Hospital Oxygen Consumption Calculation and Plant Sizing

Start with the bed schedule and clinical profile

List every area that draws oxygen: general wards, high-dependency and intensive care beds, operating theatres, recovery, emergency, delivery, neonatal and diagnostic areas. For each, record the number of beds or outlets and the likely proportion of patients needing oxygen.

Demand per bed varies widely. A general ward patient on low-flow oxygen draws a few litres per minute, while a ventilated intensive care patient can draw considerably more, and peaks occur during procedures. Use design assumptions agreed with the clinical team and, where possible, the figures required by the design standard in force for your project.

Remember that a seasonal or epidemic rise in respiratory cases can change the proportion of patients on oxygen. Ask the clinical team for a realistic worst case rather than only the average.

From connected flow to design flow

Multiply the number of outlets by the flow assumed per outlet to obtain the connected flow, then apply a diversity factor, because not every outlet is used at full flow at the same time. Diversity factors differ by area type and are normally set by the design standard or consultant; do not guess them.

Separate average demand from peak demand. The pipeline must be sized for peak, while consumption over time determines cylinder or liquid storage. For a hospital that is growing, also add allowance for planned expansion and, in a health emergency, surge capacity.

• Connected flow per area and total
• Diversity factor agreed with the consultant
• Peak flow for pipeline and plant
• Average daily consumption for storage
• Allowance for expansion and surge

Oxygen plant capacity calculation and concentrator output

Plant output is usually expressed in cubic metres per hour or litres per minute. One normal cubic metre per hour is roughly 16.7 litres per minute, so a rating of 3 Nm³/h is around 50 litres per minute and 48 Nm³/h is around 800 litres per minute. This conversion answers the common question of how many litres an oxygen concentrator plant provides.

The MIL's oxygen concentrators use molecular sieves to produce 93-95% oxygen-enriched air and come in six sizes from 3 to 48 Nm³/h of O₂. Choose a size, or a combination of units, so that the plant can meet the design peak with a unit out of service. For the purity question see oxygen 93% vs 99% medical oxygen.

Buffer storage, redundancy and backup

A PSA plant delivers a steady output, so a buffer vessel helps cover short peaks. Size it from the difference between peak demand and plant output over the expected peak duration, as well as the plant's response and start-up behaviour. Compressors, dryers and filters feeding the plant need their own redundancy.

Backup supply, such as a cylinder manifold or a liquid source, should cover the time needed to restore the plant, with automatic changeover and alarm signalling. Discuss the options with the consultant and read hospital oxygen supply sources for a comparison.

Checks, assumptions and next steps

Document all assumptions: bed numbers, flows, diversity, safety margins and operating hours. Review the results with the clinical team, then check that the pipeline diameters and source configuration match the calculation. Also confirm site conditions such as air quality, ambient temperature and power for the plant.

Beckfinity can provide product data for MZ Liberec oxygen concentrators to support your calculation. Share your bed schedule with our specialists for a technical consultation; final design remains the responsibility of your consultant.