Dear Vernon Russell,
In addition to all the good answers, I would like to add a method to clean
the probe. This will remove small reasons of arcing from the probe.
An Isopropanol bath to the stator part of the probe.
I secure the probe upside down and dip it inside a large 1 to 2 L plastic
beaker where the isopropanol is filled until all the stator is immersed inside
the liquid. Please not the outside cover of the probe is removed and you
can see the stator.
Slush the beaker slowly and occasionally for about 15min. Take out the probe
from above or the beaker from the bottom. With a squirt bottle spray clean
isopropanol onto the stator and surrounding space. The probe can drip into
the already dirty beaker. Use pressurized, dry and clean air or N2 to dry out
all the left over liquid from the stator area. Attach the probe to all the
probe flush, bearing and drive gas lines (no sample), open all the valves with
low amount of gas (B=D=F=500mBar or less) and wait for 5-10m in. Don't
forget to clean the inside of the probe cover with isopropanol too, this will
increase grounding contacts. After this try using the probe with a clean rotor,
use a tissue to hold the rotor making sure that there is no finger oil on it.
If you are using pressurized air for the experiments please check the oil content
in it and replace your oil filters. You might need to upgrade the filtering
system as well. If oil in air is the real problem you need to observe your probe
before the cleaning process. Look at the “insert” (a CL unit)
right under the stator compartment where the probe flush gas is blowing. If
there is any color change, shininess due to oil etc. When there is oil, the
inside of the probe cover also gets oily.
With kind regards,
Rıza
-------------------
Rıza Dervişoğlu, Ph.D.
NMR Lab. Coordinator at Wiegand Lab.,
Max Planck Institute for Chemical Energy Conversion,
working at ITMC, RWTH, Aachen,
Tel.: +49 (0) 241 80 26429
Address:
SB Chemie
Room: 38B-031
Worringerweg 2
52074 Aachen, Germany
https://mpi-cec.webex.com/meet/riza.dervisoglu
https://www.linkedin.com/in/rizadervisoglu/
ride_at_cec.mpg.de
> On 16Apr, 2024, at 19:48, Tom Pratum <tkp9551_at_gmail.com> wrote:
>
> Sometimes, but not always, you can see arcing by looking at the power
> reflected from the probe on a scope. If you do see it there, then that is
> confirmation, but if you don’t it doesn’t necessarily
> mean it isn’t arcing.
>
>
> Tom Pratum, SOU
>
>
>> On Apr 16, 2024, at 6:18 AM, Vernon M Russell via groups.io wrote:
>>
>> I’m getting sporadic spikes in the fid while running a cpmas
>> sequence on a Neo (2.5 mm cpmas probe). I’ve tried easing up on the
>> various power levels and pulse times but the sporadic nature makes this
>> difficult to track down. Adjusting the spinning speed does seem to help.
>> Does anyone have a general troubleshooting guide to see what is causing
>> such spikes?
>>
>> Thanks,
>> Vernon
>>
>> Vernon Russell
>> vrussell_at_wlgore.com
>> W. L. Gore & Associates, Inc.
>> Together, improving life
>> 501 Vieve's Way, P.O. Box 1320
>> Elkton, MD 21922-1320
>> USA
>> gore.com <http://www.gore.com/>
>>
>>
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Received on Wed Apr 17 2024 - 10:36:58 MST