SIST EN IEC 63359:2026

Fluids for electrotechnical application: Specifications for the re-use of mixtures of gases alternative to sf6

This document provides the quality of gases alternative to SF6 (subsequently referred to as gases) for their re-use in electrical power equipment after recovery and if applicable reclaiming (e.g., during maintenance, repair, overhaul or at the end-of-life). The re-use criteria consider technical and environmental concerns.
This document covers the same gases as listed in IEC 63360. For gases not mentioned in this document, the electrical power equipment manufacturer and/or the gas manufacturer provide the information indicated in this document. It is the intention of this document to include such gases in a next edition or in amendments to this edition.
Procedures for recovering and reclaiming of used gases are described in IEC 62271-4:2022.
NOTE 1 Reclaiming procedures of gases can be done by either reclaiming the complete gas or by separating the most valuable components from the gas.
Gas analysis techniques for checking the quality of the gas are described in this document.
It is the responsibility of the gas manufacturer and/or the electrical power equipment manufacturer to provide sufficient information for safe handling of gases and to provide a risk assessment. It is the responsibility of the user of the electrical power equipment to establish appropriate health and safety practices and to determine the applicability of regulatory limitations prior to use.
NOTE 2 If not otherwise specified in this document, concentration values (e.g. %, ppmv, μl/l) of gas components or contaminants are given in volume fraction at 20 °C and 100 kPa. More information on temperature and pressure dependence of mole fraction and volume fraction is given in IEC 63360:2025, Annex C.
NOTE 3 If gases for electrical power equipment are regulated, their designation and regulation origin can be found in the IEC 62474 database [1]1 (available at https://std.iec.ch/iec62474).
NOTE 4 Information about storage, transportation and disposal of gases, gas properties, safety and first aid, environmental impact, training and certification, handling equipment, by-products, and procedures to evaluate the potential effects on health are covered by IEC 62271-4:2022.

Flüssigkeiten für elektrotechnische Anwendungen: Spezifikationen für die Wiederverwendung von Gasgemischen als Alternative zu SF6

Fluides pour applications électrotechniques: Spécifications pour la réutilisation des mélanges de gaz alternatifs au sf6

IEC 63359:2026 Le présent document définit la qualité des gaz alternatifs au SF6 (ci-après appelés "gaz") en vue de leur réutilisation dans les matériels électriques après récupération et, le cas échéant, régénération (par exemple, au cours de la maintenance, de la réparation, de la révision ou en fin de vie).

Tekočine za elektrotehniko - Specifikacija za ponovno uporabo mešanice plinov kot alternativa žveplovemu heksafluoridu (SF6)

Ta dokument določa kakovost plinov, ki so alternativa SF6 (v nadaljevanju imenovani plini) za njihovo ponovno uporabo v električni opremi po obnovi in, če je primerno, regeneraciji (npr. med vzdrževanjem, popravilom, remontom ali ob koncu življenjske dobe). Merila za ponovno uporabo upoštevajo tehnične in okoljske vidike.
Ta dokument zajema iste pline, kot so navedeni v IEC 63360. Za pline, ki niso omenjeni v tem dokumentu, proizvajalec električne opreme in/ali proizvajalec plina zagotovi informacije, navedene v tem dokumentu. Namen tega dokumenta je vključiti takšne pline v naslednjo izdajo ali v dopolnila k tej izdaji.
Postopki za obnovo in regeneracijo uporabljenih plinov so opisani v IEC 62271-4:2022.
OPOMBA 1 Postopki regeneracije plinov se lahko izvajajo bodisi z regeneracijo celotnega plina bodisi z ločevanjem najvrednejših komponent iz plina.
Tehnike analize plinov za preverjanje kakovosti plina so opisane v tem dokumentu.
Odgovornost proizvajalca plina in/ali proizvajalca električne opreme je, da zagotovi zadostne informacije za varno ravnanje s plini in da zagotovi oceno tveganja. Odgovornost uporabnika električne opreme je, da vzpostavi ustrezne prakse za zdravje in varnost ter da pred uporabo določi uporabnost regulativnih omejitev.
OPOMBA 2 Če v tem dokumentu ni drugače določeno, so koncentracijske vrednosti (npr. %, ppmv, μl/l) komponent plina ali onesnaževalcev podane v volumskem deležu pri 20 °C in 100 kPa. Več informacij o temperaturni in tlačni odvisnosti molskega in volumskega deleža je podano v IEC 63360:2025, Priloga C.
OPOMBA 3 Če so plini za električno opremo regulirani, se njihova oznaka in izvor regulacije lahko najde v bazi podatkov IEC 62474 [1]1 (dostopno na https://std.iec.ch/iec62474).
OPOMBA 4 Informacije o skladiščenju, prevozu in odstranjevanju plinov, lastnostih plinov, varnosti in prvi pomoči, vplivu na okolje, usposabljanju in certificiranju, opremi za ravnanje, stranskih produktih ter postopkih za oceno potencialnih učinkov na zdravje so zajete v IEC 62271-4:2022.

General Information

• Status: Published
• Public Enquiry End Date: 19-Jan-2025
• Publication Date: 11-May-2026
• ICS: 23 - FLUID SYSTEMS AND COMPONENTS FOR GENERAL USE
• ICS: 29.040.20 - Insulating gases
• ICS: 71.100.20 - Gases for industrial application
• Technical Committee: TPD - Fluids for electrotechnical applications
• Current Stage: 6060 - National Implementation/Publication (Adopted Project)
• Start Date: 07-Apr-2026
• Due Date: 12-Jun-2026
• Completion Date: 12-May-2026
• Ref Project: EN IEC 63359:2026 - Fluids for electrotechnical application: Specifications for the re-use of mixtures of gases alternative to SF6

Relations

• Refers: SIST EN IEC 63360:2025 - Fluids for electrotechnical application: Mixtures of gases alternative to SF6
• Effective Date: 10-Mar-2026
• Refers: SIST IEC 60050-603:1997 - International Electrotechnical Vocabulary. Chapter 603: Generation, transmission and distribution of electricity - Power systems planning and management
• Effective Date: 10-Mar-2026

Overview

SIST EN IEC 63359:2026 establishes the quality specifications for the re-use of mixtures of gases alternative to sulfur hexafluoride (SF₆) in electrical power equipment. This standard is crucial for supporting the ongoing shift to environmentally friendlier insulating and switching gases, helping manufacturers, utility operators, and service providers meet regulatory and technical requirements when recovering and reclaiming used alternative gases.

Developed by CLC and IEC Technical Committee 10, this document defines requirements for the analysis, assessment, and cleaning (reclaiming) of used gas mixtures so they can be safely and effectively reintroduced into high-voltage and medium-voltage equipment. The guidance provided supports both technical performance and environmental responsibility throughout the lifecycle of insulating gases.

Key Topics

• Scope of Application: The standard specifies the criteria for re-using recovered and, if necessary, reclaimed gas mixtures that serve as alternatives to SF₆, including compressed air, synthetic air, and specialized fluorinated mixtures.
• Contaminant Control: Identifies typical contaminants (e.g., air, water vapor, oil, by-products from electrical arcing) and their sources. It underscores procedures for evaluation and removal.
• Quality Assessment: Outlines requirements and methods for analyzing gas quality, covering both on-site and laboratory-based techniques.
  • On-site analysis methods include infrared absorption and electrochemical sensors.
  • Laboratory analysis may use gas chromatography (GC) and Fourier-transform infrared spectroscopy (FTIR).
• Specifications for Re-use: Contains detailed criteria and limits for allowable contaminant levels based on the specific gas mixture, ensuring electrical and environmental performance.
• Reclaiming Process: Describes feasible on-site and off-site reclaiming measures, highlighting the role of filtration and adsorptive removal processes for humidity, solid particles, gaseous by-products, and oils.
• Decision Workflow: Presents a practical decision flow chart to support operators in determining the right approach for handling, reclaiming, or disposing of recovered gases.

Applications

SIST EN IEC 63359:2026 provides essential guidance for:

• Utilities and Service Providers: Ensures that recovered alternative gases from power equipment-such as gas-insulated switchgear, busbars, transformers, and circuit breakers-can be reliably re-used or safely disposed of according to up-to-date environmental and safety practices.
• Manufacturers: Helps gas and equipment manufacturers deliver equipment that facilitates regulatory compliance and optimum lifecycle management for alternative insulating gases.
• Maintenance and Overhaul: Supports field technicians and maintenance operators with dependable procedures for recovering, assessing, and treating used gases during routine servicing, end-of-life operations, or after fault events.
• Environmental Compliance: Facilitates the reduction of greenhouse gas emissions by outlining the safe and effective re-use of gases, minimizing the release and disposal of potent gases such as SF₆.

Related Standards

Implementing SIST EN IEC 63359:2026 typically involves reference to complementary standards:

• IEC 62271-4:2022 – Handling procedures for gases for insulation and/or switching in high-voltage switchgear and controlgear.
• IEC 63360:2024 – Specifications of mixtures of gases alternative to SF₆ for use in power equipment.
• IEC 60480:2019 – Specifications for the re-use of SF₆ and its mixtures in electrical equipment.
• IEC Electropedia (IEC 60050 series) – Vocabulary for electrical insulating fluids and gases.
• IEC 62474 – Material declaration requirements for electrotechnical products.

Practical Value

By following SIST EN IEC 63359:2026, users can:

• Promote sustainability and reduce environmental impact in the power sector by enabling the responsible re-use of alternative insulating gases.
• Standardize procedures for gas quality control and equipment maintenance, improving reliability, operational safety, and cost-effectiveness.
• Maintain compliance with evolving international and regional regulations for greenhouse gas alternatives in electrical applications.
• Strengthen environmental, health, and safety management throughout the life cycle of gases for high-voltage applications.

Standards Content (Sample)

SLOVENSKI STANDARD
01-junij-2026
Tekočine za elektrotehniko - Specifikacija za ponovno uporabo mešanice plinov
kot alternativa žveplovemu heksafluoridu (SF6)
Fluids for electrotechnical application: Specifications for the re-use of mixtures of gases
alternative to sf6
Flüssigkeiten für elektrotechnische Anwendungen: Spezifikationen für die
Wiederverwendung von Gasgemischen als Alternative zu SF6
Fluides pour applications électrotechniques: Spécifications pour la réutilisation des
mélanges de gaz alternatifs au sf6
Ta slovenski standard je istoveten z: EN IEC 63359:2026
ICS:
29.040.20 Izolacijski plini Insulating gases
71.100.20 Industrijski plini Gases for industrial
application
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EUROPEAN STANDARD EN IEC 63359

NORME EUROPÉENNE
EUROPÄISCHE NORM March 2026
ICS 29.040.20
English Version
Fluids for electrotechnical application: Specifications for the re-
use of mixtures of gases alternative to SF6
(IEC 63359:2026)
Fluides pour applications électrotechniques : Spécifications Flüssigkeiten für elektrotechnische Anwendungen:
pour la réutilisation des mélanges de gaz alternatifs au SF6 Spezifikationen für die Wiederverwendung von
(IEC 63359:2026) Gasgemischen als Alternative zu SF6
(IEC 63359:2026)
This European Standard was approved by CENELEC on 2026-03-16. CENELEC 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 CENELEC 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 CENELEC member into its own language and notified to the CEN-CENELEC Management Centre has the
same status as the official versions.
CENELEC members are the national electrotechnical committees of Austria, Belgium, Bulgaria, Croatia, Cyprus, the Czech Republic,
Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, the
Netherlands, Norway, Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland,
Türkiye and the United Kingdom.

European Committee for Electrotechnical Standardization
Comité Européen de Normalisation Electrotechnique
Europäisches Komitee für Elektrotechnische Normung
CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2026 CENELEC All rights of exploitation in any form and by any means reserved worldwide for CENELEC Members.
Ref. No. EN IEC 63359:2026 E
European foreword
The text of document 10/1296/FDIS, future edition 1 of IEC 63359, prepared by TC 10 "Fluids for
electrotechnical applications" was submitted to the IEC-CENELEC parallel vote and approved by
CENELEC as EN IEC 63359:2026.
The following dates are fixed:
• latest date by which the document has to be implemented at national (dop) 2027-03-31
level by publication of an identical national standard or by endorsement
• latest date by which the national standards conflicting with the (dow) 2029-03-31
document have to be withdrawn
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CENELEC shall not be held responsible for identifying any or all such patent rights.
Any feedback and questions on this document should be directed to the users’ national committee. A
complete listing of these bodies can be found on the CENELEC website.
Endorsement notice
The text of the International Standard IEC 63359:2026 was approved by CENELEC as a European
Standard without any modification.
In the official version, for Bibliography, the following notes have to be added for the standard indicated:
IEC 60480:2019 NOTE Approved as EN IEC 60480:2019 (not modified)
IEC 62271-4:2022 NOTE Approved as EN IEC 62271-4:2022 (not modified)
Annex ZA
(normative)
Normative references to international publications
with their corresponding European publications
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any amendments)
applies.
NOTE 1  Where an International Publication has been modified by common modifications, indicated by (mod),
the relevant EN/HD applies.
NOTE 2  Up-to-date information on the latest versions of the European Standards listed in this annex is available
here: www.cencenelec.eu.
Publication Year Title EN/HD Year
IEC 60050-212 2010 International Electrotechnical Vocabulary - - -
Part 212: Electrical insulating solids, liquids
and gases
IEC 60050-426 2020 International Electrotechnical Vocabulary - -
(IEV) - Part 426: Explosive atmospheres
IEC 60050-441 - International Electrotechnical Vocabulary. - -
Switchgear, controlgear and fuses
IEC 63360 2025 Fluids for electrotechnical application - EN IEC 63360 2025
Specification of gases alternative to SF6 to
be used in electrical power equipment

IEC 63359 ®
Edition 1.0 2026-02
INTERNATIONAL
STANDARD
Fluids for electrotechnical application: Specifications for the re-use of mixtures
of gases alternative to SF
ICS 29.040.20  ISBN 978-2-8327-1040-1

IEC 63359:2026-02(en)
IEC 63359:2026 © IEC 2026
CONTENTS
FOREWORD . 2
1 Scope . 4
2 Normative references . 4
3 Terms and definitions and abbreviated terms . 5
3.1 Terms and definitions . 5
3.2 Abbreviated terms. 7
4 Contaminants and their sources . 7
4.1 General . 7
4.2 Contaminants from handling and use . 7
5 Specifications for used single gases suitable for reuse . 8
6 Specifications for used gas suitable for reuse . 8
7 Reclaiming of gases for re-use in electrical power equipment . 10
7.1 Feasibility and process . 10
7.2 Gas analysis techniques for checking the quality of the gas . 11
7.2.1 General. 11
7.2.2 On-site analysis . 11
7.2.3 Laboratory analysis . 12
Bibliography . 13

Figure 1 – Decision flow chart for recovered gas intended to be re-used or disposed . 11

Table 1 – Most common contaminants of gases . 7
Table 2 – Specifications for re-use of mixtures of C5-FK with O and N . 8
2 2
Table 3 – Specifications for re-use of mixtures of C4-FN with CO . 8
Table 4 – Specifications for re-use of mixtures of C4-FN with O and CO . 9

2 2
Table 5 – Specifications for re-use of mixtures of C4-FN with O and N . 9
2 2
Table 6 – Specifications for re-use of mixtures of CO and O . 9
2 2
Table 7 – Specifications for re-use of mixtures of CO and N . 9
2 2
Table 8 – Specifications for re-use of mixtures of CO , O and N . 10
2 2 2
Table 9 – Most common methods for the removal of contaminants. 10
Table 10 – Most common laboratory analysis techniques . 12

IEC 63359:2026 © IEC 2026
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
Fluids for electrotechnical application -
Specifications for the re-use of mixtures of gases alternative to SF
FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
all national electrotechnical committees (IEC National Committees). The object of IEC is to promote international
co-operation on all questions concerning standardization in the electrical and electronic fields. To this end and
in addition to other activities, IEC publishes International Standards, Technical Specifications, Technical Reports,
Publicly Available Specifications (PAS) and Guides (hereafter referred to as “IEC Publication(s)”). Their
preparation is entrusted to technical committees; any IEC National Committee interested in the subject dealt with
may participate in this preparatory work. International, governmental and non-governmental organizations liaising
with the IEC also participate in this preparation. IEC collaborates closely with the International Organization for
Standardization (ISO) in accordance with conditions determined by agreement between the two organizations.
2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international
consensus of opinion on the relevant subjects since each technical committee has representation from all
interested IEC National Committees.
3) IEC Publications have the form of recommendations for international use and are accepted by IEC National
Committees in that sense. While all reasonable efforts are made to ensure that the technical content of IEC
Publications is accurate, IEC cannot be held responsible for the way in which they are used or for any
misinterpretation by any end user.
4) In order to promote international uniformity, IEC National Committees undertake to apply IEC Publications
transparently to the maximum extent possible in their national and regional publications. Any divergence between
any IEC Publication and the corresponding national or regional publication shall be clearly indicated in the latter.
5) IEC itself does not provide any attestation of conformity. Independent certification bodies provide conformity
assessment services and, in some areas, access to IEC marks of conformity. IEC is not responsible for any
services carried out by independent certification bodies.
6) All users should ensure that they have the latest edition of this publication.
7) No liability shall attach to IEC or its directors, employees, servants or agents including individual experts and
members of its technical committees and IEC National Committees for any personal injury, property damage or
other damage of any nature whatsoever, whether direct or indirect, or for costs (including legal fees) and
expenses arising out of the publication, use of, or reliance upon, this IEC Publication or any other IEC
Publications.
8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
indispensable for the correct application of this publication.
9) IEC draws attention to the possibility that the implementation of this document may involve the use of (a)
patent(s). IEC 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, IEC had 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 https://patents.iec.ch. IEC
shall not be held responsible for identifying any or all such patent rights.
IEC 63359 has been prepared by IEC technical committee 10: Fluids for electrotechnical
applications. It is an International Standard.
The text of this International Standard is based on the following documents:
Draft Report on voting
10/1296/FDIS 10/1298/RVD
Full information on the voting for its approval can be found in the report on voting indicated in
the above table.
The language used for the development of this International Standard is English.
IEC 63359:2026 © IEC 2026
This document was drafted in accordance with ISO/IEC Directives, Part 2, and developed in
accordance with ISO/IEC Directives, Part 1 and ISO/IEC Directives, IEC Supplement, available
at www.iec.ch/members_experts/refdocs. The main document types developed by IEC are
described in greater detail at www.iec.ch/publications.
The committee has decided that the contents of this document will remain unchanged until the
stability date indicated on the IEC website under webstore.iec.ch in the data related to the
specific document. At this date, the document will be
– reconfirmed,
– withdrawn, or
– revised.
IEC 63359:2026 © IEC 2026
1 Scope
This document provides the quality of gases alternative to SF (subsequently referred to as
gases) for their re-use in electrical power equipment after recovery and if applicable reclaiming
(e.g., during maintenance, repair, overhaul or at the end-of-life). The re-use criteria consider
technical and environmental concerns.
This document covers the same gases as listed in IEC 63360. For gases not mentioned in this
document, the electrical power equipment manufacturer and/or the gas manufacturer provide
the information indicated in this document. It is the intention of this document to include such
gases in a next edition or in amendments to this edition.
Procedures for recovering and reclaiming of used gases are described in IEC 62271-4:2022.
NOTE 1 Reclaiming procedures of gases can be done by either reclaiming the complete gas or by separating the
most valuable components from the gas.
Gas analysis techniques for checking the quality of the gas are described in this document.
It is the responsibility of the gas manufacturer and/or the electrical power equipment
manufacturer to provide sufficient information for safe handling of gases and to provide a risk
assessment. It is the responsibility of the user of the electrical power equipment to establish
appropriate health and safety practices and to determine the applicability of regulatory
limitations prior to use.
NOTE 2 If not otherwise specified in this document, concentration values (e.g. %, ppmv, µl/l) of gas components or
contaminants are given in volume fraction at 20 °C and 100 kPa. More information on temperature an
...