SpudFiles

Im not 100% sure, But ive heard lots of other people say that its true.

Personally, id think water would have more force.

None of them has more force. 100 PSI is 100 PSI is 100 PSI.

It's all about failure characteristics.

You have a PVC failure with 40 PSI of water, the pipe cracks and leaks.

You have a PVC failure with 40 PSI of compressed air, the pipe explodes into little pieces that are flung everywhere.

180 PSI is not safe, but I did it anyway. Know why? Because I trusted my pipe! Not a smart choice, (this was my first cannon), but it did let me get a little distance...

i would think water and air pressure would be the same force in pvc...maybe im wrong.

mine has a 18 foot long,4 inch diameter barrel.It is a pnumatic . check it out

http://www.spudfiles.com/forums/viewtopic.php?t=1747&

180 pounds for square inch are 180 pounds for square inch no matter what is the pipe full with.It's another story that with air there will be more shrapnels.

My largest gun is a 7 foot bazooka. It's combustion chamber is 3 feet long, 4 inch diameter and reduces to a 4 foot long 2 inch diameter barrel. I get well over 700 feet of distace. I know this because I brought it to a golf course (before it opened, there was no one on it) and it cleared a 220 yard par 3 from the tee box.

The reason air is more dangerous than water is because it holds more energy. Remember, a gas has more kinetic energy than a liquid. That's why steam burns are so much worse than hot water burns.

My most powerful cannon is my 1inch valved pneumatic... 3inch by 24 inch chamber, 1.5 by 28 inch barrel. Not exactely efficient, but it can still blast a potato over 300 yards.

my most powerful cannon has a 20 foot paintball barrel, a 4" x 18" chamber nd used metered propane. i cronied 1231 FPS with a paintball

My most powerful gun is a QEV copper gun and can shoot through 1 1/2" chipborad.

And iv taken one of my guns to 300psi once and it was fine, it was made of copper.

SpudStuff wrote:my most powerful cannon has a 20 foot paintball barrel, a 4" x 18" chamber nd used metered propane. i cronied 1231 FPS with a paintball

I would like to see a picture of that, because the chances of getting supersonic with a combustion are slim to none.

My call? bullshit

-1 wrote:I don't see why not, the pressure ratings on those pipes are like 300+ so i would think 180 psi is safe enough.

Maybe so

But no matter what material you are using, you want to incorperate a safety factor into it. The pressure rating put on the pipe is lower than what the pipe can hold; i believe it can hold twice as much pressure.

However, like others have said, gas is not intended to be used in these pipes, so it greatly increases the chance of the pipe bursting. Anyway, I wouldnt pump pipe rated 100 PSI FOR AIR to 100 psi... you just dont want to tempt fate

So pounds per square inch water is different from pounds per square inch created by air huh??
So a pound of feathers is lighter than a pound of lead...mmm

that's just....silly

I thought we just said it wasn't any different???? It's all about failure characteristics and the amount of times more air expands then water.

Plus, to add to above, a 20 foot paintball barrel would be awfully hard to keep straight, don't you think? I'm constantly rolling over my 8' 1-1/2" barrel to keep it from bending in my closet... my 5' 3/4" barrel flexes enough, I can't even think of how much a 20' foot barrel would flex...

Brian the brain wrote:So pounds per square inch water is different from pounds per square inch created by air huh??
So a pound of feathers is lighter than a pound of lead...mmm

that's just....silly

Have you ever dropped a pound of lead on your toe? I think it might just hurt a little more than a pound of feathers.

EDIT:

I just though that this is interesting:

1972:Plastics Pipe Institute recommends against thermoplastic
pipe for above-ground transport of compressed air or gases unless
encased in shatter-resistant materials

1986: ANSI standard B31.8 "Gas Transmission and Distribution
Piping Systems" prohibits plastic pipe over 100 psi and in all
above-ground installations unless enclosed in a conduit or casing
of sufficient strength

1988: OSHA memorandum "Safety Hazard Information Bulletin on the
Use of Polyvinyl Chloride (PVC) Pipe in Above Ground
Installations" recommends against the use of PVC pipe for
compressed air

1991: OSHA announces that the use of PVC pipe for above ground
transport of compressed air or gases (unless pipelines are encased
in shatter resistant material) will be a violation of Section
5(a)(1) of the OSH Act