Hi All,
I am not sure that I have seen anyone mention using a combination of soft
copper tubing and a short length of latex line for filling magnets. I had
a long length of red rubber vacuum tubing split from one end to the other
during a fill and stopping using that tubing after that event. At that
time I had been using a short length of soft copper tubing (about 3/8
inch ID bendable solid copper line, used for refrigeration lines) to fill
our VT dewar so I made a longer line for the magnets (those were unshielded
then).
You can fit one end with a flare nut fitting for the supply tank (machine
shops will generally have the flaring tool) and the other end with about a
1 foot long piece of latex tubing (the magnet end) to allow for the
connections. I am using that here now with two shielded magnets and it
works well. I have made specific lines for each magnet. You do have
to get the supply tank into the correct location within a few inches. I do
take care to be sure to have a nice gentle radius bend on the latex to
minimize stress and I hold that part until it freezes. I have insulated
the copper line with standard pipe insulation (the grey foam type). The
lines cool down fast and when insulated have a lower heat loss so the fills
are shorter and consume less LN2. It is a cheap solution and seems to
provide some measure of safety since any failure of the tubing should be at
least a few feet away from the tanks supply valve. As a disclaimer, there
is still the risk of breaking the latex line with this method and that can
be dangerous.
I always wear gloves and glasses while filling and I replace the latex
section (Fisher part number 14 178 5F) about once a year.
I have seen LN2 burns and they can be very bad.
Regards,
Joe
*******************************
Joe Dumais, Ph.D.
Associate Research Professor/Nuclear Magnetic Resonance Spectroscopist
Boise State University
College of Arts and Sciences
Department of Chemistry and Biochemistry
1910 University Drive, Boise, Idaho 83725-1520
(208) 426 4913
http://chemistry.boisestate.edu/
*******************************
On Tue, Dec 2, 2014 at 12:39 PM, Joseph Sachleben <jsachleben_at_uchicago.edu>
wrote:
> Hi All,
>
> I remember a few months ago there was a discussion about liquid nitrogen
> fills. I have always used latex tubing to connect the nitrogen
> dewar to the magnet. Some of you mentioned that you used stainless steel
> l-N2 transfer lines to do the fills. The question I have is how
> do you connect the stainless steel transfer line to the magnet.
>
> Thanks,
>
> Joe
>
> Joseph R. Sachleben, Ph. D.
> Technical Director Biomolecular NMR Facility
> The Division of Biological Sciences
> 929 E. 57th St.
> Chicago, IL 60637
>
> (773)834-9866
> jsachleben_at_uchicago.edu
>
>
>
>
>
Received on Wed Dec 10 2014 - 13:14:14 MST