An air cannon.
What could it be?

What's this collection of PVC parts? Here's a hint: I used it when I played Wilbur in Hairspray. The other actors kept calling me a "real-life Wilbur".


IT'S A CONFETTI CANNON! Technically, an air cannon, but we were only going to use it for confetti.

I went to my local surplus store for the parts, particularly the Schraeder valve, but they didn't have anything. I did pick up a pressure gauge, but it's a formality.

I actually got all the parts from Lowe's. I was going to make it electrically triggered by using a 24v solenoid-activated sprinkler valve and three 9V batteries... but the biggest valve I could find was 1.25", and that would have required an extra $10 in parts.

The valve
Inserted valve

The valve was surprisingly difficult to get. The Discount down the street only carried rubber snap-in valves, rated to 40PSI. I wanted something more reliable, especially since I doubted the width of the PVC matched the width of a tire rim.

I eventually got this beauty at the Tire Kingdom. He doubted its existence, then checked with someone out back. He was so surprised to find it that he gave it to me for free!


It didn't take long to make. Just cement everything together. I couldn't give the last fittings the quarter-turn they deserved, though.

It took forever to cure: two whole hours before I could pressurize it. I took it to a park and fired it off at 20PSI using paper scraps. After the first "POP", I was suddenly surrounded by kids who wanted to try it out.

It worked at a performance at the theater, but leaked like the dickens. I couldn't keep it pressurized for more than a couple of minutes. The Discount down the street proved useful for this: I got some "Tire Slime", a liquid, non-petroleum sealant. ("Fix a Flat" uses petroleum-based solvents, and I didn't want to take a chance dissolving and weakening my pressure chamber.) At the second performance, it held pressure much better, but still not perfectly.

I brought it home and used JB Weld on the leaking part. 24 hours later, I pumped it up to 40PSI.


I couldn't believe it. I pumped it up to 80PSI and turned it upside down to get the Tire Slime into the hole.

That was the plan, at least. As soon as I picked it up...


Yup, exploded.

Keep in mind, this was 2" Schedule-40 PVC, rated to 280PSI. I had chosen it over my more-desired 3" Sch-40 PVC because the 3" pipes specifically said "non-pressure" on them. (What? It's Schedule 40, for Pete's sake!)

I think the fittings were non-pressure. Three of them shattered: two elbows and a tee. I was wearing thick clothing and facing away for just, I say, just such an emergency.

I'm going to try rebuilding tomorrow. I'll go to the sprinkler store down the street for pressure-rated elbows. The cannon will be a little smaller, and the base won't be a complete square: I want every fitting to be turned 90 degrees, as expected. I'll probably wind up with all elbows and/or U-bends and a cap.

We can rebuild it. We can make it better...