Quote Originally Posted by Max
I know the rules say that you must have an on/off valve on your main tank and a dump valve both reachable from out of the robot but would it be allowed to just have a ball valve connected to the tank which vents all gas downstream of itself?
The on/off valve on the main tank, or the isolation valve if you use pin-valved main tanks, have the job to keep the weapon gas-less untill activation is called by the arena marchal or ringmaster.
The dump valve has to vent the complete system.

And also could you have it so that the valve needs a flathead screwdriver to turn it on and off from outside the robot?
Preferably no tools for activation or dump. And a flathead screwdriver is the last tool I would suggest for such application.
Allen key,Torx or socket wrench, yes. Philipshead or Pozidriv crosshead screwdriver, if nothing else is available. Flathead, no.