Re: wet vt air
Jim Breeyear (jbreeyea@zoo.uvm.edu)
Thu, 23 Jan 1997 16:29:53 -0800
John Chung wrote:
>
> howdy
>
> it's raining on the west coast, but i'm more concerned today about
> a sudden icing up of vt air chillers on our spectrometers, most
> likely caused by our compressed air being wet.
>
> i need some help/input into figuring out what to do about it.
>
> three separate machines using Bruker's new BCU05 seem to be icing up
> when the chiller is on, and the vt heater current shuts off because
> the air flow meter goes to zero flow. turning off the chiller and
> cranking up the air pressure for 15-30 minutes seem to break the ice
> in the line and flow is reestablished, but the problem has been
> repeating itself since the last weekend some time.
> one other machine with an older immersion cooler seems to be having
> vt air pressure fluctutions (as seen by the ball flow meter on
> bruker's vtu2000), but two other magnets with older chillers do
> not seem to be having any problems with temperature control, no
> icing up....
>
> we're in a brand new building with Hankison air dryers (which seemed
> like overkill for the job and had shown no signs of malfunction so
> far), and the two moisture indicators in the line in the compressor
> room right before transfer into the magnet room are indicating
> all thing are normal. since august these have performed w/o any
> problem.
>
> in another room with one more spectrometer which has its own
> balston dryer, there seems to be no problem (although this one
> is fed through an extra nitrogen generator which further takes
> water out of the line, most likely)
>
> since all signs seem normal and i'm not sure how to proceed,
> I'D LIKE TO KNOW IF ANYONE OUT THERE HAS A WAY OF "QUANTIFYING"
> THE AMOUNT OF MOISTURE IN YOUR COMPRESSED AIR.
> and by this i mean something i can rig up myself and not go
> and buy a fancy measuring device which for one would take too
> long...
>
> or if any of you have any suggestion on what to do other than
> running all vt off our nitrogen generators (which i have done for
> two of the machines for now), since the nitrogen generator itself
> is fed the same air and is probably not as dry as we'd like
> if indeed the inlet air is wet.
>
> thanks for your help.
>
> John Chung
>
> *************************************************************
> Manager, NMR Laboratories (619)784-7453 (Office)
> Dept. of Molecular Biology, MB2 784-7455 (Lab)
> The Scripps Research Institute 784-9822 (Fax)
> 10666 N. Torrey Pines Rd. email: chung@scripps.edu
> La Jolla, CA 92037 http://www.scripps.edu/~chung
> *************************************************************
Hi John,
I am glad to hear that someone else has similar problems.
Our air dryer is supposed to be able to supply -40 centigrade dewpoint
air to our septrometers when at the proper supply pressure of 100psi.and
fed with the proper size line.
I ran a line from the dryer to the infra-red spectrometer for purge and
do a water check. It seems to be the easiest way.
If I dont like the level of water for a specific experiment then I buy a
liquid nitrogen pressure builder and that lasts for almost a week. I
also do all the real low 100kelvin work with a nitrogen tank for spinner
and lift air for obvious reasons.
I put the usual oil and water filters on the lines before the dryer.
I also built an enclosure for the bottom of the magnet to enclose the
probe, etc. I purge that area with nitrogen gas also. Makes for less
mess and icing. I use a BVT-2000 v.t. unit.
Good luck!
Jim Breeyear
Univ of Vt
Manager Inst center.