@u.arizona.edu Wed May 8 11:54:52 1996
From: "Neil E. Jacobsen" <neil@U.Arizona.EDU>
Walter,
The standard solution to this problem, I believe, is to buy a Haake
cooling bath. I think they cost around $2,000. The VT air supply is run
through a drier (this has to be more than just removal of liquid water - the
dew point has to come down lower than the Haake bath temp.) and into a heat
exchanger in the Haake bath before going to the probe. The Haake bath
should be filled with ethylene glycol / H2O (60% by weight) and run about
20oC lower than the regulated temperature at the probe. The bath will suck
up water from the atmosphere, so I just remove and dispose of the extra
volume when it starts to overflow, and measure the conc. of ethylene glycol
with a hygrometer (anti-freeze tester from any auto supply). A simple
calculation tells you how much volume to remove and replace with pure
ethylene glycol to get back to 60%. The air line from the Haake to the
probe has to be insulated. There is a special heat exchanger ("elephant's
trunk") available (from Bruker?) which runs from the Haake to the probe and
circulates the cooling bath fluid in this very thick hose as the air passes
through to the probe.
This seems to be the best system for biological (above 0 C) work.
Neil E. Jacobsen
NMR Facility Manager
Department of Chemistry
University of Arizona
Tucson, AZ 85704
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>From mayne@chemistry.chem.utah.edu Wed May 8 12:14:42 1996
From: mayne@chemistry.chem.utah.edu (Charles L. Mayne)
Walter,
If cost is not a major concern, check with FTS systems (800)824-0400.
If you're poor like me, dry ice/isopropanol or liquid nitrogen in your heat
exchanger will take you to lower temperatures. We have rigged up a device
to refill the heat exchanger with liquid nitrogen automatically from a
storage dewar. It is very much like the devices used to refill cryo traps
on mass specs. We run as low as -130 C for days at a time this way.
Charlie
Charles L. Mayne
University of Utah
Dept. of Chemistry
B103 HEB
Salt Lake City, UT 84112
Voice: (801)581-7413
FAX: (801)581-4763 or 8433
E-mail: mayne@chemistry.utah.edu
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>From Patrick_Wheeler@isisph.com Wed May 8 12:16:10 1996
From: "Patrick Wheeler" <Patrick_Wheeler@isisph.com>
Walter-
When we run very low temperature experiments, we run nitrogen gas (boil-off
from a dewar) through copper-coils in a bath of liquid nitrogen (if we need
VERY cold) or a bath of dry-ice/IPA.
Both methods are moderately clumsy, but give us pretty good stability.
-Pat W.
Patrick Wheeler
NMR Laboratory Manager
Isis Pharmaceuticals
2280 Faraday Ave.
Carlsbad, CA 92008
619-603-3801
pwheeler@isisph.com
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>From jbreeyea@moose.uvm.edu Wed May 8 12:17:11 1996
Organization: University of Vermont - Chemistry Dept
Had you considered a solid state refridgerator. I have never used
one.Peltier effect. I dont know any easy way to do it and insure that the
air is real dry other than the dry nitrogen thru some heat exchanger. We
do a lot of work down to 100kelvin but that takes some work to make sure
it is dry, dry, dry. I would think that dry ice in acetone would get you
plenty low with a mixer valve to regulate the warm nitrogen to keep the
temperature where you want it. Good luck. Jim.
--
-----------------------------------------------------------------------------
Jim Breeyear Manager, Analytical Instrument Lab
Chemistry Dept. Cook Sci. Bld.
University of Vermont
Burlington, Vt. 05405
Fax:802-656-8705 Voice: 802-656-0196 (also personal BBS)
-----------------------------------------------------------------------------
"No person is a failure who is enjoying life.....
William Feather (1888-?)
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>From charlie@telemann.pse.umass.edu Wed May 8 12:33:18 1996
From: charlie@telemann.pse.umass.edu (leonard charles dickinson)
we do a lot of vt on out amx2-500
we have used for 2.5 years the bruker chiller for incoming air to the
probe. it has been troublefree and extremely convenient. We do precondition
our air with a Balston air dryer (to -100degF dew point).
||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| |
|Dr. L.Charles Dickinson voice mail and office (413)5771428 |
|Director of NMR Instrumentation lab telephone (413)545-0630, -5413 |
|Conte National Center for Polymer Research fax (413)5450082 |
|Department of Polymer Science and Engineering office Conte Rm 428 |
|University of Massachusetts |
|Amherst MA 01003 USA charlie@telemann.pse.umass.edu |
| !!!!!!!!!!!!!!!!!!! |
| Only the shallow know themselves -Oscar WIlde | |
|>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>><<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<
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>From prasanna@tesla.mayo.EDU Wed May 8 13:01:07 1996
From: prasanna@tesla.mayo.EDU (Prasanna Mishra)
You may try FTS Crystal Cooler unit, which we are happily using.\
Their address is
FTS Systems
P.O.Box 158, Route 209
Stone Ridge
New York 12484
(914) 687-0071
------------------------------------------------------------------------
Prasanna K. Mishra mishra@mayo.edu
------------------------------------------------------------------------
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>From pratum@u.washington.edu Wed May 8 13:06:19 1996
From: "T. Pratum" <pratum@u.washington.edu>
One suggestion I have, which I am sure you will hear from others, is to
use a Neslab Cryocool immersed in something like isopropanol with a copper
cooling coil in it. This is a fairly maintenance free method to cover the
temperatures which are not too low, but lower than ice can attain.
Tom Pratum
Dept of Chemistry
Box 351700
Univ of Washington
pratum@u.washington.edu
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>From mjs@chem.ucla.edu Wed May 8 13:11:21 1996
From: Jane Strouse <mjs@chem.ucla.edu>
Dear Walter,
Neslab makes nice coolers for your type of application. I don't have
one so I can't recommend a model but I'm sure that lots of other people
could. I believe they are probably particularly good for days long runs.
We use a variety of solvents and conditions and seldom do a particular run
more than a day.
There are however cheaper alternatives to buying a Neslab cooler. One
that I like is to make a very skinny, deep heat exchanger coil that fits
into the the 25 liter dewar provided by Bruker for use with the N2 boiler
system you mentioned. The advantage of it is that you can run rather
reasonable flows for relatively high temperature and go an amazingly long
time without a refill. Additionally, I made mine with a plastic funnel down
the middle of the top so I can add liquid nitrogen at any time. (You can
also stick a skinny dowel down to the bottom through the funnel to check the
level.) I really like this system, but it's major drawback is that you must
use gaseous nitrogen rather than air during the run.
Another cheap alternative (at least for us because we have a good air
dryer with a fairly low dew point) is to use a dry ice/isopropanol bath. We
can use house air (after passage through our good dryer) and if you make the
bath fairly large you can go a pretty long time especially with the
relatively moderate flow rates needed for temperatures you would want with
water solutions.
Lots of luck.
Jane
Jane Strouse
Dept. of Chemistry & Biochemistry
UCLA
Los Angeles, CA 90095-1569
(310)-825-9841
(310)-825-0393 FAX
strousej@chem.ucla.edu
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>From fishbein@vax.grc.nia.nih.gov Wed May 8 14:28:27 1996
Walter,
Concerning your question on cooling VT air for solution NMR
experiments, we accomplish this task by passing dry compressed air from our
Balston desiccant drying unit through a copper heat exchanger coil immersed
in an ethanol circulating bath (Lauda MT-6). This arrangement should cover
the entire temperature range in which aqueous samples are studied. Bruker,
in fact, sells a cooling circulator called the "BCU-05" which permits
cooling to -5 C. However, buying a standard circulator from some
distributor like Fisher Scientific and building a simple heat exchanger
from copper tubing should give similar performance and save money, too.
Finally, note that Bruker sells the socket fitting to mate with the VTprobe
dewar (a "VT Heater/Transfer Dewar Coupling", Bruker part number 9151).
This socket can be attached to the end of a foam-insulated tygon tube, with
the other end attached to the output of the heat exchanger.
Regards,
Ken Fishbein
Facility Manager, NMR Unit
NIH/NIA/GRC
Ph. (410) 558-8512
FAX (410) 558-8173
E-mail: fishbein@vax.grc.nia.nih.gov
Address: Ken Fishbein
NIH/NIA/GRC
4940 Eastern Avenue
Baltimore, MD 21224 USA
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>From barry@sneezy.fhis.net Wed May 8 16:34:19 1996
Hi there!
We use a refrigerated circulating water bath filled with antifreeze
and set to it's lowest limit (so it runs continuously). This goes to
a cooler filled with antifreeze. Immersed in the cooler is copper tubing
much like your arrangement. Using this set-up, we have very stable
temperature control but can only get down to 5 C. This summer we will be
demoing an FTS cooling unit to see how it compares to our system.
Get back to me if you want more details. Good luck!
--
Barry Schweitzer, Ph.D.
Director Assistant Professor
Division of Structural Biology Department of Chemistry
Walt Disney Memorial Cancer Institute University of Central Florida
at Florida Hospital
12722 Research Parkway
Orlando, FL 32826
Phone: (407) 380-9977
FAX: (407) 380-9978
email: barry@sneezy.fhis.net
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>From BANGERTER%KEKULE@BIOMED.MED.YALE.EDU Wed May 8 17:50:40 1996
Walter,
Here in the Yale Chem. Dept. I use a Neslab immersion bath cooler (current
unit is the CC-65) to cool an isopropanol bath in a large cylindrical Pope
dewar. Immersed in the bath is a coil of copper tubing, about 4 turns at
4 in diameter. N2 is passed through the coil and then through a dewared
glass transfer line (built in our glass shop) to the Bruker probe. The
incoming N2 temp is about -20 deg C, and the system works well for samples down to -5 deg C or so. The system requires very little maintenance, except that
in time the bath will ice up and the isopropanol will have to be replaced.
We do this maintenance every couple of months, dependinmg on the humidity
and how well room air is excluded from the bath. Incidentally, I do not
use any controller for the cooling unit. I just have it running continuously,
and have had no problems in 4 years or so. Hope this is useful to you.
Regards,
Ben Bangerter
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>From pemberaj@sun1.bham.ac.uk Thu May 9 07:22:51 1996
Bruker now make a heat exchanger for long period probe
VT gas cooling. They used to supply a Haake bath with a
custom built heat exchanger with the early AMXs etc.
The system they supplied to us with our AMX500 works
very well in conjunction with the BVT2000 giving good
temperature control.
Tony P.
*******************************************************************
Mr. A.J.Pemberton
c/o Dept. Rheumatology, Tel: +121-414-3388/6795
Medical School, Fax: +121-414-6794
The University of Birmingham, Email: A.J.Pemberton@bham.ac.uk
Birmingham B15 2TT. www: http://iris.bham.ac.uk
U.K.
*******************************************************************
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>From rdw@interaccess.com Thu May 9 07:25:04 1996
Walter,
With convenience comes cost, but yes there is a much easier and
effective way of supplying controlled VT gas to your probe. We employ
an air "chiller" manufactured by FTS systems to control our N2 supply.
This machine runs constantly at -80C, and has a small heater at the
delivery end to control temperature. You simply set the desired temperature
on the control box and that's it!
The setup costs about $12,000.00.
If you need more info, write back.
Regards,
Rick Wintermute
Dexter Corp.
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>From kfw@lubrizol.com Thu May 9 09:59:52 1996
I have an FTS XR 401 air-jet cooler hooked to my AMX 500. This does a
nice job of precooling my nitrogen gas that goes to the probe. I leave
this on at all times with no problem of ice blockage. The system puts
out a constant -40C that is then controlled by a temperature unit that
brings the gas to a specified temperature (+/- 0.1C). The price of the
unit when I bought it was around $6,500.
If you have any further questions let me know.
Regards,
Kurt
--
##############################################################
Kurt Wollenberg e-mail:kfw@lubrizol.com
Research Chemist ph#:(216)943-1200 ext2026
NMR Spectroscopy fax:(216)943-9022
Lubrizol Corporation
##############################################################
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>From jimf@otsuka.com Thu May 9 10:06:51 1996
Subject: Re:
Try immersing the copper heaat exchange coil in a bath of Dri Ice
(CO2(s)) in isopropyl alcohol (not acetone!). This is cheaper than LN2
and not so much thermodynamic overkill.
--
Sincerely yours,
Jim Frye
email: jimf@otsuka.com
Otsuka Electronics USA Inc. phone: (970)484-0428
2607 Midpoint Dr. free phone: (800)4-OTSUKA
Ft. Collins, CO 80525 FAX: (970)484-0487
USA direct line: (970)484-1346 x244
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>From porubcan@peace.bms.com Thu May 9 10:42:58 1996
I used to attack this one with a cryo_cool as the cold source in your ice bath method 1) but found that the bath would
pickup condensate and freeze and..... well you;ve been there too.
A decent solution is to purchase an air-jet crystal cooler from FTS systems PO Box 158 Stone Ridge NY 12484 914)-687-0071,
I put one on a Varian UnityPlus 400 and it works great. Essentially your cooling air is precooled in a flexible delivery line (get the 15 ft option). NO BATH FLUIDS. Of course your 'air' must have a low dew point we use N2 gas from boiloff). You can us
e the controller to deliver precooled air to your probe. One unit precools to -40 and annother to -85. I have the -40 unit. I feed the precooled air to the standard varian probe VT inlet and do the final control with the Varian VT system. This way I
can precool to ~0C and ue the VT to control down to ~10C without the messy bath fluids. No worries about running
out of liquid N2 as in your method 2). Hope this works for you.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
------- Michael A. Porubcan Discovery Chemistry, NMR
/\ M / \ Bristol-Myers Squibb Pharmaceutical Research Institute
/ \ / \ PO Box 4000 Mail Stop E12-07
/ B \ / S \ Princeton, New Jersey 08543-4000
--------------
\ P / \ I / Fax: (609) 252-6601
\ / \ / Phone: (609) 252-4991
\/ R \ / Internet: Porubcan@peace.bms.com
-------
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>From Robert.A.Kleps@uic.edu Thu May 9 13:53:18 1996
I think NESLAB has some cold fingers or baths that might be useful near the
magnet. I have no personal experience with them.
Won't your water samples freeze, thaw and crack resulting in multitudinous
little fuzzy things to start growing at the bottom of your probe and users
saying words like, "You did what to my sample?"
Rob Kleps
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>From karenann@unm.edu Thu May 9 16:32:56 1996
Both Bruker and FTS sell air chillers. I don't know details about
Brukers, but FTS's is ~$5K + and will go down to -50C or so. Iowa State
has two FTSs - they just bought one a year ago. Dave Scott
(scott@iastate.edu) might have contact info.
Karen Ann Smith karenann@unm.edu
Manager, NMR Facility Adj. Asst. Prof.
Dept. of Chemistry Clark Hall
University of New Mexico Albuquerque, NM 87131
505.277.4031 url: http://www.unm.edu/~karenann
"Facts are the enemy of Truth" - Don Quixote
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>From tschudin@spider.niddk.nih.gov Fri May 10 10:50:17 1996
Walt:
We have about 7 Brukers, from 360 to 600, a 750 expected any day.
We use the following setup on all systems: House air passed thru
an air dryer (Balston, O'Keefe or any other brand). Air is then passed
thru a heat exchanger sitting in a dewar filled with methanol on the
way to the probe. In the dewar is the coldfinger of a Neslab immersion
cooler and a thermocouple. A homebuilt box that contains an Omega
temperature controller and a relay torns the cooler on about 10 min.
every hour and keeps the dewar at -20 C.
Let me know if you need more details
Cheers Rolf
|---------------------------------------------------------------|
|Rolf Tschudin Tel. 1 301 496 2692|
|Bldg.5, Rm.B2-29 _ Fax. 1 301 496 0825|
|National Institutes of Health _| |_ |
|Bethesda, MD 20892-0505 |_ _| E-mail: tschudin@nih.gov|
|USA |_| CompuServe: 71543,751|
|---------------------------------------------------------------|
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>From numare@cnj.digex.net Sat May 11 09:42:03 1996
Dear Walter
We've had success with a homebrew heat exchanger built out of 3/8" brass pipe
fittings and nipples. The heat exchanger is hooked into the air supply with
quick connect couplings and totally surrounded by pelletized dry ice. The
heat exchanger/dry ice assembly is contained in a cardboard box lined with
polyurethane foam panels. The tubing from the output of the heat exchanger
to the input of the probe air supply is jacketed with readily available foam
pipe insullation. The desired temperature is maintained by varying the air
flow from the VT unit. Very stable, 280 K no problem.
Can send a sketch if you are interested.
Best Regards,
Lawrence
--------------------------------------------------------
Numare Spectralab, Inc.,
10 Summit Avenue, Unit 6, P.O. Box 96,
Berkeley Heights, NJ, 07922-0096,
Telephone 908-665-0066
Telefax 908-464-4192
Name: Lawrence Byrnes
E-mail: numare@cnj.digex.net (Lawrence Byrnes)
www: http://www.cnj.digex.net/~numare/index.html
--------------------------------------------------------
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>From shelling@pop.uky.edu Sun May 12 18:19:08 1996
In the past, I have used a cryocool cooler with tubing attachments to the
probe. This was in Brian Sykes lab at the University of Alberta, some
years ago now when I was a graduate student. It worked well there but the
air is VERY DRY there so I don't know how it would work in a more humid
environment. If you like to get more info on this, contact Gerry McQuaid
at gam@polaris.biochem.ualberta.ca there at UA. I hope this helps.
Judith G. Shelling
PTRL East, Inc.
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>From AL_MARTON@chim.upb.ro Mon May 13 09:26:55 1996
From: "Anca Liana MARTON" <AL_MARTON@chim.upb.ro>
Organization: Department of Chemical Engineering
Dear sir,
I suggest you to use a bath of dry ice and acetone that is
producing up to 193 K. Hope this will be usefull.
George Marton
University "Politehnica" Bucharest
Romania
e-mail: al_marton@chim.upb.ro
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