Pipeline systems
Diversity factor
A diversity factor is the allowance a medical gas designer makes because not every outlet is used at full flow at the same time, so that pipes and plant are sized for a realistic simultaneous demand instead of the sum of every outlet's flow.
HTM 02-01 (2026), the NHS England guidance, says precise prediction of pipeline flow is not possible. It gives a design flow for each terminal unit and, for each department, a formula for the diversified flow (Q), and diversified flows are used to size the pipes. The count is the number of bed spaces, treatment spaces or rooms where the procedure is performed, not the number of terminal units, since a critical care bed may have four or more oxygen outlets.
In HTM 02-01, the allowance depends on the area. For oxygen in operating departments, Q is based on 50 L/min for the first operating room and 10 L/min for the others, because an oxygen flush is unlikely in several rooms at once. For dental air, all chairs are assumed in use in surgeries with up to five chairs, and 60% of the remaining chairs in larger ones.
The Portuguese ACSS ET 03/2006 (2024 revision) asks that distribution sizing also take into account the confirmed number of points of use and the real utilisation coefficients.
Sources
- HTM 02-01 (2026) Part A, paragraphs 4.2 to 4.6, 4.51 and 4.99 (NHS England)
- ACSS ET 03/2006 v.2024, Gases medicinais (Portugal)
Ultra Controlo figures come from its technical datasheets. Third-party facts were read at the source on the date shown.