Date: Mon, 14 Jun 2010 14:41:50 -0400
Thanks so much to Joseph Asta, Beverly Ostrowski, Martha Morton, Youlin Xia,
Sean Moran, Dee-Hua Huang, Gary Martin, W. Dale Treleaven, Sean Cahill, and
Jerry Hirschinger for the prompt response to my post:
"The NMR lab at Princeton University is looking for chillers for
water-cooled compressors for cryoprobes."
The complete collection of responses can be found below. They point mainly
to one manufacturer that seems to provide reliable product(s), flexibility
of design, and good service support. It was highlighted that great caution
should be used on the decision of running the heat exchanger with
closed-loop chilled water or an in-house chilled water. In one lab the
cryo-compressor is cooled directly with tap water, then waste to drain.
Finally, one a sideline topic, it was discussed whether it is operationally
a good plan to chill more than one cryo-compressor with a single chiller:
the response was mostly that, albeit more expensive, it is safer to use one
chiller per cryo-compressor.
Once more, our sincere thanks to all and to the always useful forum provided
by AMMRL.
With Best Regards,
Carlos
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Carlos Pacheco, Ph.D.
Sr. NMR Spectroscopist/CW-EPR Manager
Princeton University/Chemistry - Frick Lab, Washington Road
Princeton, NJ 08544-1009
Phone: (609) 258-1633; Fax: (609) 258-6746;
E-mail: cpacheco_at_Princeton.edu; Webpage: http://www.princeton.edu/~nmr
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
************** SUMMARY **************
1) I recently purchased one from Haskris (www.haskris.com). It has a heat
exchanger that sits outside, and a unit inside that pumps the cooling water
from the unit to the cold probe. I designed a custom controller that
monitors the cooling water temperature and pump flow rates, and will switch
over to city water if there is a failure. It also has switches that control
the water solenoid valves, so you don't have to open & close valves
manually. Haskris did an outstanding job working with me on this custom
design.
. The unit we purchased is for two cold probes (model R550); it uses 208
3-phase. Both the inside and outside units are quite large, I have the
dimensions if you are interested. One chiller was more cost effective than
purchasing separate units for each cold probe.
Haskris gives a choice of power - either single or three-phase - for the
unit designed to chill one cold probe (model R300). I do not have the
dimensions for it.
Doug Wagner (847-956-6420 ex 243) at Haskris was very helpful, and I am sure
he could answer any questions you may have.
Do you have the cold probes already? Both brand "B" and "V" now offer an air
cooled compressor unit. It would be nice to not have to use cooling water. I
tried to avoid using cooling water, but it wouldn't work for me. The NMRs
are in the basement, and too far from an exterior wall. I believe all cold
probes require 208 three phase.
2) We have two Haskris models on each cryoprobe/cold probe:
http://www.haskris.com/Cooler_Product_Lines.aspx;
http://www.haskris.com/Documents/Haskris_DualPress.pdf.
My advice on these - use really pure water for the bath - we use potable
water. Make sure you check the bath so in case something starts to grow or
it builds up copper stuff that clogs the filter. Also set the reset to
auto-reset or else whenever the building has a chilled water hiccup, it will
turn off. Other than that, these have been quite reliable. The company has
also been really helpful the 2 times we've needed them over the years.
. I found back the paperwork on our 800 CP, but keep in mind we've had this
since 2005. This one is a Model R300 refrigerated, water cooled to cool a
Varian helium compressor. We have essentially the identical unit for our
Bruker 700 CP that came with the instrument (donation). So, we did not
explore trying to use one heat exchanger for both and the instruments are on
far sides of the lab from each other. Water cooled condenser, 3.5 gpm,
all-bronze turbine pump, Model R300 (208/230V-3-60Hz). I scanned the spec
sheet into a pdf. I do think you can use one chiller to run multiple
probes.
3) I have a water-air system. The water chiller cools the probe and then
dumps the heat outside of the lab into the hallway. I have the advantage
that my building was built about 12 year ago and has an excellent system for
monitoring heat within the building. For me the water-water option was not
great, because of installation cost and our in-house water chiller has a lot
of crap in it (ie prone to clog). I use 75% h2o:ethylene glycol in my Neslab
CFT-300D. This keeps the Cu erosion down. I was running 50:50 but lost the
pump and decided to change my ratio. It works well.
4) We have a water-chiller for a cryoprobe on a Bruker 800 MHz NMR
spectrometer. It was installed, but we have never used it because we changed
the water-cooled HE compressor to air-cooled compressor.
5) We have water-cooled chillers from Haskris which run off the secondary
chilled water loop for the building that our Bio-NMR lab is located in. The
problem is that there are frequent thunderstorms in the Houston area that
lead to temporary electrical outages. Everything in my lab is UPSed and/or
on emergency power (we have a hefty diesel generator that takes care of a
lot of other things in the building, mostly -80 C freezers in some of the
biology labs). Unfortunately, the pump that drives the building's 2nd-ary
chilled H2O loop is NOT on emergency power, and it's a 5 story building! So
any outage that's longer than a blip causes the flow in the 2nd-ary chilled
water loop to grind it a halt (that's probably a mixed metaphor, "water"
doesn't usually "grind") -> Haskris heats up, shuts itself off -> helium
compressor heats up, shuts itself off -> cold probe warms up. It's
essentially the kink in our armour, our Achilles heel, if you will. In
retrospect, an air-cooled chiller might have been a better bet, they only
need power; however, 1) they need a LOT MORE power than a water-cooled unit,
2) they're really LOUD and HOT, and 3) they may cause more vibrations. For
reasons 2) and 3), it's a good idea to locate them as far away from your
system/lab as you can. (War story #327: UT Medical Branch down in
Galveston had an air cooled unit outside their lab which worked pretty well,
until Hurricane Ike came along and drowned the thing.) I would talk to your
facilities/building people: if you're thinking of going w/ a water cooled
unit, find out how frequently (hopefully, it's INFREQUENTLY) the secondary
chilled water loop goes down (either planned or unannounced). I think some
places they'll run the water-cooled chillers off tap water, but that's a lot
of water, you have to set up a drain system, and if the water quality is not
the best, it'll necessitate filtering.
6) I have a Haskris R300 chiller for Bruker's water-cooled Helium
compressor. It works very nice. When we warmed up the CryoProbe for
annual service, we also had the Haskris serviced (change filter, general
cleaning).
. I am attaching an old Haskris_Brochure file, which is few years old. You
should be able to get a more recent one by contacting Haskris directly
(www.haskris.com).
Basically, R300 requires 208V (either single phase or 3-phase). I do have a
30KVA UPS in my lab to support all NMR's as well as the Haskris and
CryoPlatform.
7) I don't know if you're planning on using a closed loop chiller or not but
that would be my recommendation. The one that I had that used house chilled
water was a continual pain in the butt. Physical plant never bothered to
call when they were going to mess with the chilled water, etc. I'm sure you
know what I'm talking about. I've had a bunch of Haskris closed loop
chillers and they've been pretty robust and problem free. Currently, I've
got two Sumitomo systems on my Bruker 500 and 600 MHz systems that are air
cooled for interior spaces. We've got space in the interstitial and no one
cares how much heat I dump in there (fortunately).
8) At L.S.U. we have a Varian 700 MHz spectrometer with a cold probe. I
purchased a Haskris Model R300 unit which is a 3 horse power unit. I
learned of them after speaking with researchers in the chemistry department
who have used Haskris products for quite some time, for other applications.
In general I am pleased with the performance of the device. However, had I
a choice as to where I put the chiller I would have located it anywhere but
where I put it. My chiller is in a mechanical room owned by facility
services on campus and is full of boilers and heavy electrical panels. This
translates to one very hot room, often well over 100 degrees. As a result,
I have had to replace the refrigeration compressor twice over 5 years, most
recently on Monday of this week.
When I was at the stage you now find yourself I phoned Haskris and explained
what I was trying to do. Fortunately he was very familiar with Varian cold
probes and made some recommendations that were somewhat different from my
original plans, and he was right. I don't have a cryo probe on any of my
Bruker instruments so I am not able to comment on how knowledgeable they
would be but my suspicion is that they would be equally as knowledgeable
about Bruker applications.
.Electrical Characteristics: 208/230V 1-phase; Total Full Load Current:
26.6 amps; Refrigerant: R22; Water Temperature Setting 65-69 F; Water
storage capacity 14 gallons.
I don't have the physical dimensions handy but it is approximately 46 inches
tall, 46 inches long and 38 inches wide, if my memory serves me correctly.
As water chillers go, this is not a large one and I am not certain that this
unit would handle more than one cold probe. Indeed the unit was chosen so
that it would adequately handle this particular probe, with a bit of a
cushion but not to be excessively large. Undoubtedly there are larger units
available that would handle two or three cold probes. Where I in your
situation, though, I might approach the problem from a different angle.
Even if it is more expensive to have two or three smaller chillers than to
have a single large chiller, think about how much disruption your facility
will endure when this unit fails. If you are running three cryo probes off
of a single chiller, when it fails, three probes are going to be out of
service, rather than one. That is a problem that I would try very hard to
avoid.
9) We have an INDOOR HASKRIS WATER CHILLER type R300-CR to cool the helium
compressor on the cryoprobe of our Inova600. This is a refrigerated water
chiller with a water cooled condenser which is hooked into our buildings
cooling loop. I have no complaints about the system - it was installed in
2003 and has been on ever since with no maintenance or downtime so far.
10) We studied this issue, and decided to cool our cryo-compressor with the
campus tap water. To cool one compressor with another compressor was deemed
seriously inefficient, since it added another layer of mechanical operation
and maintenance. Instead, we run the tap water through 10 micron, then 1
micron particle filtration before using it to cool the cryo-compressor, then
waste to drain. As a result of this scheme, we must change our water
filters every 6 months, and backflush the compressor heat exchanger with
cleaner yearly. Tap water consumption is approx. 2 gpm.
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