Well,
I can't say we've all seen it, but it is not uncommon. Going forward, I
would suggest that you crack the low pressure vent a little, and release
the pressure as slowly as can be tolerated. You will lose less helium that way.
As far as a FedEx delivery goes, they'll do whatever is cheapest to accomplish.
A 100 liter dewar does not require a placarded transport......as long as required
paperwork is present.
John \\\
________________________________
> From: main_at_ammrl.groups.io on behalf of Quinn Kleerekoper via groups.io
> Sent: Saturday, May 10, 2025 10:42:54 AM
> To: main_at_ammrl.groups.io <main_at_ammrl.groups.io>
> Subject: Re: [AMMRL] Helium Delivery-Safety Valve in off position
Brian,
When you speak of the helium safety valve are you referring to the 1/4 PSI
pressure release valve that has a manual shutoff valve? There should be
another pressure release valve (10 PSI) without a manual valve. If the dewar
doesn't have this I would be shocked, Is it a Cryofab dewar? As long as you
have the 10/15 PSI pressure relief valve there is no danger outside of the
annoyance of having to release the excess pressure by cracking the valve that
controls the 1/4 PSI valve. If you just crack it you can prevent the massive
loss of helium both gas and liquid.
Quinn
On Sat, May 10, 2025 at 8:55 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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