Barrel Sealing Tee Valve

[TalonXxX]

I built my first barrel sealing valve, just like Izzy's "Son of a Zonker" (http://www.geocities.com/izzydoesit_99/SOZ.gif) Everything is pretty much identical to his cannon. All 1" pipe and 3/4" barrel. I have a brass T, one connected to the gun, one to the air source, and one to the blowgun. When I tested it out it didn't work. The piston was definately sealing the barrel but I don't know if air was even entering the chamber. I have a pretty nice equilization port on the piston so that shouldn't be a problem. I'm wondering if I should have two ports on my end cap... one for blowgun and a separate for air source because it seemed like air was going straight from air source through blowgun and the chamber wasn't given a chance to evacuate. Also, maybe my piston is too large? Should my piston be fairly tight with the walls of the Tee? Any other suggestions to troubleshoot this problem would be much appreciated. Thanks

[TfAv1228]

ok well first off its called a diaphram not a piston. It should not be tight against the well and it should be flexible if its not flexible it cant seal the barrel or get the air to the chamber. Do you have a pilot valve to release the pressure from behind the diaphram?

[TalonXxX]

Yes, I currently have a blowgun as the pilot valve. The diaphram is neoprene, so it's flexible and it does seal the barrel, so that isn't the problem.

[TfAv1228]

hmm well that diagram you linked to says a sch40 1" T not a brass one so something might not be sealing. You should have 1 place for a pilot valve and 1 place for your air source not each on the same hole. And what exactly isnt working is the diaphram not releasing off the barrel or what?

[TalonXxX]

I said its a brass T... never even mentioned sch40 up there so I don't know what you're reading. I have a brass T, one end is air source, the other end is my gun and the other end is my blowgun. That is one possibility... the diaphram might not be releasing off the barrel. It sounds like that's what's happening. Know how to fix that?

[TfAv1228]

i would say no spring or atleast a weaker one. The diaphram should not be touching the barrel when there is no air pressure so make sure thats not happening.

[WOW!!]

I know that in a 4" tee a 3" end cap makes a perfect fit for that.

NOTE FROM PIMPMANN22- Congrats on kicking a ~5 month old topic! Seriously how do you guys even find these dead topics? Seems like you have to try and do so, rather then it being on accident...

^wow, some one is pissed off.

[Shrimphead]

How big is your equalization hole? If it is too big, then the diaphragm won't be pulled off of the barrel. This can be a big problem with small pilot valves such as a blowgun. The spring is probably also contributing to the problem.

[TalonXxX]

lol I fixed this problem 5 months ago... just failed to update the thread... the completed gun is under Finished Cannons on Spudtech