Hi Eugenio,
Normally the 250lph gasflow is plenty low enough to allow the sample to seat.
There are a couple of things that come to mind:
Is the sample really descending or is it getting caught at the interface between
the sample transport and the shim system? If that gets a little bit out
of alignment you can start getting things caught there. If it gets past
the interface and really is dropping down into the magnet then it's likely
not an alignment issue.
Do you have a cryoprobe? Is the emergency VT gas connected? If
so, you might try disconnecting that from the input to the probe. (if
it's there, there's a one-way valve and then an adapter and then the tubing
to the console. Just pull the tubing out--leave the one-way valve
installed. If the emergency VT gas is too high then it can keep the
sample from seating properly.
I believe there's a timeout that you can adjust in the BSMS service webpage
that will increase the time it waits for the sample to seat--you could try
increasing that to see if a longer delay (60s? Longer?)
Is the VT gasflow really being decreased? If you open edte and watch
the gasflow, and then insert a sample, does it really drop to 250lph?
And, there have been cases where people have overheated their spinners and
they go out of round. One possibility would be to take each spinner
that fails out of the rotation. That way you can see if the failures
really are random or if there is some group of spinners that just doesn't
want to insert correctly.
That's what I've got.
Cheers,Mike
On Tuesday, December 16, 2025 at 01:53:40 PM MST, Eugenio Alvarado via groups.io wrote:
Dear all,
Recently, our Avance Neo 500 with a SampleCase is having more frequent
random issues with about 10% of samples that don't seat completely
inside the magnet. The samples lift and descend properly in the magnet
but sometimes they just don't settle down properly, even after a delay
of 30 or 45 seconds, causing IconNMR to eject and try inserting the
sample several times until it gives up. When that happens, not only
that sample fails, but also the next one in the queue, probably because
its start time has timed out after the previous attempts. The gas flow
pressure in the console is set at 4.5 bar and I just changed the "VT gas
flow limitation" in the BSMS Web Services interface from 700 to 250 with
just a little improvement. The VT gas flow in standby is
40 l/h and for operation it is 400.
Can anyone please suggest any other parameter to adjust to make sample
insertions more reliable? Or could it be a problem with a valve?
Thanks in advance,
Eugenio
--
Eugenio Alvarado, Ph.D.
NMR Facility Director
Chemistry Department, room 3500. University of Michigan
930 N. University Ave., Ann Arbor, MI 48109-1055.
Voice: (734)-764-9924
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Received on Tue Dec 16 2025 - 15:21:59 MST