syringe meter

jon_89 · Sat Jan 26, 2008 11:27 pm

So I am going to use a syringe for my combustion gun and I was reading the wiki and here is what it said "When the tank valve is opened the syringe plunger will move back. The tank valve is closed when the correct amount of fuel is in the syringe. The syringe is removed from the hose and the excess pressure in the syringe is released to the atmosphere. The syringe now contains the measured volume of fuel at atmospheric pressure." I get it but doesn't the propane leak out of the syringe if I don't cover the needle up?

VH_man · Sat Jan 26, 2008 11:32 pm

no, water does not fall out of the syringe when you turn it upside down does it???

I know, i have used this method, and it is 100% FAIL SAFE.

i can fuel something as small as halph of a film can accurately.........

jon_89 · Sat Jan 26, 2008 11:35 pm

Good point. Never thought of it that way. So what is your set up like?

VH_man · Sat Jan 26, 2008 11:40 pm

Basically, you take the Butane can, and you press the syringe on the top untill the syringe head gets forced up past where you need it to be.

then, remove the syringe from the butane can and push the head down to where it needs to be. then "squirt" the butane into the chamber and fire away...!!!!! lol.

its literally that simple tho. Im not sure what your butane can/syringe looks like though so it might be more complex for you.......

jon_89 · Sun Jan 27, 2008 12:05 am

Well I think for now I am going to use the blue bottles of propane because that is just what I got lying around. So then you have consistant firing? Man I figured when you took the syringe out of the butane can that all or most of the gas would come out.

VH_man · Sun Jan 27, 2008 12:41 am

well, most of it does. the amount you need stays in there tho

jon_89 · Sun Jan 27, 2008 12:52 am

Well if it works for you hopefully I can get it to work. Any idea how I would use the blue propane bottles?

Deterrent · Sun Jan 27, 2008 3:16 am

jon_89 wrote:Well if it works for you hopefully I can get it to work. Any idea how I would use the blue propane bottles?

The little camping gas cans? I'm going to put mine onto the little camping cooker, attach a hose to the gas valve on the cooker, open the valve, let the gas push the air out of the hose, then take some gas with the syringe.[/url]

SPG · Sun Jan 27, 2008 12:08 pm

Bit wasteful of gas isn't it? After all, what you're basically doing is filling your syringe with gas at almost the pressure inside the cylinder and then allowing that to vent and equalise with atmospheric pressure.

Obviously the eaiser your syringe slides the less pressure there'll be inside it, and if you could get one which was frictionless you could fill it with fuel at atmospheric pressure.

Hmm, so the plan is to design a syringe with the minimum friction caused by the piston seal, but one that still seals well.