As a sort of cautionary counterpoint to the anecdote in my How to Tell a True Lab Story post, Derek Lowe has the story of somebody who pulled the same trick with a big commercial liquid nitrogen tank:
The cylinder had been standing at one end of a ~20' x 40' laboratory on the second floor of the chemistry building. It was on a tile covered 4-6" thick concrete floor, directly over a reinforced concrete beam. The explosion blew all of the tile off of the floor for a 5' radius around the tank turning the tile into quarter sized pieces of shrapnel that embedded themselves in the walls and doors of the lab. The blast cracked the floor but due to the presence of the supporting beam, which shattered, the floor held. Since the floor held the force of the explosion was directed upward and propelled the cylinder, sans bottom, through the concrete ceiling of the lab into the mechanical room above. It struck two 3 inch water mains and drove them and the electrical wiring above them into the concrete roof of the building, cracking it. The cylinder came to rest on the third floor leaving a neat 20" diameter hole in its wake. The entrance door and wall of the lab were blown out into the hallway, all of the remaining walls of the lab were blown 4-8" off of their foundations. All of the windows, save one that was open, were blown out into the courtyard.
One of the big liquid nitrogen tanks on our loading dock has a pressure relief valve that pops with a noise like a minor explosion. It releases every half-hour or so, and scares the crap out of me every time it goes. This story is a nice reminder of why it's there in the first place...
I got once a call in the middle of the night from our security company about a terrible racket coming from the inorganics lab in our building. I drove over to investigate, but when I got there everything was quiet. As I was in the process of cursing out (to myself) the moronic security folks who'd gotten me up at 2 in the morning, the pressure relief valve on the big argon tank we had for the ICP went off, scaring the everliving crap out of me. We've since relocated the tank to a screened area outdoors.
The worst liquid N2 accident I ever heard of was an explosion at URI that took the arm off a grad student about 15 years ago.
Ooh, I missed your earlier post when it came out, but I'm pretty sure the tale of the LN2 and the sink refers to J--n S----------r, who was in the same group as I was. He did have a tendency to break things. The remains of the sink were quite a sight. Lessee, that would have been the area of 1990-1992, so no digital cameras, alas.
I hadn't heard the "That's part of the experiment" response of his (=my) advisor, but that sounds just like something he would say.
I was told a story about a bunch of guys (not chemists) in a lab who dumped a truckload of potassium into a water basin. The whole water, tens of cubic meters of it, reacted with potassium, leaving the basin virtually empty. It was a mighty big bang.
Cant seem to post an image, but heres a link to my one:
This one's more in the "silent but deadly" category: At one of the labs in my undergrad department, the students and other researchers often left the lab with headaches, fatigue, and a general sense of irritability, all of which improved slowly while they were home. After a lot of complaints over several weeks, the problem was traced to a slow leak from a CO tank. They removed the tank, and bingo: No more sick lab members.