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General reference information for facility, lab and supply staff. It is not medical advice and not an installation or testing procedure; work on a medical gas system is governed by the facility’s authority having jurisdiction and its qualified personnel.
Short answer
Medical gas piping is the fixed network that carries oxygen, medical air, nitrous oxide, nitrogen and vacuum from a central source to station outlets, through valves, gauges and alarms. In US practice it is built to NFPA 99, uses cleaned hard-drawn copper tube, is colour-coded and labelled by gas, and is tested and verified by credentialed personnel before it is used for patients.
Definition and scope
The terms medical gas pipeline system and medical gas pipeline describe the same thing as medical gas piping: the distribution side of a facility’s gas supply, as opposed to the source (cylinders, a bulk tank, a compressor or an oxygen plant) or the point of use (a flowmeter or regulator). The US Department of Veterans Affairs master specification, Section 22 63 00, describes a central laboratory and healthcare gas system as oxygen, nitrous oxide, nitrogen and compressed air services including piping, fittings, valves, cabinets, station outlets, rough-ins, ceiling services, gauges and alarms, together with the cylinder manifolds, air compressors, dryers, filters, pressure regulators and dew point and carbon monoxide monitors that feed them.
One boundary is worth knowing. In the VA specification, vacuum is a separate section (22 62 00) and patient bed service walls another (10 25 13), so a project’s gas piping scope does not automatically include them.
How a system is built
Source, piping, valves and alarms, outlets
Reading the VA specification’s scope as a map, a positive-pressure gas system runs in four stages.
| Stage | What the VA Section 22 63 00 scope lists |
|---|---|
| Source | Oxygen ready for connection to an outside bulk tank, or a bulk system with a primary liquid tank, reserve liquid tank and vaporizers; nitrous oxide and nitrogen ready for connection to cylinders; cylinder manifolds; air compressors, dryers, filters and regulators for compressed air |
| Piping | Piping and fittings, including supply lines outside the building |
| Control and monitoring | Valves, gauges, alarms (with low-voltage alarm wiring to alarm panels), dew point and carbon monoxide monitors |
| Delivery | Cabinets, rough-ins, station outlets and ceiling services |
Outlets are covered in more detail in the headwall guide, and the vacuum side in the vacuum regulator guide.
Tube material and cleaning
The NFPA 99 (2012 edition) Chapter 5 excerpts reproduced in NYU Langone Health Safety Policy 133 set out the field-installed material rules:
- Tubes, valves, fittings and station outlets are cleaned for oxygen service by the manufacturer in accordance with CGA G-4.1 before installation (fittings may be cleaned by a supplier or agency other than the manufacturer).
- Tubes are delivered plugged or capped and kept sealed until prepared for installation.
- Tube is hard-drawn seamless copper to ASTM B 819, Type L, except that Type K is used where operating pressure is above 1275 kPa (185 psi) gauge for sizes larger than DN80 (NPS 3).
- B 819 tube carries the manufacturer’s marking OXY, MED, OXY/MED, OXY/ACR or ACR/MED, in blue for Type L and green for Type K.
- The installer furnishes documentation certifying that the installed piping materials meet the cleaning requirement.
Vacuum piping has a wider list: copper tube to ASTM B 88, B 280 or B 819, or stainless steel tube. On the cylinder side, see oxygen cylinder parts and the CGA P-1 safe-handling pamphlet entry.
Gas, colour and pressure reference
NFPA 99 (2012) Table 5.1.11, as reproduced in NYU Langone Health Safety Policy 133 Appendix B, assigns each service a label colour and a standard gauge pressure.
| Service | Label colour (background/text) | Standard gauge pressure |
|---|---|---|
| Oxygen (O2) | Green/white or white/green | 345-380 kPa (50-55 psi) |
| Medical air | Yellow/black | 345-380 kPa (50-55 psi) |
| Nitrous oxide (N2O) | Blue/white | 345-380 kPa (50-55 psi) |
| Carbon dioxide (CO2) | Gray/black or gray/white | 345-380 kPa (50-55 psi) |
| Helium (He) | Brown/white | 345-380 kPa (50-55 psi) |
| Nitrogen (N2) | Black/white | 1,100-1,275 kPa (160-185 psi) |
| Medical-surgical vacuum | White/black | 380-760 mm Hg (15-30 in. HgV) |
| Waste anesthetic gas disposal (WAGD) | Violet/white | Varies with system type |
The same excerpts require pipe labels that name the gas or give its chemical symbol and show the colour code, with the operating pressure added where it differs from the table. Labels go at intervals of not more than 6.1 m (20 ft), at least once in or above every room, on both sides of walls or partitions the piping passes through, and at least once per story height on risers.
Who installs, verifies and maintains
Each phase is tied to a credential from the ASSE 6000 series of professional qualifications standards for medical gas systems. NYU Langone’s policy, which is one hospital system’s rule and not a universal requirement, applies them like this:
| Phase | Credential the policy requires |
|---|---|
| Installation and self-test | ASSE 6010 |
| Final verification and certificate of verification (third party) | ASSE 6030 |
| Maintenance and repairs | ASSE 6040 |
The VA specification points the same way: installers must meet ASSE Series 6000 qualifications, and testing and system verification must be done by personnel meeting the same series, by a party other than the installing contractor. The VA testing agency must submit a procedure covering cross-connection tests, outlet function tests, alarm tests and purity tests.
Where it matters for labs, clinics and supply decisions
- Edition in force. The Centers for Medicare & Medicaid Services enforces the 2012 edition of NFPA 99 for hospitals under 42 CFR 482.41, while the current published edition is 2024. A chapter citation from a newer handbook does not necessarily match the enforced text.
- Authorization before work. The NYU policy requires facilities authorization and location of the nearest isolation valve before any work on outlets or piping.
- Documentation travels with the job. Cleaning certification of materials (NFPA 99 5.1.10.1.6), the testing agency’s procedure and the certificate of verification are the records these sources call for.
Equipment standards for the devices that plug into the system, such as flowmeters, sit separately; see IEC 60601-1 for the electrical safety standard family.
Common misunderstandings
Is medical gas piping the same as plumbing?
No. In the VA master specification it falls under its own section, Section 22 63 00, with its own qualification, cleaning and testing requirements, separate from general plumbing.
Is any copper pipe acceptable?
No. NFPA 99 (2012) calls for ASTM B 819 medical gas tube cleaned for oxygen service and delivered capped, marked OXY, MED, OXY/MED, OXY/ACR or ACR/MED.
Does one colour and pressure apply to every gas?
No. Nitrogen is listed at 1,100-1,275 kPa while oxygen, medical air and nitrous oxide are listed at 345-380 kPa, and each has its own label colour.
Is the installer’s own test enough?
Not under the sources listed on this page. The NYU policy follows the installer’s self-test with a third-party ASSE 6030 verifier, and the VA specification requires testing by a party other than the installing contractor.
FAQ
What is a medical gas pipeline system?
It is the installed network of piping, valves, alarms and station outlets that distributes medical gases and vacuum from a central source to points of use in a facility. The VA specification lists these components in its description of a central gas system.
What is medical gas piping made of?
For field-installed positive-pressure systems, NFPA 99 (2012) specifies hard-drawn seamless copper to ASTM B 819, Type L, with Type K above 1275 kPa (185 psi) for sizes larger than DN80.
How are medical gas pipes identified?
By stenciled or adhesive labels naming the gas and showing its colour code, spaced at no more than 6.1 m (20 ft) and placed in every room and on both sides of penetrated walls.
Who may test a medical gas system?
Under the NYU policy, ASSE 6010 personnel self-test and an ASSE 6030 third-party verifier signs off. The VA specification requires personnel meeting ASSE Series 6000 and independence from the installing contractor.
How often is a system inspected?
NYU Langone Health’s policy sets inspection and testing of the whole distribution system at least annually. That is one institution’s requirement; an authority having jurisdiction may set its own.
Sources
- US Department of Veterans Affairs, Master Specification Section 22 63 00, Gas Systems for Laboratory and Healthcare Facilities, revision 05-01-23: wbdg.org VA 22 63 00 (checked 2026-10-30).
- NYU Langone Health, Safety Policy 133, Medical Gas Outlets and Piping, revised July 1, 2025, including excerpts of NFPA 99 (2012) Chapter 5 and Table 5.1.11: nyulangone.org policy 133 (checked 2026-10-30).
- 42 CFR 482.41, Physical environment, incorporating NFPA 99 (2012 edition) by reference: ecfr.gov 42 CFR 482.41 (checked 2026-10-30).
