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Hairspray V butane

Posted: Tue Dec 21, 2010 7:15 pm
by cfb_rolley
So recently, my local store started stocking butane lighter refill cans, and a while ago I saw a small combustion rifle that used the bottom of a lighter as a fill port to utilize butane refill cans as fuel.

I'm going to go with the same idea on my current combustion, as I'm lacking funds for a propane setup. What sort of gains in terms of power can I expect out of butane over hair spray, and is it easier to achieve a good air/fuel mix?

Posted: Tue Dec 21, 2010 7:25 pm
by saefroch
Probably no easier to achieve a good mix, since it's still a spray 'n' pray. I built a spray 'n' pray a while back and found that it was no easier to fuel well with axe or a propane tank.

So far as gains in power are concerned, there will probably be no noticeable change, as most hairspray uses butane as the propellant gas, mixed with some ethanol. In theory, there will be slightly better yield from the butane, since it has a higher enthalpy of combustion.

IMO, the biggest advantage would be not gumming everything up with hairspray.

Posted: Tue Dec 21, 2010 7:28 pm
by jackssmirkingrevenge
Again, using a syringe to meter the correct amount of fuel is simple to do and eliminated the guesswork, why pray when you have science ;)

You can do it with a simple lighter.

Posted: Tue Dec 21, 2010 8:18 pm
by cfb_rolley
saefroch wrote:
IMO, the biggest advantage would be not gumming everything up with hairspray.
That's one of the main reasons I'm considering putting a butane fill port in. Chamber fans dislike getting sticky. It's really just a fill in budget project until I can afford to do a full build for a metered propane setup.

Posted: Wed Dec 22, 2010 6:09 am
by LovableAirGuns
use RP7 that stuff works so well

Posted: Sat Dec 25, 2010 4:36 pm
by omniscient
The vapor pressure of butane is only a little over 16psi @ 70*F, as compared to 110psi for propane, at the same temperature. Makes it kind of difficult to fuel larger combustion launchers, but may be a decent way to fuel a mini?

RP7 seems to have some pretty good ingredients, although I've never used it...

White spirit: 30-60%
Butane: 10-<30%
Propane: 10-<30%
Ethanol: 1-<10%

CLOROX Fresh Scent Disinfecting Spray has a small amount of propane (5%), but 60%-80% Ethanol. This stuff also works great for spray-and-pray.