Is that PVC? If so I would recommend immediately decommissioning that cannon and rebuilding it with pressure-rated ABS or metal. PVC is pressure rated for liquids, not gases. When PVC fails, it shatters, which, when filled with air sends sharp shrapnel flying. This shrapnel can easily blind or otherwise seriously injure someone. The question with PVC, as with any material, is not if it will fail but when it will fail. It might last 10 years or it might last a month. With pressure-rated ABS or metal, the risk of failure is only slightly small, but the risk of injury when said failure occurs is orders of magnitude smaller. The risk of failure is very small, but the risk or seriously injuring someone is just to great.
Originally Posted by docdavies
We've been designing T-Shirt Canon's for a while but have been singularly unsuccessful at getting permission to build one from the school or school district we are affiliated with.
How did you folks go through the process of obtaining permission to build and then demonstrate your shooter at school events?
We just built one (over the summer, in a student's family owned shop), then went to the administration and asked if we could use it a an assembly and at football games.