piston or sprinkler valve?

[aussiecyclist]

hey guys, working atm on a second punamic. wanting to fire coke cans and bottles of 600ml capacity. meraning the barrell would be 65mm dia. would you think that a piston or a modde sprtinkler valve be recomended for this use. the connon would be in a "mortor" set up.

[saladtossser]

piston

good for large guns

[boilingleadbath]

Well, let's put it this way:
A 24mm sprinkler valve (acctualy, that's about right for all the sprinklers, regardless of size) flows at approximatly 30% of ideal for a 24mm oppening.
On the other hand, a 65mm diaphram valve will flow at about 50% of ideal for it's 65mm porting... giving it about 12 times the flow.

The muzzle energies of a 150cm long barrel-ed launcher at (that's what? 7 bar?) are 670J and 2100J for the sprinkler valve and diaphram/piston valve, respectivly (47 and 80some meters/sec)... you make the call.