abs pressures

[dinsdale]

i have just read on a forum here that pvc should be used for pneumatic cannons and not abs since it isn't pressure rated.
does anyone have comparitive info on the burst point of ABS vs PVC?

i just built a pneumatic cannon from ABS, it's 2 " ID, for both the chamber and barrel, and both are 36" long. it is an inline cannon with an orbit watermaster valve (not modded yet) i've been launching all kinds of stuff at 95 psi. I would much rather have a piece of ABS bulge and rupture, than a piece of PVC grenading on me. I'd like to hear the opinion of an air cannon veteran on the matter.

BTW my cannon is very ugly and hillbillyish so i didnt feel the need to post pics

[Velocity]

A well-constructed PVC pneumatic will NOT blow; thats why I use it. Sure, if you made two cannons, one of cell-core PVC and one of ABS, i'd use the ABS; you are correct in wanting to be closer to an ABS rupture than a PVC explosion.

The problem is, an ABS cannon cannot hold the sustained pressure, and therefore, over time, will undoubtedly fail at some point (considering you take it up to 95 PSI). A well-constructed PVC cannon will not explode unless used: A) above a safe pressure (generally 100 PSI, +/- for smaller/larger bore cannons, respectively); B) in an extremely cold or hot environment; C) in any stupid, non-common-sense-using manner.

PS: wrong section to post in

[dinsdale]

thanks, i realized as soon as i posted i was in wrong spot.

one other example of why i like abs is if you take a piece of abs and a piece of pvc of equal size and attempt to destroy it (eg with a sledgehammer, or crushing in a vise) it takes substantially more to break the abs

[dinsdale]

I have done more testing with my abs gun and found it can keep shooting at 95-110 psi without failure, it has had probably 100 shots through it and i plan on testing with higher pressure just so that i can share the results

[drac]

You most likely have the rare, pressure rated version of ABS that isn't cellcore. It's generally harder to come by and more expensive, but I would prefer that over PVC.

But since I can't find pressure rated ABS for crap, I have to stick with PVC.

[cannon freak]

Are there any pressure ratings on the ABS pipe? Where did you get it?

[dinsdale]

actually it was more than twice the price of non-pressure ratec pvc, and is thick walled.
it didn't appear to be cell cored when i cut and drilled it.
on the side it says abs-dee-dwv t1g2

edit: no pressure rating, got it at a home depot

[SpudStuff]

Pressure rated ABS is an oxy-moron

[drac]

Pressure rated ABS is an oxy-moron

No it's not. There actually is a pressure rated type of ABS, it's just extremely rare. Why don't you google it before using fancy english terms on us.

[dinsdale]

well i've now had my non-rated abs cannon past 125 psi without failure, hopefully i'll have higher figures tomorrow

[dinsdale]

I've just went through a bag of potatoes at 155 psi in my non rated everyday abs sprinkler valve cannon (the valve is rated at 80 psi) so far no failures, next test 170 psi

edit, ps i modded the valve before crossing 120