Thank you very much for all the responses to my problem regarding NMR
tubes fitting loose in the sample holders.
It seems we are not the only ones with that problem.
The overwhelming opinion was that as long high quality tubes (like
Wilmad 528) fit, the problem is with the tube, and not the sample holder.
Also, several responders had experienced similar problems when using
economy tubes. In particular, the Wilmad economy tubes are rated with
a slightly lower OD (4.94665) than their regular tubes, (4.9635 ±
0.0065mm ) and have a larger tolerance.
One very helpful solution was to double up the O-rings at the bottom of
the sample holder to get a better grip. It was also pointed out that
one has to make sure to get the correct O-rings with sufficient
thickness. I my case I bought the O-rings from the Bruker webstore to
ensure that they are the right ones.
The solution with doubeling up the O-rings worked well in the case of
many of my loose tubes. I am also now requiring users to get a minimum
of Wilmad 507 or equivalent tube (Norell Select series S5300x, Aldrich
Precicion: Series 300, Kontest 235).
Thanks again
Holger
Received on Wed Jul 20 2011 - 11:36:31 MST