Hi Walt,
How old is your RT probe? If its a pre-2010 (ish) probe with the old-style
ball-type connector then it'll be what Bruker calls the "Flow-Turn" type
(described in the VT manual), which doesn't have a bypass for the VT gas, and
so doesn't tolerate as high flow VT gas flow rates. On my 2008-vintage RT
BBFO you can just about get away with 535 lph, but adding spinning on top
of that pushes it over the edge and starts to lift the sample up and triggers
the emergency eject message. 400 lph is the standard flow rate at RT for
this particular probe. IIRC cryoprobes generally (definitely He, not so sure
about N2) use a higher gas flow rate so perhaps you've just transferred over
this from the old parameters?
Thanks
Geoff
________________________________
From: main_at_ammrl.groups.io <main_at_ammrl.groups.io> on behalf of Michael Groves <m.groves_at_utah.edu>
Sent: Friday, July 14, 2023 16:24
To: main_at_ammrl.groups.io <main_at_ammrl.groups.io>
Subject: [External] Re: [AMMRL] cryoprobe emergency eject troubles
Hi Walt,
Sounds like you busted it good ...
Seriously, though, there are several things that could cause this. Here are
a few in no particular order:
If the VT gasflow is a bit too high and sample spinning is turned on, it can
lift the sample enough that "sample down" signal is lost and the sample changer
thinks the emergency lift is on.
If the sensor at the bottom of the BST (the upper section of the shim stack
is getting dirty, the SampleXpress could think that the sample is lifting and
throw that error message. Based on the age of the system and the fact you've
got a sample changer, I would probably check this first. Depending on how
well people clean their samples, dirt tends to build up. Some people have
had success using a long wooden dowel and some sort of wipe to fashion a giant
swab to clean out the shim system. If you want good instructions for this,
I'd get in touch with Bruker Center (center_at_bruker.com<mailto:center_at_bruker.com>).
It could be a faulty SPB. Sometimes the valves in these fail in interesting
ways and instead of smoothly regulating the VT gasflow you get random spikes.
Which could result in the sample lifting enough to cause the emergency eject
error. This might also be caused by some sort of intermittent leak - it's
probably not a bad idea to go over the VT gas connections to make sure there
are no leaks and that the tubing hasn't become brittle.
There's a short cable that connects the samplexpress to the shim system.
That could be failing, but I think that’s the least likely alternative.
You could always disconnect it and reconnect it.
Cheers,
Mike
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Received on Fri Jul 14 2023 - 09:20:16 MST