I belive the O2 chat is re that verminator post. It runs two separate tanks and the gases mix as they inject into the ground. The gases are not mixed in a single tank prior to use.
It's for pest control and not a safe and cheap way to charge airsoft mags. The gas mixture explodes in a porous space like a rodent den. In a pressure vessel like a magazine it would be dangerous, in a 16.4 oz cylinder someone tried to re-charge it would be lethal.