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heptane

Post questions and info about combustion (flammable vapor) powered cannons here. This includes discussion about fuels, ratios, ignition systems, safety, and anything else relevant.
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heptane

Unread postAuthor: lukemc » Fri Apr 13, 2007 9:03 am

my mom was out shopping and and i realized i was out of spray deoderant so i called her and asked to pick some up as long as in the ingredients it had propane or butane. she comes back with this
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the ingredients go SD alcohol,Heptane, Propane, Butane, Propylene Glycol, Isobutane, Fragrance, triclosan.

i saw the propane and butant and thought ok this might work then i saw the heptane and had never seen this before and i might be ok.

i shoot it and it shreds a potato inside my barrel and shoots potato chuncks out and put me a few steps back. this potatos that was shreded is from the same bag that had been shooting before with axe.

next i shot a chunk of wax 100+ yards. (measured by google satalite by landmarks.) i had to have my 6'1 friend help me with this shot.
i concluded that this must be the heptane that did this so i looked it up on wikipedia http://en.wikipedia.org/wiki/Heptane if you can make any sense of this page tell me or if you see a different ingredient that could have done this please tell
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Unread postAuthor: mark.f » Fri Apr 13, 2007 9:10 am

"Heptane (also known as dipropyl methane, gettysolve-C or heptyl hydride) is an alkane with the chemical formula H<sub>3</sub>C(CH<sub>2</sub>)<sub>5</sub>CH<sub>3</sub>."

"The straight-chain isomer n-heptane is the zero point of the octane rating scale. It is undesirable in petrol, as it burns explosively, causing engine knocking, as opposed to branched-chain octane isomers, which burn more slowly and give better performance."

~ Wikipedia

There's the article pretty much boiled down for ya. The rest is a big list of isomers of heptane.
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Unread postAuthor: lukemc » Fri Apr 13, 2007 9:15 am

"The straight-chain isomer n-heptane is the zero point of the octane rating scale. It is undesirable in petrol, as it burns explosively, causing engine knocking, as opposed to branched-chain octane isomers, which burn more slowly and give better performance."

~ Wikipedia


i think i stumbled on something good
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Unread postAuthor: jackssmirkingrevenge » Fri Apr 13, 2007 9:18 am

I have access to thousands of litres of the stuff at work :D
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Unread postAuthor: jimmy101 » Fri Apr 13, 2007 10:04 am

Don't know where the <a href="http://en.wikipedia.org/wiki/Heptane">Wiki</a> writer came up with "Heptane (also known as dipropyl methane, gettysolve-C or heptyl hydride) is an alkane with the chemical formula H3C(CH2)5CH3." Heck, he goes on to say "heptane" is synonymous with "n-heptane" which is not "dipropyl methane,...", it is just CH3CH2CH2CH2CH2CH2CH3.

Heptane appears to be one of the few hydrocarbon fuels that will, relatively easily, do a deflagration to detonation transistion.

I don't think a spud gun generates nearly enough pressure to actually get heptane to detonate. It'll detonate in a car engine at compression ratios above 8:1 or so but that is a pressure of what, 120 PSIA?

Hard to imagine a combustion spud gun getting anywhere near that much pressure. It would be very interesting if heptane does actually detonate in a spud gun.

How are you fueling this gun? I assume it is squirt-and-screw (spray-and-pray). What are the guns dimensions?

The energy content of the various hydrocarbons, the alcohol, etc. in this mixture is really not all that different from pure propane. I wouldn't really expect it to be any better, and probably a bit worse, then propane.

More info please.
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Unread postAuthor: lukemc » Fri Apr 13, 2007 10:20 am

ok well it is a spray and pray with and 3" chamber and 2" barrel and chamber fan pezio electric ignitor and has a perfect 1:1 ratio
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Unread postAuthor: SpudBlaster15 » Fri Apr 13, 2007 1:08 pm

From GasEQ:

Propane:

Adiabatic flame temperature: 4292*F

Expansion: 137PSIG


Heptane:

Adiabatic flame temperature: 4308*F

Expansion: 140PSIG


Practically identical if you ask me.
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