I need to know if it’s legal to use a CO2 gas system to power the scoop on a 3kg sumo. 
sounds intruiging, but i cant help ya 
Jim,
We have a rule that may apply:
"3. The robot will not include a device that insufflates any liquid, powder, or gas. "
I had to look up “insufflate”, too. If the C02 is never vented (i.e. a one shot flipper) then there would be no problem.
If you are thinking of multiple flips, then I assume that the C02 must be vented somewhere. That would be a call that the judges would have to make. It would be best to get a clarification before the event.
Rick Brooks“insufflate” Yup, nothing like keeping an odd word from the original poor translation of the Japanese rules.
In context, “insufflate” (when knowing the history of the Japanese Rules) means your robot can not blow, eject, direct, focuse any liquid, gas, or powder at your opponent. Also, this can not be done to leave any residue on the Dohyo.
So it really comes down to using the definition of the word in or out of context in how it is used.
But the local officials of the event really defines the word. The Robothon still uses that word, but will allow pneumatic actuated lifting devices because it is not in violation of the historical context.
Pete