I went back to visit my old metalwork teacher once. It was good to see all the forge tools I`d made still hanging there on the forge. I gave a hand to some of the kids with the candlesticks they were making etc. I caught two little sctotes mucking about with the oxy acetylene bottle key. I very delicately, I thought, put it to them that I wouldn`t want to be the one to tell their parents that it was all their own fault that they got blown up/seriously burnt/damaged etc, and left them doing the brazing they were supposed to be doing with the propane torch. Only a matter of minutes later I heard the crash, so did my old teacher, and we both ran to the brick built blacksmith area at the end of the workshop. The acetylene bottle and the oxygen bottle were both flat on the floor with the oxygen bottle hissing away with escaping gas, after the gauges had broken off, and there was a strange bubbling sound along with it. My old teacher screamed "OUT!!!!!" and I rushed the kids out and away from the workshop not really sure what was happening, he went and turned the oxy bottle off before he too came out. We all hovered around, well away from the workshop, for about 5 minutes and then there was one almighty bang, followed by a purple coloured bottle exiting the far end of the workshop via the brick wall and off, like a torpedo across the playing fields. That s**t me up big time. Never seen anything like since thank god but always listening for acetylene bottles bubbling when using them.