Dear Weiguo,
We have also been having strange problems with our 4mm CP/MAS probe, perhaps
not dissimilar to yours, so please provide a summary in due course if you
are able.
Our problem:
Initially the eject would not work at all and clearly lots of gas was coming
out of the bottom of the probe when eject was engaged. After removing the
probe cover it was found that the eject line had become disconnected at the
junction half-way up the probe (why is there a simple connection there ? why
not just continue to tubing ?), fair enough it was not working. So the tubing
was reconnected, but to say that the re-connection was dubious is an understatement.
Anyway, after re-inserting the probe the eject did not work so obviously the
re-connection did not hold. Or so it was thought. So not to bother with it and
just take the probe out to retrieve samples. Later, due to another problem
(a cap had come off so we needed to check for sample in the probe), the cover
was again removed and. low and behold, the connection was still in place.
What ??? Anyway, after replacing the cover and reinserting the probe we have
the habit of first inserting with no sample and then ejecting (no idea if this
helps, I was just told that it does somehow ...), and surprisingly the eject
sounded normal (as opposed to insufficient flow going up the delivery tube).
So after the run, when eject was engaged, it worked as it should and the sample
was ejected up the delivery tube.
Thoughts anyone ?
Thanks to all,
K. Klika
________________________________________
> From: weiguo.hu_at_mail.pse.umass.edu <weiguo.hu_at_mail.pse.umass.edu>
> Sent: 07 October 2024 17:24:41
> To: main_at_ammrl.groups.io
> Subject: [AMMRL] AMMRL: Bruker MAS probe rotor ejection problem
Dear Colleagues:
We have a 4mm CP/MAS VTN probe that has a problem. We usually set the EJ gas
to ca. 30% and the ejection usually works well and the rotor comes out with
not too much of a force to bang against the rod ceiling. In recent months,
however, occasionally the ejection action would not activate upon clicking
the eject button on the MAS control. I would need to increase the eject
pressure to ca. 60% to get the ejection going again, then lower it back to
30% and it will behave for a while. However, the ejection gas pressure needed
to re-activate the action has been increasing over time and now even with
eject gas at nearly 100% the ejection action would not kick in. I suspect
that one of the gas tubings in the probe might be aging and losing flexibility
which might have caused this problem. I wonder if anybody has done some
research about this problem and can share some wisdom.
Thank you,
Weiguo Hu
Director of NMR Labs/Chemistry & Materials
Conte Polymer Research Center
120 Governors Dr
University of Massachusetts
Amherst, MA 01003
-=-=-=-=-=-=-=-=-=-=-=-
Groups.io Links: You receive all messages sent to this group.
View/Reply Online (#1720): https://urldefense.com/v3/__https://ammrl.groups=
.io/g/main/message/1720__;!!PvDODwlR4mBZyAb0!WSv8euWasG6XDFf1O71RBT0ko8TA3O=
qU0YqHEmhXkrtfSvKOP0UDcpKN-S57sK9CWg-A6e0KPs5jXQ$
Mute This Topic: https://urldefense.com/v3/__https://groups.io/mt/108868672=
/7559972__;!!PvDODwlR4mBZyAb0!WSv8euWasG6XDFf1O71RBT0ko8TA3OqU0YqHEmhXkrtfS=
vKOP0UDcpKN-S57sK9CWg-A6e1MvMGvPQ$
Group Owner: main+owner_at_ammrl.groups.io
-=-=-=-=-=-=-=-=-=-=-=-
Received on Mon Oct 07 2024 - 08:07:50 MST