SpudFiles

well the pic is pretty self explanatory, but what my plan is to make an small air cannon with a 1.5in barrel and a 3in chamber in a coaxial setup. it will be diaphram valve piloted by a modded sprinkler.all of the internals will be hidden under a larger di tube. i've been showing this to my dad, he doesn't think it will work. i want to hear for you guys wether or not it will work so pls tell me what you think.

looks fine in concept, but how are you going to hold the diaphragm in?

the 3in endcap witch connects to the sprinkler valve right behind the diaphram.

Looks like it has potentual. When does the building begin? 8)

well i dont think that will work, because most people make their diaphragm so that it can be replaced but your design makes it permanent and that means that you have to get it right the first time.

sandman wrote:well i dont think that will work, because most people make their diaphragm so that it can be replaced but your design makes it permanent and that means that you have to get it right the first time.

Anyway what you are saying is that it wil work the first couple of times until something will happen and he could not do a thing due to it being permanent.
Anyway good lob i think it will work

that is if he does it right

im trying to think of a way to unscrew the back end entirely maby if i put a female connector on the front halve of the 25in mark and a male on the other.

somthing like this
it could also be used for breach loading

my suggestion is to use a union to hold the diaphragm in place, and this will also make it serviceable.

im sorry this is very noobish, but what is a union?
nm just looked it up on the wiki. good idia

that is a union, by unscrewing the middle both sides come off

A union would be a good option for servicability but a 3" one wouldn't exactly be cheap either.

im attempting to find online sources for pvc pipes because my 3 local hardware stores dont have any 3in pipe that can take pressure. any suggestions?

Try http://www.mcmaster.com/