# Can a PSA oxygen plant be expanded later?

**Can a PSA oxygen plant be expanded when the hospital grows, without replacing it?**

A PSA oxygen plant can be expanded later: the Open Critical Care encyclopedia lists "easily scalable" among the advantages of PSA plants, the ULTRAOX ST datasheet states that the plant is expandable without replacing the concentrator, and the ULTRAOX SC is built with a modular design that increases flow capacity progressively.

The Open Critical Care encyclopedia entry on PSA plants, based on PAHO recommendations, lists "easily scalable" among their advantages.

## When to expand

Global Fund sustainability guidance (August 2024) says need should not be estimated by current demand, and asks for oxygen production to be compared with consumption every year. If the plant is being overused, it suggests procuring additional methods of oxygen production, as secondary or tertiary sources, to supplement the existing plant; if it is underused, extending the pipeline or the cylinder distribution to peripheral facilities. UNDP's 2025 requirements for oxygen plants include future expansion plans in the demand assessment.

## What has to keep up with the plant

- Pipeline: NHS England's HTM 02-01 (2026) sizes pipes to keep the pressure loss below 5% of the nominal pipeline pressure and, where many beds need CPAP, suggests increasing the size of the flow loop supply pipeline or running a separate pipeline from the source.
- Standby compressors: HTM 02-01 asks for a duplex compressor arrangement and, where more than two compressors are installed, for the design flow to be delivered with one compressor out of service.
- Backup sources: HTM 02-01 sets the types, capacities and locations of primary, secondary and tertiary sources from the system design parameters and a risk assessment. See what backup to keep with a PSA plant.
- Power: Global Fund commissioning guidelines check that backup power meets the start-up and running loads of the plant equipment.

## ULTRAOX plants

ULTRAOX SC and ST plants can be built according to the physical space available. The ULTRAOX SC datasheet states that the plant is constructed with a modular design and increases its flow capacity progressively, with no need for a total back-up compressor, and lists "expandable without need of replacement" among the advantages of its container version. The ULTRAOX ST datasheet states that the plant is expandable without the need to replace the concentrator. In both, compressors switch and generators start in cascade to keep the oxygen supply continuous. The ULTRAOX ST table runs from 0.32 to 164 m³/h per unit; see [what capacities ULTRAOX plants cover](https://library.ultracontrolo.com/answers/ultraox-capacity-range/).

### Should a new PSA plant be sized above today's demand?

Global Fund guidance says need should not be estimated by current demand, and WHO (2023) notes that PSA plants are sized on peak flows.

### What if the plant turns out to be underused?

Global Fund guidance suggests extending the medical gas pipeline or expanding cylinder distribution to peripheral healthcare facilities.

## Sources

- [Open Critical Care, O2 Encyclopedia: PSA Plant (based on PAHO recommendations)](https://opencriticalcare.org/wp-content/uploads/2022/05/PSA-Plant.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)
- [UNDP, REQ-OXY-001 v01, Technical and regulatory requirements for oxygen plants (effective 1 January 2025), section 7](https://healthimplementation.undp.org/wp-content/uploads/2025/01/REQ-OXY-001-v01-UNDP-TECHNICAL-REGULATORY-REQUIREMENTS-FOR-OXYGEN-PLANTS.pdf)
- [NHS England, HTM 02-01 Part A (2026), paragraphs 2.27, 4.47, 4.58 and 6.116](https://www.england.nhs.uk/wp-content/uploads/2016/05/health-technical-memorandum-02-01-medical-gas-pipeline-systems-part-a-design-installation-validation-verification-aug-2026.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, Foundations of medical oxygen systems (17 February 2023), section 2.10.1](https://iris.who.int/server/api/core/bitstreams/4ad6f5fd-089e-4142-8439-b64e98d816d8/content)
- [ULTRAOX SC datasheet, p. 2 and p. 4](https://www.ultracontrolo.com/products/ultraox)
- [ULTRAOX ST datasheet, p. 2, p. 4 and p. 5 (model table)](https://www.ultracontrolo.com/products/ultraox-st)

Reviewed: 2026-10-22. Ultra Controlo engineering. https://library.ultracontrolo.com/answers/can-a-psa-plant-be-expanded-later/