Oxygen Concentrator: How Does It Work, and What Limits Its Purity and Output?

The principle: pressure swing adsorption

Air is about 78% nitrogen, 21% oxygen and 1% argon and other gases. A concentrator compresses air and passes it through a vessel filled with zeolite, a porous mineral that adsorbs nitrogen more strongly than oxygen at higher pressure. Oxygen passes through the bed and is collected, while nitrogen stays trapped in the sieve.

When the bed is saturated, pressure is released and the nitrogen is desorbed and vented. Two or more beds work in alternation so that one is producing while the other is regenerating, which gives a continuous oxygen stream.

Parts of a hospital oxygen plant

MZ Liberec's MIL's concentrators are built on molecular sieves that separate nitrogen from oxygen by molecule size and provide 93–95% oxygen-enriched air in six sizes, from 3 to 48 Nm³/h of O₂. According to the manufacturer, this gas may replace medical oxygen provided all required parameters are met. See the MIL's oxygen concentrators.

• Air compressor with filters and dryer, because the sieve needs clean, dry, oil-free air.
• Air receiver to buffer the compressor output.
• Two or more adsorber towers with molecular sieve and switching valves.
• Oxygen buffer tank to smooth flow and pressure.
• Control cabinet with oxygen analyser, alarms and automatic changeover to reserve supply.
• Optional booster and cylinder filling station.

Why purity tops out near 93–95%

Air contains about 0.9% argon, which behaves similarly to oxygen on a zeolite sieve and passes through with it. For this reason standard PSA plants reach a practical limit around 93–95% oxygen, with the balance mainly argon and a little nitrogen. Higher purities require different technology or a further stage.

Whether 93% oxygen is acceptable depends on pharmacopoeia, local requirements and the clinical use; see 93% versus 99% medical oxygen. Always confirm with your clinical and regulatory team.

What limits output

Output depends on the size of the sieve beds, the quality and volume of feed air, ambient temperature and altitude, and the age of the sieve. High humidity, oil contamination or dust shorten sieve life. Plants are rated at specified inlet conditions, so ask what rating applies in the UAE summer.

Maintenance of dryers, filters and compressors is therefore central to keeping capacity. Plan service with oxygen concentrator plant maintenance.

Oxygen concentrator versus oxygen generator

In hospital practice the terms are often used interchangeably, but there are differences in scale. A concentrator usually means a self-contained device for one or a few patients, while an oxygen generator or plant produces tens of cubic metres per hour for a pipeline. Both use the same PSA principle, but a plant adds receivers, analysers, redundancy and a reserve source.

For site planning and comparisons with cylinders and liquid oxygen, read how hospitals get oxygen and the cost view in concentrator plant cost factors.

Selecting a plant

Start from demand: bed numbers, ventilator use and diversity. Add a reserve supply and decide on plant-room conditions. UAE regulation of devices and facilities is set by authorities such as MOHAP, DHA and DOH, so check current requirements before ordering.

Beckfinity can help you size a concentrator plant from MZ Liberec; request a consultation with your room list.