[Dan Richardson]

I Believe the rating is posted on the side of the pvc? I remember that it was deffinately on the side of the pvc glue bottle for the joint strength. The pvc is usually not the concern however it is the joints. Improper usage of pvc glue can end up in caps flying off in a spectacular like fashion. Another common problem with pvc is under sunlight it can become brittle greatly reducing the strength of the pvc. If put under pressure you can have a failure to occur, and thats no good.

Regardless its still a cheap and effective option. For a freshman engineering project I used pvc to build a marsh mellow launcher. I have considered modifying it for t-shirts as it would work effectively but It would be a one shot deal and we'd like to get multiple shirts fired before pressurizing.

In my marsh mellow launcher I only had one failure and it was due to improperly gluing. In this case I actually did not let the resin settle before I tried it he he. But after regluing I was able to consistently hold about 100 lbs of pressure in a 2 ft long by 2" diameter pvc pipe. Its fun to shoot a marsh mellow at ~ 280 fps. It is however not fun to get hit by one :-)

I've seen shirt launchers being launched at approximately ~40 psi successfully and sometimes almost too far.

Without testing however fatigue could be a concern, it may be something you'd want to consider rebuilding every so often.