SpudFiles

I see alot of reference to usng sch 40 pvc pipe for air cannons etc.
Yes sch 80 is better but using sch 40 for anything over 2 1/2 pipe is not the route to go.
After 2 1/2 the class 315 pvc is preferred as it is thicker in wall material and rated for 315 psi regardless of size.
a 3" sch 40 is rated for 260psi where as class 315 is rated for 315psi.
3" sch 40 wall thckness = .216
3" cls 315 wall thickness is .259
I used to do alot of irrigation work in my earlier years and learned something.
If building a large cannon, then hopefully this will help in you decision on material.
http://www.certainteed.com/resources/pv ... 06001b.pdf

yes getting 50psi extra on a 3" cannon is good but have you priced sch40 compared to class 315 pipe?
It's about 1 1/2-2 times more expensive on average. sch 40 works just fine at the pressures we use as long as people stay in a sensible range

SDR (Standard Dimension Ratio) pipe has the same O.D. as Schedule pipe, but with different pipe I.D. All SDR pipe in a series has the same ratio of O.D to wall thickness throughout the sizes, and thus has the same pressure rating.

PVC Pipe - Spud Wiki