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would this work for my spudgun?

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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would this work for my spudgun?

Unread postAuthor: spud-freak » Thu Feb 03, 2011 4:44 pm

My Question is..would this work?
thx

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Unread postAuthor: metalmeltr » Thu Feb 03, 2011 4:47 pm

Yes, you just need a precise and accurate gauge
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Unread postAuthor: jrrdw » Thu Feb 03, 2011 4:58 pm

This is a Hybird? If you posted in the wrong section let me know and I'll move this for you.
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Unread postAuthor: spud-freak » Thu Feb 03, 2011 4:58 pm

I do not have to consider the chamber? ..I mean the 8l volume.
thx

for the moment it still none a hybrid, but I would like to build one from it

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Unread postAuthor: Technician1002 » Thu Feb 03, 2011 6:12 pm

Without a burst disk, you can't meter by chamber pressure. With a burst disk, it is a hybrid even if it is a 1X. Are you sure the bottle of gas is Propane? If it is Butane you will need to adjust the mix for Butane instead of Propane.

Be sure the cap on the chamber will hold up to 100 PSI without blowing off.
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Unread postAuthor: saefroch » Thu Feb 03, 2011 7:00 pm

If you're trying to build a fuel meter for an atmospheric pressure combustion (which I think you are) you'd need both the meter volume and the chamber volume with the mix % to find the optimum meter pressure.
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Unread postAuthor: Technician1002 » Thu Feb 03, 2011 9:38 pm

I don't think he is using a meter volume. I think he is using chamber pressure rise which only works with a sealed combustion chamber thus the need for a burst disk. His pressure rise was specified as chamber pressure. He does not list a meter pipe volume or pressure. He is looking for a 0.04 bar pressure increase in the chamber if I read it right.
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Unread postAuthor: saefroch » Thu Feb 03, 2011 11:31 pm

Oh. That may be so, but the area between his ball valve and gate valve on the tank could act like a meter.

Chamber fueling a 1X hybrid takes ~0.045 bar of fuel, which is a value no affordable gauge will measure.
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Unread postAuthor: Technician1002 » Fri Feb 04, 2011 12:11 am

Since when is a U tube Manometer expensive? Some cheap tubing, a ruler, and some water and it's done.
http://www.engineeringtoolbox.com/u-tube-manometer-d_611.html
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Unread postAuthor: cfb_rolley » Fri Feb 04, 2011 12:31 am

So, how come metering a mix by measuring chamber pressure rise isn't commonly suggested? To me, that seems like the most simple method of metering, because all you'd need is a sealed chamber, a propane bottle connected to the chamber and a pressure gauge?
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Unread postAuthor: Crna Legija » Fri Feb 04, 2011 4:12 am

people are lazy and don't want to replace burst discs
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Unread postAuthor: cfb_rolley » Fri Feb 04, 2011 4:21 am

Oh jeez are you serious? If that's the only reason then I should have built a hybrid years ago and should start planning one right now.
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Unread postAuthor: jackssmirkingrevenge » Fri Feb 04, 2011 4:30 am

cfb_rolley wrote:To me, that seems like the most simple method of metering, because all you'd need is a sealed chamber, a propane bottle connected to the chamber and a pressure gauge?


I disagree, volumetric metering with a syringe is by far cheaper and simpler. The issue is that it's only suited for smaller chambers or low mixes.
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Unread postAuthor: cfb_rolley » Fri Feb 04, 2011 5:25 am

Mm well yeah, for a combustion or low mixes that would make sense but only needing a couple of fittings and a decent gauge and no need for meter pipes or multiple ball valves and regulators and the such. Maybe I'm just ghetto or not thinking correctly but I kind of like the idea of a tank, maybe a hose, a ball valve and a good pressure gauge.
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Unread postAuthor: spud-freak » Fri Feb 04, 2011 6:38 am

i will make my combustion to a hybrid with a 1x mix not higher!
(because the PE tubes)
i'm using propane gas.. i thinkt the best mixure of the gas is 4.2 really?
my question is, would this shema work for a 1x mix?

thanks
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