What should a hospital check when comparing PSA bids?

Flow at the same purity and pressure

A Global Fund briefing note of 3 April 2024 explains that PSA purity falls as more oxygen is drawn from the plant: equipment that gives 20 Nm³/h at 93 ± 3% would give 18 Nm³/h when set to 95 ± 1%. To reach the same flow at 95 ± 1%, the note says, a plant needs larger equipment, with higher operating expenses from its increased power consumption. The 2020 WHO interim specification (superseded by WHO's technical specifications of 31 December 2024) asked for a continuous output flow covering 100% of the oxygen demand at a continuous output pressure of 300 to 600 kPa, and UNDP (2025) says specifications must address flow rate, purity, pressure, energy efficiency and compatibility with existing systems.

Documents and evidence

UNDP's requirements for oxygen plants (REQ-OXY-001, effective 1 January 2025) work as a checklist: official performance test reports for purity, flow and pressure; a letter of authorisation from the manufacturer when the bidder is not the manufacturer; evidence of at least three years of experience with similar projects; the CVs of key personnel for the supplier and local agent; and an electrical requirements chart with starting current, minimum protection current and load curves. The supplier is responsible for checking that its certificates have not expired. The 2020 WHO interim specification asked for a life span of at least 10 years guaranteed by a letter from the manufacturer, not only from the authorised distributor, and for the conformity of the installation to be verified by a certified third party. The certificates themselves are covered in what certificates a PSA supplier should provide.

What each offer covers over the life of the plant

The Global Fund quality assurance policy (amended 15 November 2023) requires a competitive process to obtain best value for money, taking into account total cost of ownership, and WHO's Foundations of medical oxygen systems (2023) says procurement specifications should consider the life cycle and total cost of ownership. The items to compare include:

• Spare parts: the 2020 WHO interim specification asked for, and UNDP asks for, a 3-year spare parts kit listed with part descriptions and costs.
• Maintenance: the 2020 WHO interim specification asked for the costs of preventive and corrective maintenance and spare parts to be set for at least 3 years from installation.
• Warranty: UNDP asks for at least 24 months from commissioning. Global Fund guidance (20 May 2024) says the warranty should state when it begins and expires, which repair costs it covers (parts, shipping, labour, travel) and which wearing or consumable parts it excludes.
• Service: Global Fund service contract guidelines (20 May 2024) say the contract must state whether the labour, travel and accommodation of the service provider's agents are included, and whether service is due by hours of operation, calendar dates or both.
• Energy: PATH and CHAI (2021) put a conventional PSA plant at approximately 1.2 kWh per Nm³ at 65 psig, depending on system efficiency and oxygen service pressure.

Technology and support in the region

A Global Fund note of 4 March 2025 says the most important factor in choosing between PSA, VPSA and VSA is the technology already common and functional in the region, and, where existing plants work well, recommends more plants of the same technology to standardise the tools, skills and expertise needed for maintenance. PATH and CHAI add that, whatever the technology, the tender should include robust technical and performance requirements based on the intended use and location. In UNDP procurements, the GFPHST quality assurance team should carry out the technical and regulatory evaluation of the bids.

Ultra Controlo

The ULTRAOX SC and ULTRAOX ST datasheets state a purity of 94% (±1%).