POW!

On 4/2/2018 11:19 AM, Gunner Asch wrote: > On Mon, 2 Apr 2018 10:47:45 -0700, Bob La Londe > wrote: > >> Boy do I feel stupid. >> >> Some years back my dad brought a bunch of gas bottles over to my shop. >> Mostly owner bottles from his hardware store after he closed down. One >> was an extra large acetylene bottle I could have sworn he said was full >> at the time. Well he was over visiting yesterday, and he said it was >> empty this time around. >> >> I decided to check. Pulled off the safety cover and cracked the valve. >> >> I was just going to turn it right back off, but my dad put his hand in >> front of it just as it went POW! We both jumped, and the valve didn't >> get turned off. Flame was bouncing off the side off the corner of the >> shop and licking around the valve. I ran through my options in my head, >> and ran in the shop to grab one of my welding gloves and turned off the >> valve. >> >> We were fortunate. My dad only got first degree flash burns. The flame >> didn't melt through the metal of the shop but if it had burned much >> longer it would have. The metal is warped. Made for an exciting Easter >> afternoon. >> >> What pains me is I knew better, and the only reason I had not checked >> the bottle before is, because its a pain to go take the regulator off my >> current working bottle and walk it out there to check it the right way. >> >> >> >> > What caused the flash? I thought it took a cubic foot to flash > without an outside flame? >

There was no external ignition source. It was a spontaneous explosion at the front of the valve. My only thought was maybe my dad passing his hand through the gas flow was a secondary disturbance which cause the reaction. Maybe.

The nearest potential source and very unlikely was my electrical service entrance which was about 15 feet behind me. Nothing was being switched there so really not an ignition sources, and again the flash was right in front of the valve. I did not get flashed behind the bottle. The flash image I see in my mind might have been a cubic foot, but it was pretty small. I think much less.

The flash happened just as I was about to say, "I don't think you want to do that."

A number of years ago, the solder plug overpressure relief on one of the little thermos bottle sized acetylene blew out at a place I worked. It was on a bench in a high bay garage, away from any ignition source. I wasn't there when it blew and did not see it ignite, but it was burning like hell when I walked into the shop. It emptied in a few minutes, but it made a real impression on me. That is what motivated me to get serious about TIG welding, and later, plasma cutters for my home shop.