Dear Brendan,
Amber latex rubber tubing is most frequently used for filling liquid nitrogen and is available from general lab supply companies such as Fisher Scientific, VWR and Daigger. Choose an inner diameter that fits securely but not too tightly onto the liquid nitrogen fill port of your magnet and a wall thickness of 1/8" or more. At the liquid nitrogen tank end, you can attach the rubber tubing to a piece of copper or stainless steel tubing with a flared end and nut to accommodate the fitting on your tank. Since this tubing is translucent, you can monitor the flow of liquid nitrogen by holding a flashlight up to it while filling. Because latex tubing has a finite shelf life, check the tubing carefully for cracks before putting it into service. Eventually, this tubing can crack while filling, creating a potential safety hazard. For safety, we enclose the latex tubing in thick foam pipe insulation (available at any hardware store or from industrial suppliers such as McMaster-Carr Supply Company or Grainger), which will contain any shards of frozen tubing and any leaking liquid nitrogen resulting from splitting of the tubing. Finally, in order to reduce strain on the rubber tubing and to allow some movement during filling, we use a composite design in which the rubber tubing is connected to a short length of flexible stainless steel hose equipped with an armored jacket. The stainless steel hose has a permanently attached fitting which connects to the tank and the entire assembly is sheathed in foam pipe insulation. Since the stainless steel hose remains flexible even at liquid nitrogen temperature, it can relieve strain that could otherwise crack the frozen rubber hose. Please let me know if you have any questions about this setup.
Best regards,
Ken Fishbein
Kenneth W. Fishbein, Ph.D.
Facility Manager, MRI Section
National Institute on Aging
National Institutes of Health
251 Bayview Boulevard
Suite 100, Room 04B120
Baltimore, MD 21224
(410) 558-8512
FAX: (410) 558-8376
Kf31x_at_nih.gov<mailto:Kf31x_at_nih.gov>
From: Duggan, Brendan [mailto:bmduggan_at_ucsd.edu]
Sent: Monday, January 13, 2014 5:56 PM
To: ammrl_at_ammrl.org
Subject: AMMRL: Liquid nitrogen transfer lines
I inherited several braided metal liquid nitrogen transfer lines when I took over my current lab and now prefer them to the light brown tubing I have used everywhere else. Unfortunately, most of these transfer lines are leaking where the braided hose meets the metal couplings at the end. Does anyone know if these can be repaired? Alternatively what is the light brown silicon/rubber type material that is often used to transfer nitrogen, and where can I get some?
Brendan M. Duggan, PhD
NMR Facility Director and Associate Project Scientist
Skaggs School of Pharmacy and Pharmaceutical Sciences
University of California at San Diego
9500 Gilman Drive, MC 0684
La Jolla CA 92093
office phone: (858) 534-8763
lab phone: (858) 822-7826
cell phone: (858) 692-2298
email: bmduggan_at_ucsd.edu<mailto:bmduggan_at_ucsd.edu>
http://sopnmr.ucsd.edu
Received on Tue Jan 14 2014 - 09:17:21 MST