Mixing Oxyacetylene in the same cylinder

[onetreeforge]

I am not sure if this has been posted but this guy not far from me was mixing up LPG cylinders full of oxyacetylene and selling them, he was trying to use one to heat some exhaust tube when it exploded, he was renting my friends mother in laws house, the description I got of the situation was hideous.      

https://www.nzherald.co.nz/nz/news/article.cfm?c_id=1&objectid=12119555

[DuEulear]

Heck acetalene under pressure in a tank without oxygen is a shock sensitive explosive. That is why acetalene tanks have the pumice and acitone in them to stabilize it for transport. Which is also why we dont tip tanks for transport or draw too much volume too fast from a acetalyne tank

putting both in the same bottle under pressure is suicide. 

I hope he did not manage any sales before he went boom

 

du

[JHCC]

Just reading the headline, I knew this was going to end badly.

[Guest]

One Word Darwin ! & one less Gee

[Cincinnatus]

There is a reason oxyacetylene are in separate tanks, flash arrestors, and all the special fittings - when someone says they have modified high pressure tanks - run....

[Daswulf]

Sad really. Ignorance can kill. His friends "I'm Out of here" senses saved his life. 

If you ever get that sense, Listen to it. Try to get the person to stop messing with whatever it is too. 

One sad example why IFI pushes safety so much. 

[MC Hammer]

I once spoke to a missionary who lived in Jerusalem and asked her how she kept safe there.  She said she listens to that still small voice that tells her when something is wrong.  She said that when she's home in America she's noticed we don't listen at all or very little to that voice because we live in such relative safety.  She said often times our mind perceives things that are out of place or not right and will signal that fear or small voice that says something is off.  I've always remembered that conversation when climbing around on ladders or handling things with gas hooked up to them,  handling firearms, etc.  There's a book out there entitled "The Gift of Fear" that's pretty insightful on listening to that little voice telling you to run or that something isn't right or safe.   

[Anachronist58]

The RED stripe on the acetylene gauge that starts at 15 psi is not a joke. Confined acetylene in the hose is Explosive above that pressure.

[Cincinnatus]

1 hour ago, MC Hammer said:

.......  There's a book out there entitled "The Gift of Fear" that's pretty insightful on listening to that little voice telling you to run or that something isn't right or safe.   

My wife spent a year deployed to Kabul, Afghanistan - in her training they gave her that book - "the Gift Of Fear" and taught just that - trust that voice that if something doesn't feel right - it probably isn't..

 

[ThomasPowers]

Whenever you come up with a "simple, easy, cheap" way to improve a process that nobody else is using; there should be a loud voice in your head saying "DANGER  Will Robinson DANGER WARNING WARNING". And you should check with other people *why* things are not done that way. I'd think that any welder would know the danger and thousands of folks here could have warned him off.

The internet encourages people to think that their ideas don't need vetting by experienced people.  Tragically this can be a fatal example of hubris.

Thank you for posting this classic example of "making a fuel air explosive".

[MotoMike]

so sad.  in this day and age of information, a little research would have gone a long way.  

[Frosty]

Reading the article that wasn't written by someone who understands acetylene told me all I needed. No, it wasn't a spark when he tried to use the torch. No worries he didn't "sell" a premixed tank of oxy acet. Acetylene C2 H2 is very unstable all by itself it will spontaneously decompose with little help, as said. room temp pressures higher than about 2 atmospheres IIRC, the red line on the acet gauge has a safety factor, AT ROOM TEMPERATURE! 

Add shock or the wrong metallic catalyst and it will spontaneously decompose at a much lower temp, say 16-17 psi? 

Judging by the testimony of the survivor who listened to the voice and got out of dodge. The victim was goobering a rig to pump oxy and acet into a propane bottle. By what little I really KNOW it never got full enough to register on a gauge. By spontaneously decompose the atoms in the molecule break apart releasing lots of heat, it can't burn, there's no oxygen in that reaction. However there is plenty of energy to burst the container and there's oxygen outside so you can get a second, a fuel air, explosion.

However, pump acetylene above decomp psi in the presence of oxy and it will burn with a propogation rate of approx 24,500 fps. that's well above orbital velocity. Hmmmmm? Shrapnel was blown THROUGH tool boxes full of tools. Hmmmm?

15 psi is considered safe in a torch set because the two are NEVER mixed at that pressure, that's the supply pressure and it's introduced into a mixing chamber in the handle through jets at a much reduced pressure.

Anyway, I believe the propane tank of mixing oxy propane detonated at maybe 10 psig. (static sparks are common with acet) and because there was so little volume in the tank he didn't take out the neighbor's houses and his friend. It must've been well out of a stoichometric range too, possibly resulting in a small % of the acet that was there exploding as oxy acet. The remainder of the unburned but super heated C1 and H1 (no, it wouldn't have been C2 & H2) gasses would've burned in air in a secondary fuel air explosion. 

Too many glib things come to mind about chlorinating the gene pool but I got too close once when I was a teen. I'd made the mistake of loaning Dad's portable torch to a friend to cut his VW bug in half to make a dune buggy his Dad's set was MT (empty). I'd pulled the pickup around and parked it out front and walked back to find him taping the hoses together to refill his Dad's dead empty acet tank! Dead empty acet tank means the acetone is depleted too. The blast would've leveled his house and maybe the one across the alley. Happily Dad's set was on a cart, I grabbed it and went straight to the pickup and loaded it.

I get chills now, if I'd had a cell phone and stopped to answer it it would've been a very different day.

When I mention Dunning Kruger it's not really a joke. I'm sure Mr. Miller wasn't stupid, he just had a "good" idea. Mr. Oneil listened to the voice and lived.

Thanks for the link, you may have just saved a few lives!

Frosty The Lucky.

[MotoMike]

It is a sad story, but dang it Frosty, I enjoyed your write up.  

 

[ThomasPowers]

"dissociates exothermically" was how my instructor put it. He did the 3 balloons demo too: 1 Balloon pure acetylene; 1 baloon pure O2, last balloon stoichometric mix:  piff, piff KABOOM!

[MC Hammer]

8 hours ago, Cincinnatus said:

My wife spent a year deployed to Kabul, Afghanistan - in her training they gave her that book

It was standard issue for the guys I used to train and lead.  It even helps with hobbies like blacksmithing.  When something you are doing feels dangerous, that little voice will say "Hey, you don't really have the right pair of tongs for this."  Listening will save you a lot of grief.  

[SLAG]

The benighted fellow inadvertently mixed up a Sprengel explosive mixture.

Herr Hermann Sprengel published his theory in the 1870's.

That is a mixture of a 'fuel' and an oxidizer.

In this case the acetylene functioned as the fuel and oxygen was the oxidizer.  (there are other oxidizers and fuels suitable for the Sprengel reaction).

The two gases were very intimately mixed.

Such a mixture could detonate due to the very slightest shock. Yehh,  a sneeze could have touched it off. (no kidding).

Indeed acetylene, itself, is highly unstable. It breaks down all by itself,  without the influence of shock or temperature change. (though either of the two will speed up such a reaction).

Acetylene in liquid form is more stable than it is in a gaseous form.

The fellow mixed the two gases together, and the system blew up.

The acetylene molecule has a highly dense source of enormous potential chemical energy. Oxy-acetylene burns at a  temperature 0f 6,020 degrees Fahrenheit.

Also, copper or brass serves as a catalyst for acetylene decomposition. A copper coupling or valve could have helped set off the blast.

Lack of some basic chemical knowledge resulted in the fellow's downfall.

SLAG.

[JHCC]

Something like this happens every time I think about getting an oxyacetylene rig. Think I'll stick with coal and MIG. 

[Daswulf]

Hah, John, stories like this bring me back to my toes on paying attention to what I'm doing with them and how I'm using them. 

I knew there were reasons I never liked them.

[Frosty]

4 hours ago, Daswulf said:

I knew there were reasons I never liked them.

Your toes? 

Might want to reread your post Das, I didn't even have to try to pick up THAT straight line.

Thank you sir. May I have another please?

The copper looking alloy on torch sets is a bronze alloy that won't act as a catalyst or form explosive compounds. 

Frosty The Lucky.

[Glenn]

And DO NOT use any grease, oil, etc on the tanks, gauges, hoses, etc on OX/AC rigs. Boom is not a nice noise.

[DuEulear]

Jhcc

 

They are perfectly safe if used and matained correctley. And very useful when you need localised heat quick.

writing off the use of a tool because it is dangerous if used improperly pretty much excludes you from this hoby as all our tools will hurt you if you do not understand and mittigate the risks.

 

du

[Daswulf]

Eh, yeah frosty, I have my moments of making zero sense. Was talking about oxy/acetylene torches in response to Johns comment.