This thread was originally in the “Ask the Vex Staff” page, and I thought it would be more helpful if posted here.
Most of your answers and a labeled diagram can be found in the vex wiki article about "Pneumatics Kit 2.
The listed spec for inflating the pneumatics is 100 psi, but that is impossible to enforce. I can say that my team has gone over 200 psi with no explosions or leaks, but I won’t recommend doing that.
I’m sure other people have entertaining experiences about “things not to do.”
The max pressure that is recommended for the pneumatics is 250 psi, although most bike pumps don’t have gauges that go over 160 psi. Also, as the above person mentioned, in competition the pneumatics should not exceed 100 psi. As for things not to do: don’t try to pull out the tubing without pushing in the ring things. Other than that its pretty hard to screw anything up if you follow the directions.
To add on to PSI limits, you are NOT allowed to go above 100 PSI, and is considered competition illegal to do so (even though it is technically safe to go above). See this thread.
No, it is not – you may damage your pistons.
Everyone looks at the tank and sees “200psi! It must be safe to fill it up that much.”
However, the pistons are actually the limiting factor for the system. This is the spec sheet for the NCJ2D10-200 cylinder from the manufacturer’s website: http://content.smcetech.com/pdf/ncj2.pdf
It says the “maximum operating pressure” for the cylinder is 100psi.
Summary: Don’t fill past 100psi.
//Andrew
I’m glad someone linked to this.
ya I just found it and was gonna link it as well.
ya, but I beat you, and that’s all that matters! haha. 
(<- kidding)
Kidding aside–it’s a good idea to look at the spec sheet before making any claims about safety.
Ya when I looked into getting another reservoir I saw the piston page and was surprised.