Yup, it happens!
My department's research NMR was installed in 1993 and the magnet has not be overhauled in all the years since. Well, even borrowed time runs out. For us this happened some time between Saturday night and Sunday afternoon. The magnet quenched and this morning when I came in the top and bottom of the instrument were covered in frost ice. After seeing if the magnet was gone I called the company that helps me with service. Since I could not find this info on the web I offer this list of things to do if your magnet quenches if it is going to be a while until you can come up with the scratch to bring it back up. (California still doesn't have a budget when the year started July 1.)
1. Shut down the console.
2. Pull the probe from the magnet if you can. If it is frozen in place, don't force it.
One thing I should have thought about is that it would be freezing cold. I darn near frozen my hand to the side of the probe when pulling it.
3. Pull the shim stack from the magnet.
I have pulled it before to clean the spin assembly. There is a ring clamp that holds it at the bottom and three long screws that hold it from the top. It has generally been pretty snug and required some pressure to pull it down. Well, with everything frozen the bottom clamp does not hold it. It almost dropped to the floor when I took out the three screws at the top of the magnet. Fortunately I had someone there "just in case".
4. Last, I removed the upper stack.
Now, I need to find the money to replace the seals and bring back the magnet.
T.S. Hall
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Sounds like it's time to transition to NMR simulation. Hey, we know how these experiments are supposed to come out anyway, don't we?
ReplyDeleteYeah, I bet JOC will be accepting simulated spectra of the compounds that should be produced in the reactions that prove my research hypothesis in support of my papers any day now.
ReplyDeleteT.S. Hall
Ouch! Certainly one of my worst nightmares. I hope there is an understanding chem dept in the area that can give you some NMR time in the meanwhile.
ReplyDeleteI'm curious about who you are using for repairs.
Would you mind emailing me the name at drwrw at me.com?
Thanks!
I don't mind posting the info here.
ReplyDeleteThe magnet is from a Bruker AC series instrument, but the console on the instrument is from Tecmag out of Houston. We were already discussing moving the instrument with them, so we will have them do the this work.
I also work with NMR Associates out of the Boston area of Mass. for repairs on our teaching instrument.
I can recommend both companies. They have both been great in answering questions and guiding me with in-house repairs. I barely passed the electronics part of physics and they have even instructed me on how to use our digital oscilloscope over the phone.
T.S. Hall