Hi Piotr,
If it is transferline problem,
Could you check the current vacuum in the line by looking at the reading from
the vacuum pump. Pump it overnight or so. Turn off the pump. Let the transfer
line sit for a period of time. Turn on the pump and look at the reading again.
It may give you some idea.
Good luck.
Simon
> From: main_at_ammrl.groups.io On Behalf Of Piotr Dobrowolski via groups.io
> Sent: Friday, July 12, 2024 11:11 AM
> To: main_at_ammrl.groups.io
> Subject: [AMMRL] Helium fill problem
Dear NMR Managers,
Recently, we started having problem with helium fill on our old (about 25
years) 500 MHz Inova. Transfer line precooling takes a little longer than
before (I think) but there is no water condensation on the line. However,
from the beginning of the transfer the pressure in the transport dewar (60 L)
is high. We try to keep it below 2 psi by setting low gas flow (about 2 L/min).
I guess because of that the fill takes very long time - about 1 hour to
transfer 50-55 L. Unfortunately, our Oxford helium level monitor does not
work. We just fill-up every 3 months.
I've been taking care of this magnet for more than 6 years and the fill was
always efficient (20-25 minutes) with gas flow set to 5 L/min (pressure 1.5-2 psi).
Transfer line vacuum was pumped last year.
Has anyone experienced such issue? Does this indicate transfer line or magnet
problem?
Thank you,
Piotr
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Received on Fri Jul 12 2024 - 11:47:09 MST