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Re: Air Cannon
MARS Team 1523 created a t-shirt launcher over the summer too and has also run into school approval issues. Initially it was approved for use as long as it was mounted to a robot. Now the high school will not allow the "launcher's" use without team liability insurance. (We've found that calling it a "launcher" rather than "shooter" or "air canon" garners greater support. The earlier post about painting it is also true)
As far as safety, we discussed the design with an ME, EE, & PhD Chemist. (MARS used heavy wall schedule 40 PVC (whole thing) and fill the launcher to 80 psi.) Here were their thoughts : Regarding PVC bursting, it is dependent on the pressure and size being used. Typically what will happen is a crack will occur and slowly propagate at lower pressures. At the pressures being used in our launcher, crack propagation causing more than a leak would probably only occur if a weakness was present (such as the PVC was poorly made - which could be said of any material being used) or if mistreated (pouring a solvent on it, using a sledge on it, etc.). Where care must occur is in the glue joints, which if not done properly could leak or, if very poorly done, come off rapidly.
With others in the CD community suggesting PVC explosion, shrapnel, etc, I'm curious if they still feel this is a concern with launchers built using designs similar to MARS (heavy wall schedule 40, 80 psi fill).
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