Liquid nitrogen calamities

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Via @sarahdcady on Twitter, some liquid nitrogen stories from 2006. One wasn’t quite a calamity–but it easily could have been.

Down the stairs at the University of California, Berkeley:

Yesterday the LeConte elevator was out of order, which for most of us would have meant taking the long way around. However, one undergrad, tasked with transporting a full 230 L dewar, simply decided to take the stairs.

At about 80% the density of water, 230 liters of liquid nitrogen weighs about 400 pounds, not counting the additional weight of the steel vessel containing it. When rolled onto the stairs, the dewar promptly tipped over and plummeted downward on its side, knocking deep gouges in the marble steps and dragging along the unfortunate student, who inexplicably held on as his cargo began to tumble. Miraculously both student and dewar arrived at the landing without rupturing, but the dewar was still on its side and pressure was building up.

This was the situation when we got the frantic call from the building manager; once enough of us arrived at the scene we were able to pull the dewar upright and release the pressure. This averted any imminent explosion, but now we had a different problem: 400 pounds of liquid nitrogen stranded on a landing between the ground and first floors. Suggestions were floated including emptying the nitrogen out the nearby window, but ultimately we found another dewar which was wheeled to the top of the stairs on the first floor, and the nitrogen was transferred there through a long hose. The empty dewar was then carried up the stairs, a task requiring four men and gouging new (but shallower) grooves in the staircase.

When metal plugs replaced pressure relief and rupture disks at Texas A&M University:

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.

@sarahdcady managed to dig up photos here.

Author: Jyllian Kemsley

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