FIRST air cannon robots PVC??

[RyanN]

Originally Posted by Andrew Schuetze

When I get a bit more time, I'll add links to the various threads on C.D. on this topic.

My question is how / where does one get a definitive answer as to the pneumatic pressure rating of schedule 40 PVC? I was intrigued by the team fusion air canon last year and then decided to add one to our 2005 robot this August. I'll post a picture of the prototype mounted on my classroom workbench. It works okay. Based upon three weeks of development, what I perceive to be limiting the performance is the restriction of air flow from the storage tank via the 0.5 inch fitting. Everything else is the same 1" diameter as the sprinkler valve and then expands to the 3" diameter at the back of the muzzle.
I've seen about three cannon systems which are using PVC pipe as the pressurized air storage system here on C.D. People have commented that PVC pressure ratings are for water systems and in fact the fine print at the store indicates use for water only.

My fear is that a bump into a doorway or drop on the floor may start a crack in the PVC pipe and eventual lead to catastrophic failure.

How do I know if I am being overly cautious or just being prudent?

APS


Toltech prototype

We use 60 PSI and we can shoot quite far, so we don't use any crazy pressures like many people are assuming. At most we have put 90PSI in when we were trying to shoot a croquet ball across the football field, but no one was in the stands or the field. Also, we use some type of PVC sleave in the middle of the cannont to prevent it from expanding too much. Just a suggestion, if you get a sprinkler valve that is rated at 24 volts, don't run it in series with a spike. The spike leaks enough current to keep the valve on after releasing your firing button, and it will not work right with only 12 volts. We use 3 9V batteries in series going through a relay connected to a spike and it works well for us.