Why not to use acetylene as spud gun fuel.

Boom! The classic potato gun harnesses the combustion of flammable vapor. Show us your combustion spud gun and discuss fuels, ratios, safety, ignition systems, tools, and more.
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Extrusion
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Tue Oct 10, 2006 2:32 pm

*sigh* ok acetylene expands (or produces expanding hot gasses.) to fast for the potato to leave the barrel the pipe just explodes because when the acetylene detonates it build up the pressure to fast and the pipe just goes boom i cant really type it out youll need someone like BLB (boiling lead bath) to explain it to you he is smart and as for your friend doing it in practicly unrated pipe i think thats B.S. (No offence i dont want to cause problems.) i will attepmt to find a video of propane combusting and if i cant some time later today or tommarow when i have more time i will do a bag of propane and video tape it.

Note: im not saying it cant be done at all because it can and has been done in metal cannons anyone who would attempt it in PVC is just stupid.
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Extrusion
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Tue Oct 10, 2006 2:44 pm

Sorry about the double post but i found this video on youtube look at the difference of this explosion with a propane ballon and the acetylene bag one if acetylene had been in the ballon on this one that guy woud probably have gotten hurt.


Another one of propane:
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zeigs spud
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Tue Oct 10, 2006 4:26 pm

wow..when i first saa this thread and the video i didn't see why not to use it, but not being a big combustion cannoner i left it at that. now looking at the propane vid i see lol that it would just blow you and your cannon to itty bitty bitz lol. The propane isn't so much of an "explosion" as a quick phase change to a plasma (fire) to quickly fill the combustion chamber. I Knew this already but it was a good re-fresher/clarifyer lol.
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Extrusion
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Tue Oct 10, 2006 5:20 pm

Hopefully no one will ever think of using acetylene in a PVC cannon and even if its in metal one it is still dangerous and the other dude says his friend used acetylene in "practicly unrated pipe" thats total B.S. it would rip it to shreds lol.
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zeigs spud
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Tue Oct 10, 2006 6:09 pm

that or it was a 4uk!n miricle he is still alive. lol yea o hope no one ever atemps this.
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ProfessorAmadeus
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Tue Oct 10, 2006 8:14 pm

here you go
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joannaardway
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Wed Oct 11, 2006 4:53 am

Rule 1 when talking to me - never start a post with *sigh*. The negative effects aren't worth it.

Hell, I'll link you to the topic for the cannon on UKSGC:

Combustion cannon

That has been used with acetylene, without any deaths. I'll make sure he's made aware of your opinions of his spudding stories.

But, simply, as I said, most of the "horror" stories are urban legends.

One of the famous ones has a kid seeing a friends cannon, building his own, using his dad's oxy-actylene rig, and blowing out all the windows in his house. He allegedly survived, after having pvc shards extracted.

This is either a total lie, or grossly over exaggerated. Based on the amount of fuel, it is not possible to blast out all the windows in a house from the basement - that couldn't be achieved even with Nitrogylcerine.

Ok, let's say he does blow out the windows. To blast out the windows, the force of the blast would have been so excessive that there is no way in hell he could have survived.

The facts don't fit.

And you can't yet assume anything from the videos - that could easily have been oxy-acetylene in the first video (most people don't differentiate).

I can accept that acetylene is dangerous - easy. I wouldn't use it.

But, regardless - Acetylene is seriously overhyped.
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FreakyShotGlass
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Wed Oct 11, 2006 5:14 am

According to that site the cannon you linked to is powered by butane.
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joannaardway
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Wed Oct 11, 2006 6:35 am

It's usually used with butane, but it has been powered by acetylene.

topic that states use of acetylene

Posts 30 and 35 are of most interest to you.

And yes, we are quite silly on UKSGC - no commenting about it.
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sgort87
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Wed Oct 11, 2006 9:55 am

Hey! Nice to see you on here Jo. I guess you got a little bored of Spudtech too eh? :P Well, welcome aboard. Very welcome.
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joannaardway
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Wed Oct 11, 2006 2:55 pm

It's good to be here.

I mostly got fed-up with the edgy forum software at spudtech.

That, and I'd been meaning to join for ages, but forgot.

Anyway, I've got loads of new ideas, which I need to do something with.

I'm off to create a topic about different combustion fuels - if I can't find an old one to use.
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Extrusion
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Wed Oct 11, 2006 3:05 pm

Ok well im not going to argue im not that type of guy i dont want any bad blood between anyone the point is dont use acetylene as a fuel if you know nothing about it now some people do exagirate about the power of acetylene blasts have the time ive ever played with it i was either drunk or on something else and well when your drunk the next morning you remember next to nothing but i do know the crap is dangerouse in a confined area and isnt safe to use in a spudgun bye no means (not saying it cant.).
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critical_al
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Sun Oct 15, 2006 3:34 pm

Some years ago when younger and dafter I built a number of cannons, running off various propellants, culminating in an oxy-acetylene powered cannon. It was constructed out of heavy guage steel tubing, welded properly, with a sparkplug ignition system so I could fire it from a (safe) distance. It would fire frozen oranges more or less out of sight, and cause serious damage to anything in the way. While this was pretty cool at the time it was also very definately not a toy.

As a number of people have said, it's not dangerous to build an oxy-acetylene or similar, IF YOU KNOW WHAT YOU ARE DOING!
With a bit of fancy maths its relatively simple to work out, for a given volume combustion chamber, how thick the metal needs to be as long as its welded properly. Even with a suitable safety factor you might be suprised how thin it needs to be to contain the detonation. Of course if you are not too confident with your maths you could just make it twice as thick and then add a bit for luck :)

If all this seems a bit technical then you should probably stick to propane etc!
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pyromanic13
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Sun Oct 15, 2006 4:03 pm

this doesn't scream don't use oxy-ace to me, and I've seem the effects (accidently blew up a metal trash can with the lid just SITTING on top)
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reaper613
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Sun Oct 15, 2006 4:08 pm

has everyone just chickened out and called it quits on building bigger and better cannons, is there no one out there who will challange my oxy-ace gun with one of their own. enough with all the "dont use acetylene topics" man up and build somthing far batter than these hairspray cannons
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