SpudFiles

Hello, I am currently working on building an airsoft gun using an 1/8" QEV activated by a 3 way mechanical valve(Clippard MJVO-3). I am planning on using propane as a proppelant just like if you were using co2, no combustion. But I was wondering about the adapter for the tank, I am using an adapter off of an old coleman portable propane heater designed for a portable coleman type propane cylinder. I am wondering if this is going to work o.k, cause some liquid comes out if the cylinder is lying down, like it will be in my gun.

Do you guys have any ideas or tips for this kind of setup?
Also am I going to get a high enough volume of propane coming out of this setup to keep up with a semi auto opperation?

You can use propane for pressure in a pneumatic, however if you are getting liquid out you would not want to use it. If you position the tank to where only gas is coming out your good.

The vapor pressure of propane is very temperature-dependent (and also rather low at all temperatures), so you may have issues in cold weather. Also, be aware that running semi-auto will turn this gun into both a fire hazard and carry the danger of asphyxiation, but both those dangers are negiligible if you use some common sense. You won't have any problem with liquid propane coming out your gun, it boils far too quickly for that.

So far as adapters go, this thread helps. I used the method DYI suggests, it's cheaper and easy.

How can I keep the liquid from coming out? Isn't there some kind of a nozzle or something that will keep the liquid from coming out?

Also what is asphyxiation?

Also what is asphyxiation?

Not breathing.

http://en.wikipedia.org/wiki/Asphyxiation

Asphyxia or asphyxiation (from Greek a-, "without" and σφύξις sphyxis, "heartbeat") is a condition of severely deficient supply of oxygen to the body that arises from being unable to breathe normally.

There is no nozzle that I know of that can stop a liquid from flowing. Just don't tip the bottle upside-down and you won't fill the chamber with the liquid. Allowing liquid in will cause a significant loss in power, as the liquid has to boil before it can expand.

Gases like propane and butane cause something more like suffocation I guess. If you inhale too much of them, they are too heavy and diffuse too slowly for you to expel from your lungs and free up enough lung capacity to take in enough oxygen to stay alive. A few years ago somebody in my school died in a chem lab because he thought it would be fun to huff butane out of an Erlenmeyer flask. He was dead before medics arrived. So long as you don't try to inhale the stuff you should be fine.

Funny, I am using exactly the same thing for my semi-auto, except I am using a 1/4 inch QEV.

The setup you have in mind will work well. As I intend to use co2 I must purchase a regulator + CO2 tank + hire a large CO2 tank for filling but my gun will be a lot more reliable because the pressure will be constant.

I suggest you make the chamber on the 1/8 QEV fairly large because propane will give you a fairly low pressure.

Not nessasarily true if heated pressure can be increased, i have considered charcoal hand warmers for this purpose.

*cough*

*splutter*

haha. IIRC, Singularity did a how to on making a propane adapter for exactly such a purpose..

or you just go to camping store and get a propane bottle fitting to 1/4" NPT. I got one for $4.

metalmeltr wrote:Not nessasarily true if heated pressure can be increased, i have considered charcoal hand warmers for this purpose.

I'm not sure what you mean by this. So far as I know, all hand warmers use the oxidation of iron to produce heat. The other stuff is in there to speed up the reaction and distribute the heat.

some propane torches have 1/8" female NPT threads if you unscrew the "torch part" leaving only the needle valve.

Most are 1/4" compression fitting threads. Like explained here...