Oxygen and PSA
How many litres per minute of oxygen per hospital bed?
How many litres per minute of oxygen should be planned per hospital bed, ICU bed and theatre?
Short answer
NHS England's HTM 02-01 (2026) gives wards a design flow of 10 L/min per terminal unit (typical use 6 L/min), plans critical care at 60 L/min per bed space where high-flow ventilation is used (10 L/min without), and theatres at 50 L/min for the first operating room plus 10 L/min for each other.
HTM 02-01 states that pipeline flow cannot be predicted precisely, but gives guideline flows that have proved adequate in practice. It sets a design flow for each terminal unit and, for each department, a diversified flow Q calculated from the number of beds, treatment spaces or rooms in use, not from the number of terminal units. A critical care bed space, for example, may have four or more oxygen terminal units.
| Area | Design flow per terminal unit | Typical flow | Planning basis in HTM 02-01 |
|---|---|---|---|
| In-patient accommodation | 10 L/min | 6 L/min | Use of NIV, BiPAP and CPAP is taken into account with the high-flow ventilation calculations |
| Critical care units | 60 L/min | 15 L/min | All bed spaces assumed occupied and using oxygen; Q = 60 L/min per bed space with high-flow ventilation, 10 L/min without; each terminal unit able to deliver 100 L/min |
| Operating suites | 50 L/min | 20 L/min | Q = 50 L/min for the first operating room and 10 L/min for each of the others; each terminal unit in operating and anaesthetic rooms able to pass 100 L/min |
Other figures in use
- Portugal: the ACSS specification ET 03/2006 (revised 2024) recommends that all intensive care and emergency observation beds can deliver high-flow oxygen up to 60 L/min, and that 20% of inpatient beds can do the same.
- COVID-19 treatment centres: WHO's interim guidance of 4 April 2020 used an average of 10 L/min per severe and 30 L/min per critical COVID-19 patient, in a sample plan for a 100-bed facility. WHO notes that the sample is based on a patient count, and that typical quantification would be based on the equipment available.
- Patient devices: WHO's Foundations of medical oxygen systems (2023) lists 1 to 5 L/min for a nasal cannula and 10 to 60 L/min for high-flow nasal oxygen.
From beds to plant size
HTM 02-01 sizes the supply line from the plant to the distribution system for the full design flow of the system plus 25%, and notes that PSA regeneration uses a proportion of the product gas, which should be taken into account when sizing the plant. To compare a total in litres per minute with plant capacities, WHO's 2020 interim guidance multiplies by 60 to get litres per hour and divides by 1,000 to get m³/h. ULTRAOX ST models range from 0.32 to 164 m³/h per unit. See also how to estimate a hospital's oxygen demand.
More questions
Is the flow per bed the same as the flow per outlet?
No. HTM 02-01 gives design flows per terminal unit, but calculates diversified flows from the number of beds, treatment spaces or rooms, and a critical care bed space may have four or more oxygen terminal units.
Is 60 L/min per ICU bed always needed?
No. HTM 02-01 (2026) reduces it to 10 L/min per bed space where there is no requirement for high-flow ventilation.
Sources
- NHS England, HTM 02-01 Part A (2026), paragraphs 4.6, 4.13, 4.45, 4.49 to 4.51, 4.54, 6.110 and Table 2
- ACSS, ET 03/2006 v.2024 Gases medicinais e aspiração, section 6.7
- WHO, Oxygen sources and distribution for COVID-19 treatment centres, interim guidance (4 April 2020), Table 1
- WHO, Foundations of medical oxygen systems (17 February 2023), Figs 1.9 and 1.10
- ULTRAOX ST datasheet, p. 5 (model table)
Ultra Controlo figures come from its technical datasheets. Third-party facts were read at the source on the date shown.