# ISO 9170-1: terminal units for compressed medical gases and vacuum

ISO 9170-1:2017 is the international standard for terminal units, the gas-specific outlets of medical gas and vacuum pipelines; it sets requirements for gas-specific assembly, mechanical resistance, flow, leakage and pressure drop, and for preventing interchange between gases, but it does not specify probe dimensions.

## Scope

A terminal unit is the outlet assembly where staff connect medical equipment to a pipeline, on a bed head unit, a wall or a ceiling pendant. ISO 9170-1 covers terminal units for compressed medical gases and vacuum. Its requirements aim at gas-specific assembly, mechanical resistance, flow, leakage and pressure drop, and at preventing a terminal unit from being interchanged between different gases and services.

The standard does not specify the dimensions of probes. National standards define the connection itself: the French [NF S90-116](https://library.ultracontrolo.com/standards/nf-s90-116/), for example, describes the gas-specific quick-connect system between socket and probe and requires the socket to meet NF EN ISO 9170-1.

## Edition and status

ISO 9170-1:2017 is edition 3, published in July 2017. ISO lists it as confirmed at its last systematic review (stage 90.93). Terminal units for anaesthetic gas scavenging systems are in a separate part, [ISO 9170-2:2008](https://library.ultracontrolo.com/standards/iso-9170-2/).

## What it means for hospitals and designers

- Non-interchangeability between gas and vacuum services is a system requirement of [ISO 7396-1](https://library.ultracontrolo.com/standards/iso-7396-1/); ISO 9170-1 applies it at the outlet.
- Because ISO 9170-1 leaves probe dimensions open, a specification should name the connector system as well as the standard, so that outlets, hoses and medical devices match.
- AGSS outlets follow ISO 9170-2 and connect to disposal systems built to [ISO 7396-2](https://library.ultracontrolo.com/standards/iso-7396-2/).

### Does ISO 9170-1 make all oxygen outlets interchangeable between countries?

No. ISO 9170-1 does not specify probe dimensions, so connector systems are defined by national standards such as NF S90-116.

## Sources

- [ISO 9170-1:2017, iso.org](https://www.iso.org/standard/67451.html)
- [ISO 9170-2:2008, iso.org](https://www.iso.org/standard/42056.html)
- [ISO 7396-1:2016, iso.org](https://www.iso.org/standard/60061.html)
- [ISO 7396-2:2007, iso.org](https://www.iso.org/standard/41945.html)
- [AFNOR, NF S90-116 (October 2020)](https://www.boutique.afnor.org/en-gb/standard/nf-s90116/medical-gas-pipeline-distribution-systems-sockets-and-related-probes-for-me/fa191757/260496)
- [Ultra Controlo, Medical gas answers: medical gas pipeline systems](https://www.ultracontrolo.com/medical-gas-answers#what-is-a-medical-gas-pipeline-system)

Reviewed: 2026-10-22. Ultra Controlo engineering. https://library.ultracontrolo.com/standards/iso-9170-1/