# POW!



## Robert LaLonde (Apr 2, 2018)

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.


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## Z2V (Apr 2, 2018)

Good to hear that it wasn’t worse, darn sure could have been. What ignited the gas?


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## kev74 (Apr 2, 2018)

Wow! That was close!

I've been hesitant in bringing bottled gas into my home shop. Your experience isn't helping.


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## RJSakowski (Apr 2, 2018)

Acetylene gas at more than 14psi is unstable.  In the tank, it is dissolved in acetone which allows it to be safely pressurized. There probably was a small amount of undissolved gas at the valve and the friction in opening the valve caused the explosion and subsequent ignition. Normally, a regulator would have been in place and the explosion would have been fed through the regulator and hose but with very li5t5tle oxygen available it would have flamed out.

Even an empty tank will build up pressure if left to sit for some time as residual acetylene will come out of solution.  Always treat it with the respect it demands.

I'll have to keep this post in mind as I have an acetylene tank that hasn't been used for more than thirty years.  I thinlk that I will tie a note to the tank so I don't foget.


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## Robert LaLonde (Apr 2, 2018)

The gas had been coming out for a couple seconds when it detonated.  I do not thing it was valve friction, but I guess that is a possibility. 

From what I read acetylene is stable upto 15PSI and a volume of it at 27-28 PSI is definitely unstable.  A volume of 1 cubic foot or more of free gas is also considered unstable. 

Interestingly acetylene does not cool when it expands.  It gets warmer from what I read.

My working bottle always has a regulator on it, and is chained in place in my rolling cart along with my oxygen bottle.


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## Eddyde (Apr 2, 2018)

Glad to hear it wasn't too bad.
Aside from 1lb "blowtorch" tanks, I never keep Acetylene or any flammable gas tanks in the house/shop. Way too risky IMHO and illegal in some places. I keep em outside and simply run the hose in when I need to use and put it back when I'm done.


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## Tim9 (Apr 2, 2018)

Thanks for posting this. I have read warnings before....But your explanation totally clarifies it for me. The key is to always have a regulator hooked up. Man that must have been scary as crap.


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## Robert LaLonde (Apr 2, 2018)

Adrenaline kicked in almost instantly.  Haven't dealt with any real emergencies in a few years, and I wasn't sure I would still react like I used to.  At 52 I am slowing down a little.  I felt like I was thinking at normal speed, but my body and everything around me was in slow motion.  I was considering options as I moved.  I had already dismissed the water hose a few feet away as I trotted past it.  15 minutes later I felt shaky as all heck on the inside, but my hands were steady on the outside.  

Fearing severe burns on my dad's hand I was queasy an hour later as we sat in the ER waiting to see what the doc said.  His hand was grey.  Instant acetylene soot tattoo I guess.  LOL.


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## BtoVin83 (Apr 2, 2018)

When I was a kid we had a bottle of hydrogen laying in the driveway next to the curb, dad used to fill balloons once in a while for us kids. He would pop them with his cigar, he thought that was pretty funny.


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## HMF (Apr 3, 2018)

Thanks for posting this. We need to make this part of the safety forum. If we can save someone injury, that would be wonderful.


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## MAKEITOUTOFWOOD (Apr 3, 2018)

Scary! Glad no one was seriously hurt.


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## cg285 (Apr 4, 2018)

hmmm, i just swapped out several bottles of oxy and act monday. the guy at airgas opened the valves on all the tanks before he handed them to me. never saw that done before.


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## Firestopper (Apr 4, 2018)

Was the bottle/cylinder stored upright prior to opening valve?


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## Robert LaLonde (Apr 4, 2018)

firestopper said:


> Was the bottle/cylinder stored upright prior to opening valve?


Its been standing upright in the exact same location for years.


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