National foreword

This British Standard is the UK implementation of EN ISO 18777‑1:2026. It is identical to ISO 18777‑1:2026. Together with BS EN ISO 18777‑2:2025, it supersedes BS EN ISO 18777:2009 which is withdrawn.

The UK participation in its preparation was entrusted to Technical Committee CH/121/6, Medical gas supply systems.

A list of organizations represented on this committee can be obtained on request to its committee manager.

Contractual and legal considerations

This publication has been prepared in good faith, however no representation, warranty, assurance or undertaking (express or implied) is or will be made, and no responsibility or liability is or will be accepted by BSI in relation to the adequacy, accuracy, completeness or reasonableness of this publication. All and any such responsibility and liability is expressly disclaimed to the full extent permitted by the law.

This publication is provided as is, and is to be used at the recipient’s own risk.

The recipient is advised to consider seeking professional guidance with respect to its use of this publication.

This publication is not intended to constitute a contract. Users are responsible for its correct application.

Compliance with a British Standard cannot confer immunity from legal obligations.

This British Standard was published under the authority of the Standards Policy and Strategy Committee on 31 March 2026.

This European Standard was approved by CEN on 3 January 2026.

CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such national standards may be obtained on application to the CEN-CENELEC Management Centre or to any CEN member.

This European Standard exists in three official versions (English, French, German). A version in any other language made by translation under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC Management Centre has the same status as the official versions.

CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czechia, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Türkiye and United Kingdom.

European foreword

This document (EN ISO 18777‑1:2026) has been prepared by Technical Committee ISO/TC 121 "Anaesthetic and respiratory equipment" in collaboration with Technical Committee CEN/TC 215 “Respiratory and anaesthetic equipment” the secretariat of which is held by BSI.

This European Standard shall be given the status of a national standard, either by publication of an identical text or by endorsement, at the latest by September 2026, and conflicting national standards shall be withdrawn at the latest by September 2026.

Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. CEN shall not be held responsible for identifying any or all such patent rights.

This document supersedes EN ISO 18777:2009.

Any feedback and questions on this document should be directed to the users’ national standards body/national committee. A complete listing of these bodies can be found on the CEN website.

According to the CEN-CENELEC Internal Regulations, the national standards organizations of the following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Türkiye and the United Kingdom.

Endorsement notice

The text of ISO 18777‑1:2026, Corrected version 2026-09 has been approved by CEN as EN ISO 18777‑1:2026 without any modification.

Foreword

ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of preparing International Standards is normally carried out through ISO technical committees. Each member body interested in a subject for which a technical committee has been established has the right to be represented on that committee. International organizations, governmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.

The procedures used to develop this document and those intended for its further maintenance are described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the different types of ISO document should be noted. This document was drafted in accordance with the editorial rules of the ISO/IEC Directives, Part 2 (see www.iso.org/directives).

ISO draws attention to the possibility that the implementation of this document may involve the use of (a) patent(s). ISO takes no position concerning the evidence, validity or applicability of any claimed patent rights in respect thereof. As of the date of publication of this document, ISO had not received notice of (a) patent(s) which may be required to implement this document. However, implementers are cautioned that this may not represent the latest information, which may be obtained from the patent database available at www.iso.org/patents. ISO shall not be held responsible for identifying any or all such patent rights.

Any trade name used in this document is information given for the convenience of users and does not constitute an endorsement.

For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and expressions related to conformity assessment, as well as information about ISO's adherence to the World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT), see www.iso.org/iso/foreword.html.

This document was prepared by Technical Committee ISO/TC 121 Anaesthetic and respiratory equipment Subcommittee SC 6, Medical gas supply systems in collaboration with the European Committee for Standardization (CEN) Technical Committee CEN/TC 215, Respiratory and anaesthetic equipment, in accordance with the Agreement on technical cooperation between ISO and CEN (Vienna Agreement).

This first edition together with ISO 18777‑2 cancels and replaces ISO 18777:2005 which has been technically revised.

The main changes are as follows:

part 1 includes requirements that are common to both base units and portable units.
requirements for the transfilling device have been included.

A list of all parts in the ISO 18777 series can be found on the ISO website.

Any feedback or questions on this document should be directed to the user’s national standards body. A complete listing of these bodies can be found at www.iso.org/members.html.

This corrected version of ISO 18777-1:2026 incorporates the following corrections:

— Correction to cross reference errors.

Introduction

Transportable liquid oxygen systems comprise a base unit and a portable unit for use primarily in home-care applications and without professional supervision. This document specifies requirements that are common to both base units and portable units and requirements that are particular to base units. Base units can be used solely to store the liquid oxygen for refilling the portable unit or can, if fitted with a flow outlet and flow control, also be used to provide a controlled flow of oxygen for inhalation by the patient.

Base units comprise:

a double-walled vacuum-insulated cryogenic container for storing liquid oxygen (LOX) at approximately –180 °C;
a content level indicator;
a heat exchanger to convert liquid oxygen to gaseous oxygen and warming it to ambient temperature;
a transfilling device; and
can also include a separate filling connector.

Annex A contains rationale for some of the requirements. It is included to provide additional insight into the committee’s reasoning that led to a particular requirement to address the identified hazards.

1 Scope

This document specifies requirements for transportable liquid oxygen systems that are common to both base units and portable units and requirements that are particular to base units.

Stationary liquid oxygen systems used for oxygen pipeline supply systems are excluded from this document.

NOTE 1 Throughout this document the term “units” is used where the requirement applies to both base units and portable units.

NOTE 2 ISO 18777 ‑ 2 specifies those requirements particular to portable units.

2 Normative references

3 Terms and definitions

4 General requirements

4.1 Risk management

4.2 Usability

4.3 Materials

4.4 Environmental conditions

5 Design requirements

5.1 Cryogenic vessels

5.2 Contents level indication

5.3 Transfilling devices and filling port connectors

5.4 Interoperability between the base unit and the portable unit

5.5 Flow outlets

5.6 Oxygen temperature at the flow outlet

5.7 Flow control device

5.8 Pressure at the flow outlet

5.9 Oxygen conserving device

5.10 Venting of gaseous oxygen

5.11 Pressure control

5.12 Evaporation rate

5.13 Leakage

5.14 Excessive temperatures of accessible surfaces

5.15 Electrical safety

5.16 Protection of components and controls

5.17 Stability

5.18 Battery compartments

6 Construction requirements

7 Information to be supplied by the manufacturer

7.1 General

7.2 Marking

7.3 Instructions for use for the intended user

Bibliography