Where does oxygen in hospital tanks comes from?

Medical and industrial oxygen is typically made by liquefying and fractionating air which is 21% oxygen. Gas suppliers then ship the oxygen either in liquid form or as compressed gas in pressure cylinders.

Hospitals typically have large liquid oxygen tanks which provide all the gaseous oxygen to the wall outlets via pipes.

Additionally, there are pressure tanks of gaseous oxygen for portable and emergency use.

However, there is some growth in molecular sieve technologies which can allow hospitals to filter nearly pure oxygen directly from the air.