SpudFiles

Hey guys, i was wondering if you could give me some info on what you think. I was thinking about making a propane powered pneumatic. Just using the propane for an air source. I was thinking about making a 1" steel stock, 3/4 in QEV, and a half inch barrel. I wanted to use the stock as the chamber.
Does anyone see any major problems with this?
Steel pipe should hold very high pressure right?
How much pressure is propane usually at in the bottle?
Also would this be dangerous considering propane is so flammable?

Edit: I hope this is the right section to post this in.

No problems, works great.

propane pressre is dependent on temperature, you can find a chrt on the vapor pressure of propane at certain temps via google.

Carlman wrote:No problems, works great.

propane pressre is dependent on temperature, you can find a chrt on the vapor pressure of propane at certain temps via google.

Better yet, look at the SpudWiki page on propane;
http://www.spudfiles.com/spud_wiki/index.php/Propane

The pressure in the tank at a particular temperature is the vapor pressure of propane at that temperature assuming (1) the tank is at thermal equilibrium (you aren't removing gas to fast) and (2) the tank contains some liquid propane.

So by what the wiki says, at 70 degrees if i just filled the gun it would only be 110 psi? Or did i completely screw that up.

Yeah, the pressure would not be able to exceed 110psi, because any more propane you add to the chamber would just condense to become a liquid.

OK Thanks a lot for the info. I saw this idea on here a while back and wanted to make one. I just didn't know that propane was at that low of pressure.

May I suggest an alternative? CO2. You'll get 800psi from a tank.

I tried and tried to get propane to work...I haven't had any luck. I'm not giving up hope though cause I dont have the money for a CO2 regulator right now. lol. when I hook it up to my bbmg it will shoot hard for about 3 seconds then it will just drop off to almost no fire at all. =\ I dunno.

@boom_o_matic
what size tank do you have??

I am hope you understand that what you described is perfectly normal since propane cools off when it evaporates (just like anything else)

you'd either have to: wait till it heats up to normal temperature or find some way to heat the tank

deathbyDWV wrote:
Edit: I hope this is the right section to post this in.

Probably not...

(NOT FOR HELP-ME POSTS!)

You are new here. You will catch on. No harm done.

-its a small camping propane tank
-heating a small, high pressure, tank of flamable liquid??? I see several red flags goin up right there. lol. or do you mean heating the chamber on my gun? I tried using a coiled air hose and a regulator. neither worked.

boom_o_matic_2.0 wrote:-its a small camping propane tank
-heating a small, high pressure, tank of flamable liquid??? I see several red flags goin up right there. lol. or do you mean heating the chamber on my gun? I tried using a coiled air hose and a regulator. neither worked.

The heating is just to replace the heat lost to evaporation, not to elevate the temperature. Don't use flame. Use a pan of warm water. Keep the temp under 120 degrees. Use a pressure gauge if needed and regulate the heat to control the pressure. Keep it under 150 PSI.

-just dunk the entire tank in hot water or part of the hose as well?
-keep the propane pressure under 150psi?

boom_o_matic_2.0 wrote:-just dunk the entire tank in hot water or part of the hose as well?
-keep the propane pressure under 150psi?

The hose should be fine. The liquid evaporating is the source of the cold spot that needs replacement heat. The hose won't get much of a chill unless you are pumping liquid in it.

I try to keep the tank sitting straight up so that it wont pour liquid propane into the hose.