Oxygen Barrier projector
Oxygen Barriers project a dome-shaped bubble filled with breathable 
Oxygen.
The bubble is approximately 27 blocks in radius and 25 blocks high. Its base is two blocks below the base of the Oxygen Barrier device. Players inside the bubble will be constantly supplied with Oxygen. If the player enters the bubble with a drained air tank, it will refill at a rate of 10% per second.
To replenish Oxygen, the Oxygen Barrier must be powered, and there must be an 
Oxygen Generator containing Oxygen Tanks somewhere on the same platform. One tank will be consumed per complete refill.
The Oxygen Barrier does not need to be fully powered to operate. The Oxygen Generator does not need to be powered or supplied with Water to provide oxygen to the barrier, though it needs both to actually make Oxygen Tanks.
Refilling Oxygen using an Oxygen Barrier is 12.5 times more ice-efficient than converting Ice Cubes directly to oxygen with the Oxygen Generator alone, in addition to the hands-free convenience.