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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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Unread postAuthor: linuxexorcist » Fri Feb 04, 2011 8:12 pm

the height determines the pressure:
P=pgh
P:pressure (Pa)
p:density of the liquid (kg/m^3)
g:force/acceleration of gravity (N/kg or m/s/s)
h:height of the column (m)
more info (and practical use as a pressure guage) can be found HERE
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Last edited by linuxexorcist on Fri Feb 04, 2011 8:49 pm, edited 1 time in total.
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Unread postAuthor: saefroch » Fri Feb 04, 2011 8:18 pm

Ohhhhhhh that's how they work!!!!
Yeah, I never knew
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Unread postAuthor: spud-freak » Sat Feb 05, 2011 3:23 am

thanks guys for the answers..
today i'm working on a hybrid with steel pipes,
but the part i didn't understand is do i have to made a pre-mixing chamber, or can i mix the 14.7psi and up with the gas in my ignition chamber?
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Unread postAuthor: spud-freak » Sat Feb 05, 2011 6:45 am

i'm working on a hybrid, how much of mapp gas did i need for a 3x mix?
43.5 PSI Air ..
and what the steps?

1. mapp gas fill in the pre-chamber with the gauge and then inject to the ignition tank
2. open the 2 valves above and fill the ignition tank with 43.5 Psi of air

are the steps right so?
guys thank you for the nice support:-)

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Unread postAuthor: Technician1002 » Sat Feb 05, 2011 9:31 am

Usually air is not run through the gas meter tube. With the tube full of air, adding fuel then meters fuel with the remaining air. Most fuel meter tubes are purged of air. This way when pressurized with fuel, the volume and change in pressure is metering fuel only.

Normally the fuel meter tube is filled with fuel to a given pressure so a metered volume of fuel is added to the chamber. The fuel is normally added before the air to the chamber so the end pressure in the fuel meter is near 1 atm.

Using HGDT, the section on metering pipe calculations will provide the proper pipe volume and pressure for metering your chosen fuel. This page shows the parameters for designing the fuel meter.

http://www.thehalls-in-bfe.com/HGDT/

The HGDT program can be found here;
http://www.thehalls-in-bfe.com/HGDT/

I am not going to spoon feed and give you the volume and pressure to use. Use the software and study it. Remember, meter the fuel into the chamber and then add air to to proper mix pressure directly into the chamber. Do not add air through the fuel meter.
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Unread postAuthor: spud-freak » Sat Feb 05, 2011 10:37 am

@Technician1002

you mean like that?

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Unread postAuthor: saefroch » Sat Feb 05, 2011 11:24 am

Technician1002 wrote:Usually air is not run through the gas meter tube.
Spudblaster15 wrote:Volumetric meter w/ integrated air fill port (Air through meter design)
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Unread postAuthor: SpudBlaster15 » Sun Feb 06, 2011 6:10 pm

saefroch wrote:
Technician1002 wrote:Usually air is not run through the gas meter tube.
Spudblaster15 wrote:Volumetric meter w/ integrated air fill port (Air through meter design)


Yeah, I was just about to post something like that in response.

Virtually every volumetric hybrid fuel meter built since 2007 has used the air through meter design. It aids in air/fuel mixing, and reduces the significant systematic error associated with fueling small volume chambers using low precision hardware store gauges.
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