Idea for pneumatic gun using CO2

[-T0OL-]

ok I'm planning on making a CO2 powered gun my plan was for it to look something like this

Code: Select all

+-----------------+--+------------------+---+\ 
|                 |  |                  |   | \================== 
|                 |  |                  |   | /================== 
+-----------------+--+------------------+---+/ 
                   ^         ^            ^ 
CO2 tank--^       /          |            | 
                  |          |            | 
Ball valve--------/          |            | 
                             |            | 
chamber -------------------- |            |
                                          | 
sprinkler valve ---------------------------

and then the last part is the barrel. 

my plan was to have a regulator between the ball valve and the CO2 tank so that i could fill the chamber to 100psi or so then close the ball valve and use the sprinkler valve to fire the gun. I dont know if this is the best or easiest way... But what i wanted to know is what can i use to connect the CO2 canister and regulator to the PVC/ABS tubing (is abs or pvc stronger? )?

any help/comments/suggestions appreciated.

[boilingleadbath]

...that's nothing revolutionary, and I'm sure searching our pneumatic cannon section will show you a whole bunch of examples of (basicaly) this design.

...and for the record, we generaly reccomend using pressure-rated (NSF-PW) PVC. (although ABS is somewhat better mannered in the cold - which might be relevent here)

[-T0OL-]

yea, it wasnt meant to be anything revolutionary since this will be the first gun i've made. Any ideas what the thing that would connect the CO2 tank to a regulator would be called? (and the regulator to the ball valve if that is a special part)... im currently looking over previous posts to see if i can spot one.

[CS]

Shu-min-a-gona. Thats what its called:-p

Which type of regulator did you intend to use? A air compressor one? If you were to buy one for a paintball tank itd have threads to fit a tank.

[-T0OL-]

I'd buy a regulator from a PB store since i know it would work for a CO2 tank. would the other side of the regulator (non tank side) have just normal threads on it?

[Gnobbes]

Just keep in mind that CO2 comes outcold. I've heard that PVC gets brittle when it gets real cold.

You might consider using copper and steel for this one.

[POS]

how does the rubber of the piston valve react to those extreme cold ?

[-T0OL-]

at first i was going to use PVC or ABS but i think i will go with copper then just paint it, it handles the cold better and more PSI from what i've heard... and POS did you mean sprinkler valve when you said piston valve?

[)DEMON(]

Plastic sprinkler valves will also not be a good idea with the constant cold temparature of co2. Piston valves are not very hard to make if you know what you are doing. You could easily use a paintball cylinder as a co2 regulator but then you would need a paintball regulator. These are hard to find, here's the web page with palmers regs.: http://www.palmer-pursuit.com/online-ca ... ilizer.htm

Copper would make a good barrel and piston housing but metal pipe (like plumers use) will make a better chamber and should be able to hold the pressure if you accidently let the full 850 psi into the chamber.

[-T0OL-]

Ok thanks. would there be any issues connecting copper to steel directly?

[)DEMON(]

The copper needs compression fittings on the ends. These are threaded so you can connect it to normal metal pipe with galvinized fittings.
Hope you know how a piston valve works. Do lots of research befor you buy and build, this is a big project and you are dealing with high pressures.

The good thing about those palmers regulators is they are adustible. So you could change the pressure from 100 to 500psi.

[-T0OL-]

ok thanks, i have read about how pistons and diaphragms work. So if i used a piston that would turn the gun into a coaxial right, instead of it being linear?

[MrCrowley]

it could or you could do an over-under design using chamber or barrel selaing piston valves.

[-T0OL-]

Which of the three would be easiest to make and maintain... or do they each have pro's and con's

EDIT:: also would i need a regulator on a 12g cartrige?

[MrCrowley]

over-under barrel sealing piston.,mind you if you had a chamber sealing piston you can fill up the co2 from the chamber.