Thanks to all colleagues who send me their experiences and estimates. Indeed, there are quite a few cases where such things as
water lines,
A/C units or even O2 sensors were deep frozen by a quench and caused considerable damage. Generally, those were items directly
installed above the magnet or in the path of the quench gases.
I also managed to get a statement from the Bruker site planning people, essentially saying that:
- with a 600 MHz magnet, the quench gas temperatures are around 70 - 90 K,
- due to the low heat capacity of the helium gas, you need to blow directly from the quench valves etc. onto the pipes,
- any media flowing in the pipes will further reduce the risk of freezing,
- so you would need a distance of not more than 2-3 m to freeze a pipe,
- helium gas spreads fast over the whole room area under the ceiling, and then diffuses away. So the overall room temperature
drop will be barely noticeable.
(translated in my own words)
This fits well with my experiences during several quenches (from 600 to 900 MHz).
So I guess the conclusions are
1. be very careful with placing things directly above the magnet or into the quench path - danger of freezing / rupturing / cold
damage!
2. do not worry about cold damage of installations further away from the magnet or even outside the spectrometer room ( e.g. in
the ventilation ducts).
Thanks again,
gg
--
PD Dr. Gerd Gemmecker
Bayerisches NMR-Zentrum
Dept. Chemie, TU München
Lichtenbergstr. 4
D-85747 Garching
Germany
Raum/Room 2108 / BNMRZ, E.O.Fischer-Str. 2
Tel. +49 (89) 289-52604
Fax +49 (89) 289-52669
e-mail: Gerd.Gemmecker_at_ch.tum.de
Internet: http://www.gemmecker.de
Received on Fri Jul 06 2018 - 02:24:13 MST