We have had many deliveries by FedEX over the years. Some of it delivered
overnight by air.
Technically they have to have the correct shipping label “un1963” on their truck.
They should open and vent the truck before going in to get the dewar. Helium is
more dangerous than N2 in this regard. As it is at the top and n2 is at the
bottom of the air space.
We have also received the occasional dewars with the relief valve closed.
After 30 years of doing this this adds up to a lot of dewars. My experience
is that these get to about 3 PSI, rarely higher. Venting these quickly
causes a rapid helium boil off as the temperate of the helium drops and more
of it starts to boil. Often when you open the valve there is a short period
with no plume and then the plume builds quickly aniindication of the increased
boil off and it is dramatic. Venting slowly is as an and less dramatic. But
it does take a while.
This boil off is related to the recent discussion on fills with helium recovery
systems. Sudden drops in pressure lead to rapid increase in helium boil off.
David
Associate Professor
Dept. Of Pharmacology
University of Colorado
School of Medicine
Tel (303)-724-3600
On May 10, 2025, at 7:12 AM, Roberts, Jessica via groups.io wrote:
Hi Brian,
I have received liquid helium from FedEx and agree in your sentiment about
how odd it is that they can transport it. I have not received a delivery with
the safety valve off though.
Cheers,
Jessica
Dr. Jessica M. Roberts, Ph.D.
Assistant Professor of Instruction
NMR Facility Manager
Department of Chemistry and Biochemistry
Ohio University
245 Chemistry
Athens, OH 45701
740.593.0038
jroberts_at_ohio.edu
--
On May 10, 2025 9:55 AM, "b-myers via groups.io" wrote:
Two days ago, while off campus, colleagues helped receive a 100 L dewar of
liquid helium. Today, I checked the dewar and found the safety valve off.
Opening it released a lot of pressure, so I opened the side vent, and a 2
meter jet of helium shot out for a few minutes. Thankfully, no one was near
the vent. None of the valves were shrink-wrapped, and my colleagues said they
didn’t touch them. I know the tank has blast safety burst caps, so
it’s unlikely it would explode, but it was disturbing. I am guessing
that if the burst cap had ruptured after we took the dewar, we’d have
had to replace the helium. It’s also strange that FedEx could
transport liquid helium.
In any event, I am curious to know if others in this group have received a
liquid helium dewar with the safety valve off? And is it common to get
deliveries of liquid helium by FEDEX (box truck)?
Brian
--------
Brian Myers, Ph.D.
Professor of Chemistry
Meyer Hall of Science (rm 256)
Ohio Northern University
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