Oxygen and PSA
Oxygen 99.5 (medical oxygen, Ph. Eur. 0417)
Oxygen 99.5 is medicinal oxygen with at least 99.5% O2, produced by cryogenic distillation of air: it is the oxygen covered by European Pharmacopoeia monograph 0417 and the Oxygen 99.5% quality of The International Pharmacopoeia (13th edition, 2025).
The International Pharmacopoeia defines medicinal oxygen as Oxygen 93%, Oxygen 98% or Oxygen 99.5%; mixtures of these qualities may be used, but the monograph requirements do not apply to any mixture. The US Pharmacopeia monograph Oxygen sets a lower minimum, not less than 99.0%. WHO interim guidance (2020) notes that cryogenically produced liquid oxygen is always generated off site, not at a medical facility, and NHS England's HTM 02-01 (2026) notes that cylinders supplied by a gas supplier will be above 99% concentration.
ISO 7396-1:2016 states that where all sources of a pipeline system deliver oxygen, the concentration will be greater than 99%, while a supply mixing Oxygen 93 and oxygen sources can vary between 90% and above 99%. A single-stage PSA plant makes Oxygen 93 instead: Ph. Eur. monograph 2455 covers oxygen from a single-stage adsorption plant, HTM 02-01 gives PSA concentrations of up to 95%, and ULTRAOX SC and ST plants deliver 94% (±1%). See Ph. Eur. 0417 and Oxygen 93 vs 99.5%.
Sources
- EDQM, Oxygen (98 per cent) consultation (2020): monographs 0417 and 2455
- EDQM, Ph. Eur. monograph history, Oxygen (93 per cent) 2455
- The International Pharmacopoeia, 13th edition (2025), Medicinal oxygen
- USP-NF, Oxygen
- WHO, Oxygen sources and distribution for COVID-19 treatment centres, interim guidance (4 April 2020)
- NHS England, HTM 02-01 Part A (2026), paragraphs 6.111 and 6.112
- ISO 7396-1:2016, abstract (iso.org)
- ULTRAOX SC datasheet, p. 2
- ULTRAOX ST datasheet, p. 2
Ultra Controlo figures come from its technical datasheets. Third-party facts were read at the source on the date shown.