If My team is using a SCUBA tank for a t shirt launcher would we just use the first stage regulator or is there a better way to go about this?
We used the standard first stage regulator, followed by a normal first pneumatics regulator which allowed us to change the maximum pressure manually. Be sure to be safe around the tank, if you misuse it, especially in an already odd application, it can become a very dangerous thing.
I just want to further emphasize being very careful around the tank. An 80 cubic foot (10.2 liter) tank at 3000psi has an extreme amount of energy (online figures suggest about as much as a half pound of TNT (or a hand grenade)).
Be very careful when working with the tank, if it drops or falls over and breaks off the valve, all of that energy will be released very rapidly. You will basically have a rocket on your hands that wont stop for people or walls.