SpudFiles

Well, as some of you know, I have been having trouble with my sprinkler valve, and I did put a ball valve infront of the valve, filled up the tank, and then released it to see if it would equalize, and it didnt. all the air just rushed through, making a really loud farting noise. Ive been trying to make something close to one of joel's cannons. http://www.spudtech.com/detail.asp?id=31
I have a 2 foot long 4" chamber, and a 3 foot long 2.5" barrel.
I tried shooting it today just with the ball valve, and atleast this time the air was held in, but it didnt deliver much fire power. at 40 psi, the tennis ball went about 10-15, and it was lubricated.
kinda getting frustrated, and im looking for suggestions on a new simple cannon to make. (this is my first cannon)

Actually letting all the air out on the valve at once can sometimes make a valve seal. I have done the same thing on one of my cannons when my sprinkler valve wouldn't seal.

As for you Rayman, I recommend sticking with the sprinkler valve pneumatic. They are relatively simple, and I bet your next valve won't be as quirky.

can you tell me where you put the ball valve before or behind the sprinkler?

i know this sounds stupid but you know that little switch be the soldenoid?

if its flipped up you valve wont seal.

the selonoid was flipped down, and I put the ball valve both infront and behind the sprinkler valve. is there a certain psi I have to get up to?

you could try to stretch the spring to put more pressure on the diaphragm

Take the valve back off the cannon (I assume it is threaded) and hook it up to a garden hose.

Does it work with water? (It was designed to work with water.)

FLush water through it for a while to clean it out.

Now try it with air.

/-/-/-

Does the valve have a vent screw? Is the vent closed?