# Is a PSA oxygen plant a fire or explosion risk?

**Is a PSA oxygen plant dangerous, and what fire precautions does it need?**

A PSA oxygen plant is not inherently explosive or combustible, according to Open Critical Care, but the oxygen it produces makes fires burn faster and hotter, and guidance asks for ventilation, no ignition sources or smoking nearby, no stored combustibles and fire detection.

## Where the risk comes from

WHO's Foundations of medical oxygen systems (2023) explains that pure oxygen does not burn itself but is an oxidizing agent that makes fires burn faster and hotter than in normal air, and that a fire needs heat or an ignition source, fuel and oxygen. It lists leaks from damaged hoses, flexible pigtails, pipes, valves and poor connections as common causes of oxygen fires and explosions in health facilities, and notes that even a rise in the oxygen level of the air from 21% to 24% can be hazardous. The 2020 WHO interim specification for PSA plants (superseded by WHO's technical specifications of 31 December 2024) warned that oil and grease burn with almost explosive violence when combined with oxygen.

A PSA plant also discharges waste gas. AIGA 113/20, adopted from EIGA Doc 195, notes that the vents are likely to create oxygen-deficient or oxygen-enriched atmospheres around them, and asks for all vents to be directed to a safe location outside buildings, away from people and equipment. WHO (2023) suggests that the nitrogen exhaust should end at least 3 m clear of any door or window that can be opened, or other air intake.

Compressing oxygen adds hazards: AIGA 113/20 notes that oxygen compressor fires typically produce high-velocity oxygen jets containing molten metal, and Open Critical Care says that filling high-pressure cylinders brings additional safety considerations.

## Precautions in the guidance

- No ignition sources: where oxygen is exhausted around the plant, Open Critical Care says there should be no ignition sources, open flames, smoking or sparks. For ULTRAOX plants, the datasheet states that smoking is not allowed on site and that smokers must be at least 10 metres away.
- No combustibles: Global Fund's daily maintenance checklist asks every day whether combustible materials have been removed from in and around the PSA plant. The 2020 WHO interim specification listed room requirements without oil, grease, petroleum-based or other flammable products among the infrastructure requirements the manufacturer had to indicate, and AIGA 113/20 says that storing flammable and combustible materials in buildings housing oxygen 93 systems should be avoided.
- Ventilation and oxygen monitoring: AIGA 113/20 asks for atmospheric oxygen to be monitored and kept between 19.5% and 23.5% where personnel work, and recommends at least six air changes per hour. In Portugal, the ACSS specification ET 03/2006 (revised 2024) asks for ventilation of at least 6 air changes per hour for an oxygen 93 plant. WHO (2023) suggests oxygen depletion sensors in the plant room to monitor the oxygen-enriched atmosphere.
- Fire detection and suppression: AIGA 113/20 asks for rooms with oxygen 93 concentrators and compressors to have fire suppression including smoke detection and sprinklers, firefighting equipment close to the plant, and automatic isolation valves with emergency remote shutdown so that the oxygen sources cannot feed a fire. Global Fund's checklist includes a daily check of the fire detection and suppression system.
- Electrical installation: Open Critical Care says the electrical system must be installed properly and safely; AIGA 113/20 advises avoiding electrical equipment with open or unprotected make-and-break contacts where oxygen enrichment is likely; WHO (2023) notes that LED lighting reduces fire risks.
- Training: Global Fund sustainability guidance (2024) asks for fire safety protocols, and the USAID RISE procedure, written for hospitals in India, for fire safety equipment in place and regular fire safety drills.

## If a fire starts

The USAID RISE procedure says to alert others immediately and to try to suppress the fire only if it is safe to do so, otherwise to evacuate. If it is safe, it lists three steps: close the oxygen outlet valve after the bacteria filter, press the emergency stop on the PSA control panel, and press the air compressor's emergency stop and close its outlet valve.

### Can a PSA plant explode?

Open Critical Care says PSA plants are not inherently explosive or combustible, but oxygen is an accelerant: with an open flame or ignition source, an oxygen-enriched atmosphere can greatly accelerate a fire.

### How far should smokers keep from an ULTRAOX plant?

At least 10 metres, according to the ULTRAOX 2022 datasheet, which also states that smoking is not allowed on site.

## Sources

- [Open Critical Care, Oxygen FAQ: Can you comment on the safety and explosive nature of PSA plants?](https://opencriticalcare.org/faq/can-you-comment-on-the-safety-and-explosive-nature-of-psa-plants/)
- [WHO, Foundations of medical oxygen systems (17 February 2023), sections 2.2.3, 2.2.4 and 3.6](https://www.who.int/publications/i/item/WHO-2019-nCoV-Clinical-Oxygen-2023.1)
- [WHO, Technical specifications for Pressure Swing Adsorption (PSA) oxygen plants, interim guidance (8 June 2020)](https://www.who.int/publications/i/item/WHO-2019-nCoV-PSA_Specifications-2020.1)
- [AIGA 113/20, Safe design and operation of on site generation of oxygen 93% for medicinal use (adopted from EIGA Doc 195), sections 6.2.2, 6.2.3, 6.5, 6.9 and 6.13](https://asiaiga.org/uploaded_docs/en_AIGA_113_20_Generation_of_Oxygen_93_for_Medicinal_Use.pdf)
- [ACSS, ET 03/2006 v.2024 Gases medicinais e aspiração, section 4.2](https://www.acss.min-saude.pt/wp-content/uploads/2016/10/ET-03_2006_v2024-Gases-medicinais_VF.pdf)
- [Global Fund / Build Health International, Daily Maintenance Checklist for PSA plants (Project BOXER)](https://resources.theglobalfund.org/media/xbanfgrc/cr_c19rm-psa-plant-daily-maintenance_checklist_en.pdf)
- [Global Fund / Build Health International, Overview: Sustainability Guidance for PSA Oxygen Plants (22 August 2024)](https://resources.theglobalfund.org/media/bwrp43cm/cr_c19rm-psa-oxygen-plant-sustainability_overview_en.pdf)
- [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)
- [ULTRAOX datasheet 2022, p. 9](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/is-a-psa-oxygen-plant-a-fire-risk/