How must medical gas pipes be labelled?

What the marking shows

In the references below, pipeline marking covers three things: the gas, in words or symbol; its colour code; and the direction of flow. Valves are marked with the gas and the area or branch they control.

English rules (HTM 02-01 Part A, 2026)

• Pipelines are identified to BS 1710 with colour banding.
• Colour bands go within 300 mm of valves and junctions and on both sides of walls and similar structures; a band width of 150 mm is usually adequate.
• A label naming the gas, with lettering at least 6 mm high, is applied at intervals not exceeding 3 m.
• Colour tapes applied by pipe manufacturers are removed before identification, and identification is kept when pipes are repainted.
• The direction of flow is shown; on ring mains, two arrows facing outwards show that flow can go either way.
• Pipes inside medical supply units, such as bed-head trunking, are labelled the same way.
• Line valves carry gas identity and flow direction on the pipe within 1 m on each side. Each area valve is labelled with its number, the rooms or outlets it serves, the gas, the flow direction and its key cabinet number.

Portugal (ACSS ET 03/2006, revised 2024)

Networks are identified according to ISO 7396 using the colour code of that standard, and every shut-off valve is marked with the gas or its symbol and the branch or area it controls, on the valve or on the pipe.

Colours can differ between countries

WHO notes, for outlet colours, that local and international standards vary, and ISO 32 is a colour system for gas cylinders. Use the colour table of the standard that applies to the project rather than colours from another country. Labelling is also checked during commissioning and after work: HTM 02-01 lists a check of pipeline identification, flow-direction tape and the markings on area valves, NIST connectors and outlets.