Acetylene Cylinder
A few years ago I was changing acetylene cylinders on a welding set (the big industrial 5 foot tall ones). Dragged the new one over and stood it next to the old one, unchained the empty cylinder and dragged it out knocking over the full one in the process. (golden rule with high pressure cylinders is don't leave them standing up unsecured).
As it hit the floor the valve snapped off and the cylinder took off horizontally like a Saturn 5 rocket, punched holes through TWO breezeblock walls into a neighbouring industrial unit and ended up spinning round and round in their workshop venting highly inflammable acetylene everywhere as everyone ran for cover.
Fire brigade where not impressed when they were called out to make sure it was safe.
(Alf N. Safety - refusing you planning permission on, Thu 20 Dec 2007, 15:13, closed)

Horizontally like a Saturn V?
Shurely shome mishtake?
( Enzyme is in ur [noun]z, [verb]in' ur [noun]z, Thu 20 Dec 2007, 15:20, closed)

You're right
Surely it should be Ariane 5?
( rubberduck should only be used after consulting with your GP, Thu 20 Dec 2007, 15:22, closed)

...
Lol!
( Enzyme is in ur [noun]z, [verb]in' ur [noun]z, Thu 20 Dec 2007, 15:25, closed)

I was changing nitrogen bottles
in our gas service room one day, with the assistance of a (very slightly built) student. I asked her to move a full one so I could get the empty one in its place. She didn't realise how heavy they were and the full cylinder topped, knocking her over to her injury, and fell on the floor with a huge clang. I nearly shat myself.

Fortunately the neck didn't break, or obviously I wouldn't be here to write this, but I now no longer employ small female students as manual labour!

Especially as I had to take her to A&E to have her head repaired.
( K2k6 has been using boiling nitric acid, Thu 20 Dec 2007, 16:00, closed)

Lucky old you
Thanks your stars you didn't knock over the oxygen one. Much higher pressure ...
(ubergeekian, Thu 20 Dec 2007, 16:10, closed)