Best Mix For oxygen+acetylene devices (for a friend)

[green beret]

I did a search on this but came up with nothing, although I swear there was one.

Anyhow, a friend of mine had a dream that he found this place where there were full cylinders of oxygen and acetylene (also LOTS of empty ones) left out side ungaurded and unlocked 24hrs a day 7 days a week. He dreamed he was going to get some.

He wanted to know what the best oxygen to acetylene ratio was for producing the loudest possible bang, in garbage bags and balloons and any other things that can be used.

He thought that a good one would be roughly 70% oxygen and 30% acetylene, but wasnt sure. He was also unsure how to measure this ratio, by looking at the bag/balloon he supposed.

He would also appreciate it if you could give other info such as, simple and safe ignition, the distance that would be safest to avoid death and burst eardrums, because in his dream he wanted to have fun this new year. I told him to use a 30-40sec fuse with a heap of match heads on the garbage bag to ensure ignition.

He would be very grateful if you could help, and also tell him how long it takes this gas mix to disperse from a balloon or garbage bag, and if the water displacement method is the best way to fill garbage bags.

A VERY big thankyou to all who help my friend in his dream.

[vulture]

My chemistry book describes an experiment in which they fill a metal canister with acetylene and air, the close the canister with a cork and ignite the mixture.
There goes a security advice along with it which says everyone has to open his/her mouth to avoid ear damage.

They use 1/10 acetylene and 9/10 air.
But air only contains 21% oxygen and because your friend got pure, the ratio should be adjusted to use more acetylene.

Here's the reaction:
2C2H2 + 5O2 -> 4CO2 + 2H2O

So logically, IIRC, you should use a ratio of 2 units acetylene to 5 units of oxygen.

However, you should take in to account that there will slip in some air into the mixture, unless you've got equipment to fill it.

[This message has been edited by vulture (edited 11-19-2001).]

[Anthony]

Just watch out for static discharge.

I recall Philou once saying that acetylene/air mixtures were capable of detonation at approx (IIRC) 3500m/s and that a garbage bag of the mix could demolish a brick wall. Haven't verified it myself but the guy knows his stuff.

[ALENGOSVIG1]

Just steal a large cylinder and attach a large charge to the side.the acetylene will actually detonate.

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[CodeMason]

<font face="Verdana, Arial" size="2">So logically, IIRC, you should use a ratio of 2 units acetylene to 5 units of oxygen.</font>Because O₂ is a smaller molecule than HC<u>=</u>CH, and they have different densities, by volume, one part of oxygen and one part of acetylene will not contain the same amount of molecules.

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[mrloud]

If you can get oxy-acetylene cutting torch then you can light it, adjust the ratio until you get the hottest blue flame possible. You should now have the two gasses flowing in the optimum ratio. Snuff the flame out on something and fill up your garbage bag/weather balloon etc.

For an igniter you can use the magnesium wool out of a disposable camera flash bulb. You could stuff the wool into a short section of drinking straw and secure a wire in each end. Simply connect it to a power supply for ignition. A nine volt battery has worked for me but if you are using long wires (hopefully) you might need a bit more grunt.

Anthony is right, a bit of static and you a goner. I would fill the bag/balloon using a long hose. That way, you never need to be anywhere near the large amount of gaseous mayhem.

Another thing just occured to me. It'd be a good idea to plan a method for safely deflating the bag in the event the igniter does not work.

As for safe distances: just wear earmuffs and start off small. A balloon the size of a baseball made me jump of my seat in a lecture theatre. A garbage bag full is a frightning prospect.

[nbk2000]

Spray the bag inside and out with an anti-static spray used for keeping clothes from clinging.

If you have a pond or stream nearby, you could fill it in the water and let it drift off to go boom. Water eliminates static hazard.

Acetylene has a large combustion range so it'd be difficult for you to make it too lean or rich to burn.

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[vulture]

according to gas theory:
pxV = nxRxT

so logically n = pxV/8,31xT

(n = mole quantity, V = volume, T = temperature, R= constant value = 8,31)

The temperature is the same so you'd only have to know the partial pressure.

Anybody help me out on this cause i'm not sure if it's correct...

[shooter3]

Just to awaken your caution; A guy was working on a new constrution job, doing some welding. The reverseflow check valve on the torch head got jammed and the oxegen flowed into the acetylene tank. They don't know if it was spontainiuos, or he was lighting it, but the tank went off and killed him. It also took down a large part of the building. Work your charges up. Don't start with trash bags untill you get a feel for what you are doing. Have fun.

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[Anthony]

How do you snuff out a flame that has it's own oxygen supply?http://theforum.virtualave.net/ubb/smilies/smile.gif

If the ignitor doesn't work just get the flaming-rag-on-a-stick to finish it off.

[mark]

A fun thing to do with acetylene is the old "can cannon" trck. You get a pringles can and make a 1/16" hole in the top and bottom of the can. Plug the hole on the metal part and fill the can completley with acetylene. Rest the can on something ventelated with the metal side facing up and remove the tape from the hole. Ignite the gas with an electric igniter. A lantern flame will apaer on the top of the can for a minite or so before exploding thunderously.

Oh, and for acetlyne and air, my old friend James told me that a mixture of 10psi acetlyne with 5psi oxygen. Or was it the other way around?

[This message has been edited by mark (edited 11-20-2001).]

[nbk2000]

You hold the tip of the torch against the (assuming) concrete floor. It snuffs out the flame. Don't know why, it just does.

A BB gun to perforate the bags would disarm them if they don't ignite. You could have a reallly long string tied to the bag and pull them onto a road flare. THAT'LL light it!

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"I have begun evil, I shall end evil. That is the end that awaits me."

Go here (http://briefcase.yahoo.com/nbk2ooo) to download the NBK2000 files and videos.

[BoB-]

What about plastic bottles? You could use 3-liter, and 1 gallon PET bottles for the charges, also easier to intall an ignitor (in the cap).

You might want to consider that if there were a leak, holding a flame to fuse wouldnt end up good for you.

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[nbk2000]

Acetylene is very forgiving as regards ignitable ratios. Mixtures with air containing more than 3% or less than 65% acetylene gas are explosive, the maximum explosive ratio being 1 vol gas and 12.5 vol air.

To get the ideal explosive ratio, place a plastic 5 gallon bag in a 2 liter soda bottle that's had the round top cut off. Make sure the bag is squeezed flat and free of air.

Fill the bag with acetylene till it fills the 2 liter bottle.

Remove the bag from the bottle and continue to fill bag with air till full.

You now have a bag with the most explosive mix of acetylene and air.

For oxygen instead of air, use a gallon bottle instead of the 2 liter, and fill the bag 2/3 full with oxygen instead of air. To make it easier to estimate the 2/3, place the bag in a plastic milk crate and fill till the bag fills the crate halfways.

Don't bubble acetylene through water since it dissolves 1 to 1 per volume

Since these ballons are about the same weight as air, they'll float quite easily with a regular helium ballon or two attached. Attach the ballons, light your fuse, and let it drift up to air burst.

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"I have begun evil, I shall end evil. That is the end that awaits me."

Go here (http://briefcase.yahoo.com/nbk2ooo) to download the NBK2000 files and videos.