pic: T-Shirt Launcher, still needs a chasis

[Daniel_LaFleur]

Originally Posted by Bruceb

I knew we would get some warnings about the PVC. We have 2 GE engineers on our team and they don't see how this PVC can be a problem. We did not buy the cheap unrated PVC from Manards, this is all pressure tested and pressure rated PVC. The 3 in dia reservoir is rated at something like 320 psi. Don't remember the exact spec but it was WAY higher than the 60psi we intend to carry at max. I was thinking about wraping it in fiberglass cloth and epoxy just for safety but I realy don't think it is an issue. I can't help thinking that the accidents have been caused by using the unrated pipe or overpressurizing it. Any way. The chambers are gasketed at both ends with a spring loaded deal that seals both ends of the chamber. We do get a little leakage here but not much. I think at max elevation and 60 psi we could launch a rolled up t-shirt about 200 ft. Thats a guess as we have not tried it outdoors yet but it hits real far up the wall indoors.
Bruce

I can tell you, first hand, that those warnings are for good reason. I have had a 1 liter, 400+ PSI pressure rated PVC volume explode less than 2 feet away from me while holding less than 100PSI air. I can tell you that I am truely lucky that I came away with no injury (to speak of ...).

This accident was not the result of unrated PVC or overpressurizing it, or even shock loading it (Like you are doing with the cannon). This was the nature of PVC and of how it fails. PVC gives little to no warning before it fails and when it fails it fails catastrophically.

While I Highly recommend that you replace the PVC, if you are dead set on using PVC then I would suggest wrapping all of the PVC parts (My suggestion would be Twaron over your idea of Fiberglass).

While building devices like this is cool and a great learning experiance, please, please, please don't ignore the safety concerns just because you don't think there is an issue. You need to Know all the safety issues, especially if it's going to be shown to the public.