Why do PSA oxygen plants stop working?

The usual causes

• Power. Global Fund sustainability guidance says reliable power must include properly balanced 3-phase supply, correctly sized cables and protection from voltage fluctuation, plus appropriately sized backup power. Open Critical Care warns that power frequency fluctuation can, over time, damage the large motors, an expensive part of a PSA plant, and advises a small 1 kW UPS for the control circuit and PLC. A USAID operating procedure says not to run the plant when the voltage is unstable.
• Heat and site. PATH notes that the equipment generates substantial heat and needs adequate air conditioning; Global Fund guidance asks for extreme heat and cold to be mitigated and for siting that avoids air pollution and flooding.
• Water in the air. The USAID procedure says never to run the plant if the automatic water drains are faulty or not draining, and the Global Fund daily checklist checks condensate drainage at the compressor, dryer, filters and air tank every day.
• Overdrawing. The USAID procedure warns that drawing more oxygen than the plant's capacity causes a drop in purity and pressure and can lead to malfunction or permanent failure of valves, sensors and gauges.
• Maintenance and spare parts. Global Fund guidance strongly advises a 5-year warranty and maintenance contract and a spare parts inventory for at least two years; PATH adds that a stock of manufacturer-recommended spare parts keeps interruptions short.
• People. Global Fund guidance recommends trained staff on site whenever the plant runs, and daily checklists for early identification of critical malfunctions.
• Money. Running costs include spare parts, scheduled maintenance, repairs, electricity, diesel, distribution and staff salaries, and Global Fund guidance asks for funding to be planned for the plant's life cycle, on average 10 years.

Preventing it

Several of these causes are checked before the plant enters service: the Global Fund commissioning guideline tests backup power against the plant's start-up and running loads, the plant room temperature, the drains and the alarms, and ends with training and a written maintenance plan. After handover, the daily checklist, preventive maintenance at the manufacturer's intervals and a backup supply for outages are there so that a stoppage does not interrupt the oxygen supply to patients. See how a PSA plant is commissioned and what maintenance it needs.

ULTRAOX plants are designed for a minimum life cycle of 150,000 hours, can be connected to a diesel-electric generator, and Ultra Controlo offers preventive maintenance and monitoring through its UltraCare programme.