# Which parts of a PSA plant must be oxygen-compatible?

**Which components of a PSA oxygen plant must meet oxygen compatibility requirements such as ISO 15001, and why?**

In UNDP procurement, REQ-OXY-001 (effective 1 January 2025) requires all PSA plant components apart from the piping system to comply with ISO 15001 and be cleaned to ASTM G93; WHO's 2024 specifications ask for oxygen-compatible piping within and downstream of the generator and an entire system cleaned for oxygen-enriched use.

## What buyers' documents ask for

- UNDP REQ-OXY-001 (version V01), section 5.1: apart from the piping system, all components of the PSA plant must comply with ISO 15001 and be cleaned in accordance with ASTM G93 to ensure oxygen compatibility. In its Table 1, the row for medical-grade copper pipe lists ISO 7396-1 and EN 13348.
- WHO, Technical specifications for health facility based medical oxygen systems (31 December 2024), oxygen generator plants: piping and hoses compatible for use with oxygen according to ISO 15001, or equivalent, for any piping within and downstream of the oxygen generator, and the entire system cleaned for use in oxygen-enriched environments (for example to ISO 15001 or equivalent), with no more than 550 mg/m2 of hydrocarbon contamination.
- WHO (2024), cylinder filling stations fed by an on-site plant: oxygen-compatible piping to and from the booster compressor up to the manifold header, a reciprocating booster with an oil-free oxygen side, and cleaning to no more than 220 mg/m2 of hydrocarbon contamination and no particulates larger than 100 microns.
- The earlier WHO interim specification for PSA plants (8 June 2020) asked for all pressurised vessels to be cleaned according to ISO 15001, ASTM G93 or equivalent. That interim guidance stated that it would expire 2 years after publication, and the 2024 specification for oxygen generator plants supersedes it.

## What the industry guidance says

AIGA 113/20, adopted from EIGA Doc 195, asks for materials of construction to be selected according to existing codes and standards for compatibility with oxygen for medicinal use, depending on the service pressure and gas velocity at each step of the process (section 6.3). Non-metallic materials, including gaskets, valve packing and compressor piston rings, shall be compatible with oxygen service, taking into account the risk of toxic products being released in case of combustion or overheating. Lubricants likely to be in contact with oxygen shall be compatible with oxygen, and all materials potentially in contact with oxygen shall be cleaned for oxygen service according to AIGA 012 (section 6.4).

## Why

ISO 15001:2010 covers materials, components and devices for anaesthetic and respiratory applications that can come into contact with oxygen, in normal condition or single fault condition, at gas pressures greater than 50 kPa. The aspects it addresses are cleanliness, resistance to ignition and the toxicity of products of combustion or decomposition, at the design, manufacturing, maintenance and disposal stages; its examples include medical gas pipeline systems, pressure regulators and flexible connections.

For oxygen compression, AIGA 113/20 (section 6.13) lists ignition caused by mechanical friction, particle impingement and adiabatic compression, with possible consequences of a loss of containment, the projection of molten metal at high pressure and the release of a toxic combustion by-product. Among the mitigations, it names the correct selection of materials used within the compressor, including non-metallic materials, cleaning agents and lubricating oils. For filling stations, see what a high-pressure oxygen booster is.

## Upstream of the adsorbers

On the compressed air side, AIGA 113/20 (section 6.12) asks for a drying and filtration system downstream of the air compressors to deliver dry and oil-free air at the inlet of the adsorber vessels, and says that food grade lubricants and oils should be used wherever possible. In UNDP's Table 1, the row for the medical air compressor and dryer lists ISO 7396-1, ISO 12500-4 and ISO 8573-1. See [what air treatment a PSA plant needs](https://library.ultracontrolo.com/answers/what-air-treatment-does-a-psa-plant-need/).

## On ULTRAOX plants

The ULTRAOX datasheet (2022, p. 4) states that all parts in contact with oxygen are non-ferrous, preventing iron oxidation.

### Which cleaning standards do UNDP and WHO cite for oxygen plants?

UNDP's REQ-OXY-001 cites ASTM G93; WHO's 2024 specifications cite ISO 15001 or equivalent, with a hydrocarbon contamination limit of 550 mg/m2 for generator plants and 220 mg/m2 for filling stations.

### Why do gaskets and seals need to be oxygen-compatible?

AIGA 113/20 asks for non-metallic materials, including gaskets, valve packing and compressor piston rings, to be compatible with oxygen service, taking into account the risk of toxic products if they burn or overheat.

## Sources

- [UNDP, REQ-OXY-001 V01, Technical & Regulatory Requirements for Oxygen Plants (effective 1 January 2025), section 5.1 and Table 1](https://healthimplementation.undp.org/wp-content/uploads/2025/01/REQ-OXY-001-v01-UNDP-TECHNICAL-REGULATORY-REQUIREMENTS-FOR-OXYGEN-PLANTS.pdf)
- [WHO, Technical specifications for health facility based medical oxygen systems (31 December 2024), sections 1.1 and 1.2, rows 18 and 31](https://iris.who.int/server/api/core/bitstreams/ff437601-add3-44c8-8149-b85f0cdb2b52/content)
- [WHO, Technical specifications for PSA oxygen plants, interim guidance (8 June 2020)](https://iris.who.int/server/api/core/bitstreams/d53996d5-380c-44ae-9fe8-9e529d3270cd/content)
- [AIGA 113/20 (adopted from EIGA Doc 195), On site generation of oxygen 93% for medicinal use, sections 6.3, 6.4, 6.12 and 6.13](https://asiaiga.org/uploaded_docs/en_AIGA_113_20_Generation_of_Oxygen_93_for_Medicinal_Use.pdf)
- [ISO 15001:2010, Anaesthetic and respiratory equipment: Compatibility with oxygen, abstract (iso.org)](https://www.iso.org/standard/44250.html)
- [ULTRAOX datasheet 2022, p. 4](https://www.ultracontrolo.com/ultraox)

Reviewed: 2026-10-23. Ultra Controlo engineering. https://library.ultracontrolo.com/answers/which-parts-of-a-psa-plant-must-be-oxygen-compatible/