RE: psi vs. fps [TANKS]

["Steve Tyng" <STyng-at-ACPTrust.com>]

Chris wrote:

> Is there an easy way to calculate how much velocity one would 
> get by knowing the psi?

You would need to know the volume of your accumulator, length of the
barrel, and flow characteristics of your trigger valve.

> In the case of those solenoids Gary 
> recommended for the rocket system 
> (http://www.surpluscenter.com/item.asp?UID=2006062119193174&item=20
> -1138&catname=air) will I still get 200-300 fps with the 150 
> psi rating?

The gas valves in paintball markers are designed to provide a large flow
of gas all at once to push the paintball down the barrel.  Most
pneumatic solenoid valves that I have seen usually have a relatively
small orifice.  I don't know if these valves would provide the "oomph"
required to get any decent velocity.  This can be overcome by using a
restrictor device to keep the paintball from traveling down the barrel
until a sufficient amount of pressure has built up behind it.  This is
usually an o-ring with a slightly smaller inside diameter than the
paintball.  In effect you are turning the paintball itself into a
pressure relief valve.  This is what Frank had tried on his prototype
homebuilt marker.  This is also how the warship guys build their CO2 bb
cannons.  


Steve Tyng