Pure Ether as fuel... Dangerous?

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.
redchigh
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Thu Sep 13, 2007 3:19 pm

Okay- I think I know how to seperate Ether from Starter Fluid, and put it in a pump spray bottle.
The starter fluid is propelled by CO2 and I think aerosol is screwy (to measure). Would it be Suicide to use it in a cannon?
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thespeedycicada
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Thu Sep 13, 2007 3:30 pm

no ive tried pure ether from my dads work (the chemists there will give us nearly anything) and it worked great! no explosion or anything.
iknowmy3tables
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Thu Sep 13, 2007 3:38 pm

fuel air ratios render almost all well constructed combustion spud guns safe for most fuels only if some people could fricken understand that
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paaiyan
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Thu Sep 13, 2007 4:08 pm

iknowmy3tables wrote:fuel air ratios render almost all well constructed combustion spud guns safe for most fuels only if some people could fricken understand that
Dude you lost me at "only if." Can you try that one again?
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Hubb
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Thu Sep 13, 2007 4:24 pm

paaiyan wrote:
iknowmy3tables wrote:fuel air ratios render almost all well constructed combustion spud guns safe for most fuels only if some people could fricken understand that
Dude you lost me at "only if." Can you try that one again?
He said it is safe to use ether.
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paaiyan
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Thu Sep 13, 2007 4:25 pm

hubb017 wrote:
paaiyan wrote:
iknowmy3tables wrote:fuel air ratios render almost all well constructed combustion spud guns safe for most fuels only if some people could fricken understand that
Dude you lost me at "only if." Can you try that one again?
He said it is safe to use ether.
Well i caught that much, he just lost me after that.
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veginator
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Thu Sep 13, 2007 5:40 pm

iknowmy3tables wrote:fuel air ratios render almost all well constructed combustion spud guns safe for most fuels only if some people could fricken understand that
He meant it like this.
Fuel air ratios render almost all well constructed combustion spud guns safe for most fuels. Only if some people could fricken understand that.
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meatballs
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Thu Sep 13, 2007 6:10 pm

there is only a fixed amount of oxygen in a chamber to begin with, which limits how much fuel can be oxidized regardless of how much is present. this means that only a certain amount of energy can be released from fuel mixed with air in the chamber. the only time it gets real dangerous is when you mess with the oxygen levels in the chamber, either by compressing the fuel air mixture or by just adding oxygen at atmospheric pressure. so you're fine with ether.
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dongfang
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Thu Sep 13, 2007 7:05 pm

Hi,

I also hold the view that just about any fuel in atmospheric air is safe in a well constructed and well maintained spud gun. There is not so much of a difference between fuels, as long as they burn in air.

I have tried with: Deodorant, ethanol (never got that to ignite, but it might have been too cold), propane and acetylene. In my large (5m barrel!) combustion gun, propane would go up to 250 m/s and acetylene up to 275 or so - not much more energy, despite warnings about the power of the stuff. (I had to use 40% oxygen with butane to get Mach 1.13, now that made a difference). Even hydrogen is not as powerful as it might appear, because one will need so much of it that quite a lot of air gets displaced.

"Burnt Latke" (burntlatke.com) compared starter fluid with butane in his famous measurement series. It came out slightly inferior to butane. Pure ether would be better, but still without nasty surprises.

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Soren
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Hubb
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Thu Sep 13, 2007 7:09 pm

Just curious, what is your method of extracting ether from the starter fluid? If you hold the can up-side-down to expel all of the propellant, you still have starter fluid. Share with us your method, please.
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Thu Sep 13, 2007 7:43 pm

sorry about the confusion I'm still annoyed with abc news and there crappy report on spudguns, as well as other people who render combustion spudguns unsafe, and acually belive that
According to Division Chief Jim Sideras, "The problem can be if something gets plugged up, too much propellant, it will actually explode."
Blackett
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Thu Sep 13, 2007 7:44 pm

Paay said it came form a chem lab (his anyways) so I'm assuming it just comes liek that.

i don't know about isolation form other components in starter fluid though.
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meatballs
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Thu Sep 13, 2007 9:39 pm

Dogfang: the difference between say propan, and fuels like acetylene, or especially hydrogen, is the burn speed. they dont necesarily contain more energy, but they burn much more quickly creating a more intense pressure spike. that is why they are so much more dangerous. so i wouldn't agree that just about any fuel is safe, but with something like propane, butane, aerosols, and ether, that doesn't detonate the way hydrogen does, you're safe so long as no additional oxygen is used.
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Fri Sep 14, 2007 1:23 pm

Even with hydrogen as long as the oxidizer is just air at 1 ATM the chances of a problem are pretty slim. Yes, hydrogen burns a lot faster but not fast enough to really be a problem.



Separating the ether from the CO2 carrier is not all that hard to do. Just spray the stuff on a cold surface. Ether is pretty low boiling (~95F IIRC) but it will still condense on a cold surface. Heck, you could just spray the can into a baggy immersed in ice water. Not terribly efficient but if you are using starter spray as a source of ether then efficiency is obviously not a big concern.

CO2 will not condense on any cold surface you can generate at home.

If you happen to condense water with the ether (easy to do if it is humid), then the water will be the lower layer.
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dongfang
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Sun Sep 16, 2007 4:18 am

Hi,

I´ll have to make an experiment to provoke DDT once, and see what I get. Could try to blow up my old barrel pipe or something...

Regards
Soren
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