Pressure change and area ratio help

[sokolomi]

so if you put about 120 psi in a container and then instanly release it into another with something blocking the way, how fast would that escape, what are the variables in this

 

[russ_watters]

Size of the containers and size of the orifice.

 

[sokolomi]

do guys know any good barrel to air container ratios or anything i should know befor i go building a spud gun because i want maximum velocity out of it with like 120 psi

 

[FredGarvin]

Unless you can make a C-D nozzle, you'll probably end up choking the valve on the tank and that will set your max velocity.

 

[russ_watters]

I forgot about choked flow, but in any case, a C-D nozzle still involves choked flow...(i know you know that). If he only cares about mass flow, getting a supersonic airstream doesn't actually do anything for him.