# What is a PSA medical oxygen generator?

A PSA (pressure swing adsorption) oxygen generator makes medical oxygen on site from ambient air, which is about 21% oxygen and 78% nitrogen.

Compressed, filtered and dried air flows into a column of zeolite molecular sieve that holds back nitrogen under pressure, so oxygen-rich gas passes on to a buffer tank. Two columns take turns: while one produces oxygen, the other depressurises and releases its nitrogen, so the supply does not stop. Ultra Controlo PSA plants are called ULTRAOX; each is built around ULTRACON oxygen concentrators with two molecular sieve columns.

## Sources

- [Ultra Controlo, Medical gas answers: ULTRACON datasheet; ULTRAOX page.](https://www.ultracontrolo.com/medical-gas-answers#what-is-a-psa-oxygen-generator)
- [ultracontrolo.com: ULTRAOX](https://www.ultracontrolo.com/ultraox)
- [ultracontrolo.com: PSA oxygen guide](https://www.ultracontrolo.com/psa-medical-oxygen-generator-for-hospitals)

Reviewed: 2026-10-22. Ultra Controlo engineering. https://library.ultracontrolo.com/answers/what-is-a-psa-oxygen-generator/