# How is a PSA oxygen plant protected from dust?

**How is a PSA oxygen plant protected from dust and polluted air at its site and air intake?**

Guidance protects a PSA plant from dust with a covered housing that keeps out precipitation, wind and dust, an air intake sited away from pollution sources, and filters on the intake and compressed air that operators check daily; WHO (2023) also asks for site dust conditions to be addressed in the design.

WHO's Foundations of medical oxygen systems (2023) asks for site conditions such as elevation, temperature, humidity and dust to be addressed at the design phase, and says the oxygen production system must be located under a covered structure that protects it from precipitation, wind or dust. Assist International, answering on Open Critical Care, lists how dusty and how hot the area is among the local factors to weigh when preparing a PSA plant site.

## The housing

- Enclosure: the medicinal gas room must be protected from precipitation, wind or dust, external mechanical damage and unauthorised personnel (WHO, 2023).
- Openings and finishes: WHO suggests grids or nets in openings such as windows to keep the room as clean as possible, with finishes that are easy to clean and kept dust free.
- Containers: Global Fund guidance on site readiness (11 April 2025) asks for a canopy that protects a containerised plant from direct weather.
- Spare parts: WHO (2023) notes that dust and other environmental conditions can damage the useful life of stored parts, even those that do not expire.

## The air intake

AIGA 113/20, adopted from EIGA Doc 195, says that since air is the raw material of the supply system, its quality, including contamination with particulate matter, is probably the major concern in selecting a site. It asks for the plant to be installed where the risk of intake contamination from engine exhaust, ventilation and vacuum system discharges and scavenging systems is minimised, for the compressor suction never to be near such sources, and for site surveys over a significant area around the proposed location.

Global Fund guidance asks for air pollutants such as generator exhausts, idling cars and waste incinerators to be at least 10 m from a PSA plant, and its commissioning guidelines (28 August 2024) check that the plant housing is at least 10 m from fire ignition and pollution sources. WHO (2023) adds that nearby contaminated air, such as diesel generator exhaust or a waste incinerator, may affect performance, and that the distances endorsed by the manufacturer should be followed to aid oxygen quality and reduce degradation of parts such as filters and sieve beds.

## Filters and daily checks

- Filters: WHO's interim PSA specifications (8 June 2020, superseded by WHO's technical specifications of 31 December 2024) asked for a pre-filter (>5 micron), a coalescing filter (0.1 micron) and a coal or activated carbon filter, and listed ISO 5011, on inlet air cleaning equipment for compressors, among the product standards. A USAID RISE operating procedure, written for hospitals in India, describes pre-filters and carbon, fine and bacterial filters removing dust, dirt and other foreign material.
- Daily checks: the Global Fund daily maintenance checklist (Project BOXER) asks whether the air intake filter mats, intake cover and ventilation filters are in place and whether the floor and surfaces have been mopped and dusted.
- Troubleshooting: the USAID procedure lists an obstruction to the air flow near the compressor and dirty pre-filters among the checks when oxygen tank pressure is low.

For ULTRAOX plants, the 2022 datasheet asks for ambient air reasonably free from dust, at an acceptable level of humidity and free from chemical contamination, with smokers at least 10 metres from the plant. The ULTRASCREW compressors have a high efficiency suction air filter, and the compressed air passes a water separator with electronic drain, high efficiency micro and sub-micro filters and an activated carbon filter. According to the same datasheet, Ultra Controlo oxygen systems are installed in extreme locations such as deserts, islands, Patagonia and Amazonia.

### How far should a PSA plant be from a generator exhaust?

Global Fund site-readiness guidance (2025) asks for air pollutants such as generator exhausts, idling cars and waste incinerators to be at least 10 m from a PSA plant.

### Can dust affect the sieve beds?

WHO (2023) says contaminated air near the plant may affect performance and that the manufacturer's distances should be followed to reduce degradation of parts such as filters and sieve beds.

## Sources

- [WHO, Foundations of medical oxygen systems (17 February 2023), sections 2.2.1, 2.2.4, 3.4.3, 3.5.1 and 3.5.2](https://www.who.int/publications/i/item/WHO-2019-nCoV-Clinical-Oxygen-2023.1)
- [Open Critical Care FAQ (Assist International): PSA plant site preparation, containers versus a built room](https://opencriticalcare.org/faq/what-are-key-considerations-for-psa-plant-site-preparation-and-what-is-the-advantage-versus-disadvantage-of-installing-psa-in-containers-instead-of-a-room-built-for-it/)
- [AIGA 113/20 (adopted from EIGA Doc 195), On site generation of oxygen 93% for medicinal use, section 6.2.1](https://asiaiga.org/uploaded_docs/en_AIGA_113_20_Generation_of_Oxygen_93_for_Medicinal_Use.pdf)
- [Global Fund / Build Health International, Overview: PSA Plant Site Readiness Process and Responsibilities (11 April 2025)](https://resources.theglobalfund.org/media/tkyd3gwi/cr_c19rm-psa-plant-site-readiness-process-responsibilities_steps_en.pdf)
- [Global Fund / Build Health International, Overview: PSA Oxygen Plant Commissioning Guidelines (28 August 2024)](https://resources.theglobalfund.org/media/qp3h1vxo/cr_c19rm-psa-oxygen-plant-commissioning_overview_en.pdf)
- [WHO, Technical specifications for PSA oxygen plants, interim guidance (8 June 2020)](https://www.who.int/publications/i/item/WHO-2019-nCoV-PSA_Specifications-2020.1)
- [USAID RISE, Standard Operating Procedures: PSA Plant Operations and Preventive Maintenance by the Facility Management](https://media.path.org/documents/SOP_on_PSA_Plant_USAID_RISE_04032022_F7fUBr6.pdf)
- [Global Fund / Build Health International, PSA plant Daily Maintenance Checklist (Project BOXER)](https://resources.theglobalfund.org/media/xbanfgrc/cr_c19rm-psa-plant-daily-maintenance_checklist_en.pdf)
- [ULTRAOX datasheet 2022, p. 9, p. 10, p. 16 and p. 19](https://www.ultracontrolo.com/ultraox)
- [WHO, Technical specifications for health facility based medical oxygen systems (31 December 2024), note on the oxygen generator plant specification (supersedes the 2020 interim PSA specifications)](https://iris.who.int/server/api/core/bitstreams/ff437601-add3-44c8-8149-b85f0cdb2b52/content)

Reviewed: 2026-10-22. Ultra Controlo engineering. https://library.ultracontrolo.com/answers/how-is-a-psa-plant-protected-from-dust/