SpudFiles

Hi guys, I was hoping I could get some help. I've gotten all my PVC together for pneumatic cannon with a 4 inch holding tank, and I need to get a valve on it. My first question is: Which is better, a tire valve or a bike valve? And for tire valves, a .453 rim hole or a .625 rim hole (which is a bit more bulbous)? And the most important question: what do I use to seal the valve into the end cap? I assume that I will drill a hole and then stick the appropriate valve in, then add the sealant. For the other PVC parts, I am using Oatey's PVC Primer and then the Oatey's PVC Cement. Should I use the same thing for the valve?

____Thanks for any help!

It doesn't really matter what you use for the valve. All three of them would work fine. I like using presta valves because you can screw them in which makes them a little more sturdy. The only problem is you have to buy a different fitting to use them with an air compressor. If I were you I would just use a schrader valve from a flat bike tire. For glue just use some kind of silicon like plumbers goop. Definitely don't use pvc glue for anything but pvc. It's a solvent so it actually welds pvc together. I'm pretty sure it's not an adhesive.

It is very sticky though

Anyway if you can't find a threaded schrader get the ones could 'pop-in schraders' they have a huge bulb on the bottom...just drill a smaller hole then the bulb and push it through and once you see a picture of one you'll know how it seals..

once you place it in no matter what valve you use make sure to add a good epoxy fillet just for good measure

The easiest way to install a pop-in valve:
1. Buy the one with the .625" bulb thing.
2. Drill a 5/8 (.625!)" hole in the middle of the end cap.
3. Put the thin part of the valve through the inside of the cap.
4. Put some sealant on the top of the fat part, where it will come in contact with the end cap.
5. Pull the valve through with pliers and twist it to get the sealant around more. Be careful to leave the thread protecting cap on the valve or the threads will be damaged and valve will be useless.

Yes, all the above ideas are great... however if you are worried about leaks between the stem and the pvc, use a chrome valve stem. You won't need any sealant. I'll edit my post and upload a picture....