SpudFiles

i have had some experince with cannons and iam looking forward to build a piston valve cannon but iam wondering why no one ever takes thier piston valve cannons above 120 psi when the brass balll valve for ativation is rated up to 600 psi? also could i take a piston valve cannon up to 200 psi saftly

in PVC? no, not safe

To elaborate on what spudshot said, the ball valve might be rated for 600 but PVC is only rated to 160 in the best conditions. 120psi with PVC is stretching the limits of it turning into a frag grenade. A chain is only as strong as its WEAKEST link.

"The PVC is only rated to 160psi in the best conditions"
If you have a 6" chambered piston cannon, sure. Most people don't.
(Wait... you are using austrialian pipe, right? Our pipes are rated to different pressures than yours)

"120 psi with PVC is stretching the limits... frag grenade"
What? See the above comment, coupled with the fact that those ratings have a saftey factor of something like 4 in them.

My responce: Use small diameter and/or sch 80 PVC, and minimize the piston mass to minimize piston slap.

My therory: the real reason 120 psi is the commonly touted limmit is that most compressors don't go above that.

I have a metal piston gun I pressurise it to about 275 PSI.
Ballvalve has no problems with it.I guess the rating is about the teflon seal leaking a little above a certain pressure.( wich mine does'nt)This would be bad in a water installation or something that has to operate for decades.If U would use as such a small leak would make it "not work".We use em for a completely different purpose.Anyway..the metal ballvalve I use won't blow up or anything..

thanks guys, i guess ill take ur advice by not going up too high but i should of let u know that i was gonna use 2.5 inch sch 40