Medical Gas Pipeline Systems Design: Diversity, Pipe Sizing, Zoning and Redundancy

Start with the clinical schedule

Design begins with a schedule of rooms, beds and equipment. For each room type define the gases and vacuum required, the number of terminal units and the type of terminal unit: wall outlet, bed head unit, beam or pendant. The more precise the brief, the less the design carries unnecessary margin.

Agree early which standard governs: HTM 02-01 and ISO 7396-1 are close in principle but differ in details, and NFPA 99 follows a different, risk-category approach. The comparison is in HTM 02-01 versus NFPA 99 versus ISO 7396.

Flow, diversity and design demand

Connected demand is the sum of flows at all terminals, which would greatly overestimate real use. Standards therefore provide diversity factors and design flows per terminal unit, varying by department and gas. Multiply the number of terminals by the flow per terminal, apply the diversity factor for that department and add continuous loads such as ventilators.

Calculate demand per branch, per riser and for the entire source, and record the assumptions. For oxygen, calibrate the result against actual consumption data where available; see hospital oxygen consumption calculation.

Pipe sizing and pressure

Pipework is sized so that pressure at the farthest terminal under design flow stays within the limits set by the standard. Nominal pipeline pressure for oxygen, nitrous oxide and medical air is commonly about 400 kPa, and surgical air is higher, but confirm the figures in the standard you are using. Calculate the pressure drop with a recognised method for each section and select the diameter, then check velocity and noise.

Consider route length, number of bends and risers and account for future extensions. Pipe material is normally degreased medical-grade copper, jointed by brazing under inert gas, with documentation of cleanliness.

Zoning, valves and isolation

Zoning decides how much of the hospital is affected when a section is closed for work or in an emergency. Place isolation valves at the plant, at each riser and, per department, in area valve service units. The Digital AVSU from MZ Liberec serves one to six gas lines, shows pressure on an LED display and links to the MZU II. See the Digital AVSU and area valve service units.

Position the valves where staff can reach them, with a clear label of the area served, and agree locations with the fire strategy, since smoke compartments often drive zoning.

Source capacity and redundancy

Each source is designed for peak demand with redundancy: primary, secondary and, where required, a reserve. Oxygen can use liquid tanks, cylinders or an on-site plant; compressors and vacuum pumps use duty and standby units. The MIL's range from MZ Liberec covers oxygen concentrators of 3 to 48 Nm³/h of O₂, compressor stations of 2.2 to 608 Nm³/h and vacuum stations of 6.4 to 632 Nm³/h, all part of the manufacturer's complete medical gas solutions. See MZ Liberec.

Source logic is expanded in how hospitals get oxygen.

Alarms, documentation and testing

Verification follows the steps in testing and commissioning. For UAE projects, confirm authority requirements from MOHAP, DHA or DOH early.

Beckfinity can support your design team with MZ Liberec product data; contact our specialists to discuss.

• Source alarms, area alarms and master alarms defined in the design.
• A clear schedule of zones, valves and alarm panels.
• Drawings showing pipe sizes, routes and valve locations.
• Test and commissioning requirements written into the specification.
• Labelling and colour conventions agreed (see the colour code).