# Scroll compressor

A scroll compressor compresses air between two interleaved spiral scrolls, one fixed and one orbiting, which trap pockets of air and shrink them towards the centre; oil-free scroll designs put no oil into the air they compress.

Oil-free scroll compressors suit medical air because no compressor oil can reach the pipeline. The EDQM history of Ph. Eur. monograph 1238, Air, medicinal, notes that its oil test is relevant only when an oil-lubricated compressor is used.

ULTRACECO SC is the oil-less scroll compressor range from Ultra Controlo: compression is exempt of oil or grease, inlet filtration goes down to 1 micron, and a configuration can grow from one skid to eight skids under one QuAir PLC controller. ULTRAAR SC medical air plants, built to EN ISO 7396-1, use these totally oil-free scroll (spiral) compressors, and Ultra Controlo describes its oil-less ULTRACECO compressors as [Class 0](https://library.ultracontrolo.com/glossary/class-0/) under ISO 8573-1. The larger ULTRACECO SCR range is a two-stage rotary design, not a scroll.

## Sources

- [EDQM, Ph. Eur. monograph 1238 Air, medicinal: history (oil test)](https://extranet.edqm.eu/4DLink1/Web_mono_hist?1238)
- [ULTRACECO SC datasheet, p. 2 and p. 3](https://www.ultracontrolo.com/products/ultraceco-sc)
- [ULTRACECO SCR datasheet, p. 2](https://www.ultracontrolo.com/products/ultraceco-scr)
- [ULTRAAR SC datasheet, p. 2 and p. 3](https://www.ultracontrolo.com/products/ultraar-sc)
- [Ultra Controlo, Medical gas answers: oil-free vs oil-lubricated medical air; glossary, Class 0](https://www.ultracontrolo.com/medical-gas-answers#term-class-0)

Reviewed: 2026-10-22. Ultra Controlo engineering. https://library.ultracontrolo.com/glossary/scroll-compressor/