Hi Greg,
Firstly, thanks for your response. I can recall that both towers iced up at
the end, similar to fills before this issue started. However, I can vaguely
remember that the tower on the non-filling side started frosting first as
it normally does but I am not 100% sure. We know for sure that the problem
is not with the transfer line or the dewar as it was not reproducible with
other helium dewars or magnets using the same transfer line.
If you don't mind me asking a few details:
What was the % helium level when you purged the can with warm helium gas?
You mentioned you do it right before the fill but how low did you let
the level go?
Did you use He6 for the gas flow or the regular lower purity
helium cylinder as your source?
What was the approximate gas flow rate?
Many thanks in advance.
Best,
Hasan
On Fri, Aug 22, 2025 at 6:44 AM gregory.wylie via groups.io wrote:
> Hi Hasan
>
> Do you recall during the fill if both helium towers were frosty? And did
> the non-filling side frost first? The blockage could be on that side not
> the fill side. Another possibility would be a blockage in the transfer
> line. That would cause I higher tank pressures but lower exhaust from the
> magnet.
>
> Blowing helium gas into the magnet is how I have cleared blockages in
> past. I have used the standard L-tubes and specialty made things as well.
> It is always nerve racking to do this, but can be done. I usually do it
> right before the fill.
>
> Greg
>
> Gregory P. Wylie, Ph.D
> NMR Facility Manager
> Texas A&M University
> Department of Chemistry #3255
> 580 Ross St.
> College Station, TX 77843-3255
> gpwylie_at_tamu.edu
> 979.458.0705 (voice)
> 979.845.4719 (fax)
> 706.206.0007 (cell)
> http://nmr.tamu.edu
>
>
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Received on Mon Aug 25 2025 - 11:21:55 MST