There is no breathable air in either space or hyperspace. When powered, Air Generators will attempt to fill the space around them with breathable air. If the room they are in has a hole the Air Generator will continue to try and fill open space outside of the hole (unsuccessfully), but the hole will not drain the room of air.
Air Canisters can be filled by right clicking them on a powered Air Generator.
It uses accepts EU or RF power on any side. It does not keep its power stored when broken.