wet vt air

John Chung (chung@scripps.edu)
Thu, 23 Jan 1997 10:43:26 -0800

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
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