Here is the sizing chart from flexpvc.com (where I ordered from)

http://flexpvc.com/PVCPipeSize.shtml

I should be using class-200 2.5" pvc pipe?

Hey guys, I ordered some 2.5" pvc to use as a tennis ball barrel, but the tennis ball seems too large for the pipe. The ball is a Penn 4, and should be standard size, but I really have to deform the tennis ball to make it fit in the barrel. To those of you who use 2.5 inch pvc for tennis balls, is t...

My 0.4 barrel is epoxied inside a piece of 1/2 inch PVC. The 1/2 inch PVC is then expoxied inside a copper 3/4 inch male adapter. The tolerances are fairly tight; I had to sand down the PVC to make it fit in the adapter.

Works like a charm

As far as actuating the valve is concerned, i would pilot with a blowgun valve and design some sort of electric solenoid/ plunger mechanism to actuate the blowgun.

This will yield much better results while still allowing for automated firing.

logical thought progression: First thought- well, if it is going to be ridiculously over-engineered, you can use a passive photo-detector and op-amp bufer circuit to turn on a mixing fan if something, (aka a pesky rodent), disrupts the sensor. Use this in combination with an amplifier to get more t...

Hey guys, I know this post is long, but it might be of interest to some of you... I'm currently a Mechanical Engineering undergrad at the University of New Hampshire and I'm working on a research proposal to learn more about combustion theory in finite volumes--specifically, the conditions that need...

I laminate a sheet of aluminum foil and cut out circles. It works very well--just pressure test it to find out what kind of psi it can retain..

(This will vary depending on the thickness of both the foil and the lamination. 1 layer of foil + 1 side laminate is good to approximately 100 psi)

Yep, MAPP is good for this setup.

According to the Latke Tests, MAPP yields slightly greater muzzle velocities than propane does, but it equates to about an 11% velocity increase for a 300% price increase.

http://www.burntlatke.com/lpmapprussets.html