# Which gases does a hospital pipeline system carry?

**Which gases and services does a hospital medical gas pipeline system carry?**

Under ISO 7396-1 and NHS England's HTM 02-01, a hospital pipeline system can carry oxygen or oxygen 93, medical air, surgical air or nitrogen for driving tools, nitrous oxide and its 50/50 mixture with oxygen, carbon dioxide and medical vacuum. Anaesthetic gas scavenging is a separate disposal system covered by ISO 7396-2.

## The services in ISO 7396-1

ISO 7396-1:2016, the international standard for pipeline systems for compressed medical gases and vacuum, covers oxygen, oxygen 93, nitrous oxide, medical air, carbon dioxide, gases for driving surgical tools and vacuum. Where every source delivers oxygen 93, the oxygen concentration in the pipeline may vary between 90% and 96%. Anaesthetic gas scavenging disposal systems are covered by ISO 7396-2, and units that blend oxygen and nitrogen into synthetic medical air or tool air by ISO 7396-3:2025.

## The services in NHS England's HTM 02-01

HTM 02-01 (2026 edition) lists pipeline identification for these services, each with its own colour band and label:

| Service | Main use | Nominal pressure in HTM 02-01 |
|---|---|---|
| Oxygen (O2) | Patient oxygen supply | 400 kPa |
| Nitrous oxide (N2O) | Anaesthesia | 400 kPa |
| Oxygen/nitrous oxide 50%/50% | Labour, delivery and recovery rooms, among others | 400 kPa |
| Medical air (MA4) | Driving ventilators and other respiratory uses | 400 kPa |
| Surgical air (SA7) | Driving surgical tools | 700 kPa |
| Dental air (DA) | Driving dental tools | 600 kPa |
| Medical vacuum (MV) | Clinical suction | Below atmospheric pressure |
| Carbon dioxide (CO2), surgical nitrogen (SN), oxygen/helium 21%/79% | Specialist uses | Not in Table 30 |
| Anaesthetic gas scavenging (AGS) and dental vacuum (DV) | Removal of waste anaesthetic gas; dental suction | Below atmospheric pressure |

HTM 02-01 also has a chapter on other medical gases: local supplies of liquid nitrogen, nitric oxide, heliox and carbon dioxide. Portugal's ACSS specification ET 03/2006 (2024 revision) sets the minimum number of outlets for oxygen, carbon dioxide, nitrous oxide, vacuum and medical air at 400 kPa and 700 kPa, counted, depending on the area, per bed, per room, per incubator, per treatment position or per resuscitation table.

## What is changing

The 2026 HTM 02-01 reports that anaesthetic organisations have recommended that piped nitrous oxide should no longer be considered in modern anaesthetic practice, with a move to point-of-use cylinders. It also notes that surgical air use is declining as battery and electrically powered tools spread, and that the need for medical air and surgical air in each project is decided through its informed design process. Which services a hospital pipes is therefore a design decision.

Ultra Controlo designs and manufactures supply plants for several of these services: ULTRAOX PSA plants for oxygen at 94% (±1%) purity, ULTRAAR medical air plants, ULTRAVAC medical vacuum plants and ULTRASEG anaesthetic gas scavenging systems.

### Is oxygen 93 piped in the same network as oxygen above 99%?

ISO 7396-1 covers supply systems that deliver a mixture of oxygen 93 and oxygen, with a concentration between 90% and above 99%. Portugal's ACSS recommends a separate or dedicated network for oxygen 93.

### Is anaesthetic gas scavenging part of the medical gas pipeline?

It is treated separately: ISO 7396-2 covers anaesthetic gas scavenging disposal systems, while ISO 7396-1 covers compressed medical gases and vacuum.

## Sources

- [ISO 7396-1:2016, ISO 7396-2:2007 and ISO 7396-3:2025, official summaries](https://www.iso.org/standard/60061.html)
- [HTM 02-01 (2026) Part A, Figure 25, paragraphs 4.79, 4.89, 4.96 and chapter 13, Major changes since the 2006 edition, NHS England](https://www.england.nhs.uk/wp-content/uploads/2016/05/health-technical-memorandum-02-01-medical-gas-pipeline-systems-part-a-design-installation-validation-verification-aug-2026.pdf)
- [ACSS ET 03/2006 v.2024, annex Gases medicinais e aspiração](https://www.acss.min-saude.pt/wp-content/uploads/2016/10/ET-03_2006_v2024-Gases-medicinais_VF.pdf)
- [ULTRAOX SC datasheet, p. 2](https://www.ultracontrolo.com/products/ultraox)
- [ULTRAOX ST datasheet, p. 2](https://www.ultracontrolo.com/products/ultraox-st)
- [ULTRAAR SC datasheet](https://www.ultracontrolo.com/products/ultraar-sc)
- [ULTRAVAC datasheet](https://www.ultracontrolo.com/products/ultravac)
- [ULTRASEG datasheet](https://www.ultracontrolo.com/products/ultraseg)

Reviewed: 2026-10-22. Ultra Controlo engineering. https://library.ultracontrolo.com/answers/what-gases-does-a-hospital-pipeline-carry/