valve location

[singularity]

im working on a pneumatic cannon and i dont know which would provide better pereformace. heere is a diagram i drew (sorry i cant crop it)

[carlbelcher]

Having the valve closer to your barrel (bottom diagram) will offer slightly better performance, because you will have less dead space.

[CS]

Do as above poster reccomended.

You can crop the photos. Just drag the dot in the lower right hand corner in paint. Im seriously thinking about righting a paint how-to manual for all you noobs! ARG!

[sgort87]

And now for the typical stirring-up of the conversation...

Lately it has been discussed on Spudtech, of the performance INCREASE because of some dead space. It all has to do with heat expansion and such. I'll see if I can find it...

[singularity]

im sorry i have paint shop pro on my othere computer i know how to use that,its kinda sad i dont know how to use ms paint though

so is dead space good or bad?

[carlbelcher]

Well if you ask gort (which I wouldn't ) it might be a good thing, but if you ask most people it's not.

The reason that dead space is not a good thing is that it is empty space that the compressed air coming from you chamber has to fill before it can start to force your projectile out the barrel, there by reducing the pressure and volume of air that is available to fire the projectile.

[sgort87]

I was only throwing that in there. I know that in this case especially, being it a sprinkler valve, dead space must be kept to a minimum.

Put your valve on top irwinner. You want the least ammount of dead space with a sprinkler valve pneumatic.

[LucyInTheSky]

Well GGDT says by increasing the dead space slightly you make the gun better.

[sgort87]

There is a point where it is too far of course.

[frogy]

A valve on the bottom is also easier to use for multiple guns if you must, since I haven't bound another sprinkler valve yet I use the same one on by big pneumatic as on my PB pneumatic and every time I have to change it I have to take out my 1/4" nipple and blow gun so it can clear the chamber since they run parallel...

But if you have the pipe coming out of the chamber long and the pipe after the 2 elbows short, the valve will be behind the chamber so it wont matter...

<img src="http://img170.imageshack.us/img170/6743 ... pespn7.png">

On the top one you have to remove the blowgun or the hose barbs to get the valve off easily...

But the top one can be used if you make the pipe in between the 2 elbows LONG, but that just looks stupid...

[singularity]

why not just have the barrels be removable?

[frogy]

What are you talking about? barrels are always removable in a pneumatic unless it's coaxial, which they are also sometimes removeable...

[singularity]

sorry i got confused when i saw your picture and fow you were talking about removing the valves