Hi Sebastian,
When we first started using our recovery system, the unexpectedly large
amounts of gas created by filling magnets or transferring helium from
the plant into a transfer dewar shocked us.
It's different for every magnet but typically if I put 100L into a
magnet (meaning: the volume of LHe in the transfer dewar decreases by
100L during the fill), I typically recover around 30 liters of
liquid-equivalent as gas. That's about the average - it can be
significantly higher than that depending on the magnet. And it reliably
scales with the size of the fill. If I fill 30 liters, I'll recover 10
or 12 liters as gas.
But a bag of 10-12 m^3 should be enough (depending on the details of
your system). My recovery bag is only 8.5 m^3, and I do fills of up to
120L. I manually trigger the recovery compressor just after I start the
fills, so it starts removing helium from the bag when it's still close
to empty. Even so, with certain magnets and large fill volumes, the bag
can fill all the way up and start releasing helium through the pressure
relief valve. So I keep an eye on the bag during the large fills
(running back and forth between rooms), and sometimes I've been forced
to stop the fill early or pause it to allow the bag to empty enough to
continue. (A transfer line with a shutoff valve is necessary for this
sort of thing)
But if your system is similar to mine (Cryomech LHeP28), you should be
fine with a 10-12 m^3 bag and fills of 80-90 liters.
-Robert
On 2025-07-29 05:30, Sebastian Kemper via groups.io wrote:
> Hello everyone,
>
> I would like to modify my helium recovery system so that I can collect
> helium during the filling procedure. Due to the relatively limited
> space, I have a few questions about balloon size and compressor
> performance and I would be very grateful for any experience from
> colleagues so that I can purchase the right equipment.
>
> - How much helium will be produced with a fill of 80-90 liters? I
> calculated for 80 liters with a fill loss of 15% that max. 16 m³ will
> be released during the fill (assuming the cold replaced gas will warm
> up from 4 K to 298 K). What are the real numbers? Are there any
> empirical values?
>
> - I probably only have space for a balloon of 10-12 m³. Do you have a
> setting where the compressor starts during filling and compensates for
> a balloon that is ‘too small’? A colleague told me, that it is
> possible, but I don't want to miscalculate and it would be very
> helpful to hear about other cases. If you have such a setting, what
> size balloon do you have? What is the compressor's flow rate? At what
> percentage of the balloon volume does the compressor activate?
>
> Best regards,
>
> Sebastian
>
>
-=-=-=-=-=-=-=-=-=-=-=-
Groups.io Links: You receive all messages sent to this group.
View/Reply Online (#2606): https://urldefense.com/v3/__https://ammrl.groups=
.io/g/main/message/2606__;!!PvDODwlR4mBZyAb0!TBQelgDh0Mq3uI_TJ9m8jqfRa1oRJW=
HlvXCXduTE2S6yzPpbF1cnlpezgVmiEzdoZhLZmCPvfuGtIBAKWHMskE__CX1r$
Mute This Topic: https://urldefense.com/v3/__https://groups.io/mt/114436217=
/7559972__;!!PvDODwlR4mBZyAb0!TBQelgDh0Mq3uI_TJ9m8jqfRa1oRJWHlvXCXduTE2S6yz=
PpbF1cnlpezgVmiEzdoZhLZmCPvfuGtIBAKWHMskJOMe6Ir$
Group Owner: main+owner_at_ammrl.groups.io
-=-=-=-=-=-=-=-=-=-=-=-
Received on Tue Jul 29 2025 - 17:48:44 MST