How-to: Syringe Fuel Metering

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.
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Zeus
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Mon May 09, 2011 11:52 pm

But in my experience (which is minimal), the check valve would pop before the syringe was pushed back.

Also if too much gas was put in the syringe then there would be no way to vent it. I like your thinking though.
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Lockednloaded
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Mon May 09, 2011 11:59 pm

You could just have a stronger spring in the 2nd check valve
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jackssmirkingrevenge
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Fri May 20, 2011 7:57 am

Helpful tip: you can get 100mL syringes a couple of dollars that will allow you to fuel combustions with up to 2.5 litre chambers in one go, so this method is not strictly limited to "mini" launchers.
hectmarr wrote:You have to make many weapons, because this field is long and short life
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Technician1002
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Fri May 20, 2011 12:11 pm

By making your own pistons you can make metering syringes of any size.

I have toyed with making a dual syringe for metering air and fuel together much like an epoxy syringe. Either a pair of pipes with the proper ratio in cross section is needed or a lever to push the plungers in the proper ratio would be needed to dispense a purge fuel air cycle into a launcher. It would be for rapid reloads.

In medical supplies, they are not IV syringes. They are feeding tube syringes. The tip is larger than an IV syringe so a needle won't fit on it.
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Sat May 05, 2012 12:22 pm

is the ideal concentration of butane always 3%
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Crna Legija
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Sat May 05, 2012 12:30 pm

nope its 3.23% :lol:
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Sat May 05, 2012 12:33 pm

haha ok tanks :D
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JDP12
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Sat Jun 23, 2012 8:11 pm

sorry to kick this up, but how do you determine the dead space volume of your air pump?
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jackssmirkingrevenge
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Sun Jun 24, 2012 1:50 am

You can fill it with water for a precise measurement, or guesstimate based on internal diameter. It's critical for small items like cartridges, but not so much for larger chambers.
hectmarr wrote:You have to make many weapons, because this field is long and short life
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