Dear All,
We have used copper tubing (for plumbing, cost $1) for N2 transfer, tipped
off with several inches of silicone ($2) tubing to allow a flexible (when
warm) coupling to the fill port, for many years without incident. The copper
tube is insulated with a flexible polyurethane foam sleeve (cost $1). The
only "added value" step is to place a threaded fitting on to the tube (to
attach the tube to the nitrogen dewar outlet valve) and flange the copper to
make a snug fit over the valve tip. This construction lasts indefinitely
(you may need to replace the silicone tubing if you put strain on it
prematurely) and has a very rapid cooldown time. Fills can be very rapid due
to the virtual absence of pressure-sensitive points.
Best Regards
___________________________________
Dr Iain B Cook
Anexus Laboratories
41 Greenaway Street Bulleen
Victoria Australia 3105.
ABN 68005912612
Mob 0438 780 188
Ph (613) 9850 4708
Fax (613) 9850 9733
e-mail icook_at_anexus.com.au
website www.chemicalanalysis.com.au/
e-mail icook_at_chemicalanalysis.com.au
(home e-mail icook_at_bigpond.net.au)
___________________________________
-----Original Message-----
From: Bill Stevens [mailto:wstevens_at_siu.edu]
Sent: Saturday, 21 June 2003 9:38 AM
To: camass
Cc: AMRRL Mailing list
Subject: Re: More on latex tubing
At 03:41 PM 6/20/03 -0400, camass wrote:
>dear group,
>given the cost of an nmr i seem to be missing the point of using latex
>vs a braided stainless hose. i have used latex but find it a pain. if
>necessary (not desirable) you can remove the stainless hose while cold
>and it presents no dangers i know of.
I can write to that point. When I was a postdoc at UAB, learning to be an
NMR manager at the knee of one of the best, Dee Huang, we had a stainless
steel hose.
I often helped with fills and one day discovered that our stainless steel
transfer tube was not ours and had been reclaimed by its owner. I
jury-rigged a transfer line of 3/8" copper tubing and was astonished at how
much faster the fills went. I concluded then and still believe that the
mass of the stainless steel apparatus resulted in much waste to keep it
cold.
I could be wrong, but my recollection is that fill times were cut by 2/3.
Bill
William C. Stevens, Ph.D. NMR Facility
Director Southern Illinois University
Carbondale, IL 62901-4405
618-453-6498 fax -6408 U.S.A.
http://opie.nmr.siu.edu/bill.html
Received on Tue Jun 24 2003 - 13:53:50 MST