Here is a photograph illustrating a most effective technique to break an NMR sample tube at the top of the upper barrel, thus potentially (1) contaminating the probe, (2) putting the spectrometer out of commission for an extended length of time, (3) causing several thousands of dollars worth of repair costs, (4) incurring the wrath of the NMR user community, and ultimately (5) losing your own access to the NMR Facility.
Here is a "photo" (what word do we use these days?) from the University of Illinois, Urbana–Champaign, of a partially quenched horizontal magnet holding onto a gas cylinder and cart.
Due to a short-circuit in the MRI console of a Freiburg hospital (August 2001), heavy smoke penetrated into the adjacent rooms. Unfortunately the well-trained and competent staff was asked to leave the area, and so nobody knew that in spite of turning off all power supply the magnet was still energized. During a check-up round a fireman with full breathing equipment was drawn into the bore where he got stuck. Only after quenching the magnet could he be saved, suffering serious injuries. (See "Brandschutz" Deutsche Feuerwehr-Zeitung 3/2002 p. 281 ff.) As a consequence the fire department told us to establish a fixed stoppage around all magnets greater than 10 Tesla at the campus.
Due to cost reasons, the liquid nitrogen is produced at some universities by small liquifier machines. The quality with respect to oxygen content of this nitrogen varies between 0.1 and 5%, of course, dependent on liquifier performance and operator skill. Whereas this is probably not important for everyday laboratory use, the consumption of this type of nitrogen in long-hold dewars, e.g. NMR magnets, may pose a problem. Mass spectrometric analysis of the content in seven magnets at our place, which were without uninterruption filled by this type of nitrogen since years, indicated last week a nitrogen:oxygen ratio approaching 1:1 (!). We are currently debating on the most efficient and safe way to remove the problem.