EN 60480:2004

STANDARDSmernice za preverjanje in ravnanje z žveplovim heksafluoridom (SF6) iz električne opreme in specifikacija za njegovo ponovno uporabo (IEC 60480:2004)Guidelines for the checking and treatment of sulfur hexafluoride (SF6) taken from electrical equipment and specification for its re-use (IEC 60480:2004)©
Standard je založil in izdal Slovenski inštitut za standardizacijo. Razmnoževanje ali kopiranje celote ali delov tega dokumenta ni dovoljenoReferenčna številkaSIST EN 60480:2005(en)ICS29.040.20

EUROPEAN STANDARD
EN 60480 NORME EUROPÉENNE EUROPÄISCHE NORM
December 2004 CENELEC European Committee for Electrotechnical Standardization Comité Européen de Normalisation Electrotechnique Europäisches Komitee für Elektrotechnische Normung
Central Secretariat: rue de Stassart 35, B - 1050 Brussels
© 2004 CENELEC - All rights of exploitation in any form and by any means reserved worldwide for CENELEC members.
Ref. No. EN 60480:2004 E
ICS 29.040.20; 29.130
English version
Guidelines for the checking and treatment of sulphur hexafluoride (SF6) taken from electrical equipment and specification for its re-use (IEC 60480:2004)
Lignes directrices relatives au contrôle
et au traitement de l'hexafluorure
de soufre (SF6) prélevé sur le matériel électrique et spécification en vue
de sa réutilisation (CEI 60480:2004)
Richtlinien für die Prüfung und Aufbereitung von Schwefelhexafluorid (SF6) nach Entnahme aus elektrischen Betriebsmitteln und Spezifikation für dessen Wiederverwendung (IEC 60480:2004)
This European Standard was approved by CENELEC on 2004-11-01. 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 Central Secretariat 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 Central Secretariat has the same status as the official versions.
CENELEC members are the national electrotechnical committees of Austria, Belgium, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom.

at national level by publication of an identical
national standard or by endorsement
(dop)
2005-08-01 – latest date by which the national standards conflicting
with the EN have to be withdrawn
(dow)
2007-11-01 Annex ZA has been added by CENELEC. __________ Endorsement notice The text of the International Standard IEC 60480:2004 was approved by CENELEC as a European Standard without any modification. In the official version, for Bibliography, the following note has to be added for the standard indicated:
ISO 14040 NOTE Harmonized as EN ISO 14040:1997 (not modified). __________

- 3 - EN 60480:2004
Annex ZA
(normative)
Normative references to international publications
with their corresponding European publications The following referenced documents are indispensable for the application 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 Where an international publication has been modified by common modifications, indicated by (mod), the relevant EN/HD applies. Publication Year Title EN/HD Year IEC 60050-191 1990 International Electrotechnical Vocabulary (IEV) Chapter 191: Dependability and quality of service
- - IEC 60050-212 1990 Chapter 212: Insulating solids, liquids and gases
- - IEC 60050-441 1984 Chapter 441: Switchgear, controlgear and fuses
- - IEC 60050-826 1982 Chapter 826: Electrical installations of buildings
- - IEC 60376 1971 Specification and acceptance of new sulphur hexafluoride
- - IEC 60376A 1973 First supplement - Section Thirteen: Mineral oil content
- - IEC 60376B 1974 Second supplement - Clause 26
- - IEC 60694 1996 Common specifications for high-voltage switchgear and controlgear standards
EN 60694 + Corr. May 1996 1999 IEC 61634 1995 High-voltage switchgear and controlgear – Use and handling of sulfur hexafluoride (SF6) in high-voltage switchgear and controlgear
- -
NORME INTERNATIONALECEIIEC INTERNATIONAL STANDARD 60480Deuxième éditionSecond edition2004-10 Lignes directrices relatives au contrôle et au traitement de l'hexafluorure de soufre (SF6) prélevé sur le matériel électrique et spécification en vue de sa réutilisation
Guidelines for the checking and treatment of sulfur hexafluoride (SF6) taken from electrical equipment and specification for its re-use
Pour prix, voir catalogue en vigueur For price, see current catalogue IEC 2004
Droits de reproduction réservés

Copyright - all rights reserved Aucune partie de cette publication ne peut être reproduite ni utilisée sous quelque forme que ce soit et par aucun procédé, électronique ou mécanique, y compris la photocopie et les microfilms, sans l'accord écrit de l'éditeur. No part of this publication may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from the publisher. International Electrotechnical Commission,
3, rue de Varembé, PO Box 131, CH-1211 Geneva 20, SwitzerlandTelephone: +41 22 919 02 11 Telefax: +41 22 919 03 00 E-mail: inmail@iec.ch
Web: www.iec.ch CODE PRIX PRICE CODE V Commission Electrotechnique InternationaleInternational Electrotechnical Commission

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CONTENTS FOREWORD.7 INTRODUCTION.11
1 Scope.13 2 Normative references.13 3 Terms and definitions.15 3.1 General terms.15 3.2 Material aspects.15 3.3 Environmental aspects.17 4 Typical applications of SF6.19 5 Impurities and their sources.19 5.1 Introductory remark.19 5.2 Impurities from handling and in service.19 5.3 Impurities in equipment having only an insulating function.19 5.4 Impurities in switching equipment.19 5.5 Impurities from internal arcs.21 6 Environmental aspects.21 6.1 Introductory remark.21 6.2 Impact on the ecosystem.21 6.3 Ozone depletion.21 6.4 Greenhouse effect.21 6.5 Decomposition products.21 6.6 Conclusion.21 7 Health and safety.23 7.1 Introductory remark.23 7.2 Precautions necessary with SF6.23 7.3 Necessary precautions with used SF6.23 7.4 Health considerations.25 8 Quality specification for re-use of SF6 in new or existing switchgear.25 8.1 Decision flowchart for SF6 removed from electrical equipment for treatment.25 8.2 Maximum acceptable impurity levels for re-use of SF6.29 9 Analytical methods for SF6 and their significance.29 9.1 General.29 9.2 On-site analysis.31 9.3 Laboratory analysis.33 10 Handling, storage and transportation.35 10.1 Introductory remark.35 10.2 Gas handling equipment.35 10.3 General safety requirements.35 10.4 Condition of the SF6 in an enclosure.37 10.5 Removing used SF6 from an enclosure.39 10.6 Storage and transportation of used SF6.39

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Annex A (informative) Derivation of maximum tolerable moisture levels for re-use.41 Annex B (informative) Description of the different methods of analysis (on-site and laboratory).45 Annex C (informative) Reclaiming recommendations and procedures on-site.61
Bibliography.67
Figure 1 – Decision flow chart for the destination of removed SF6.27 Figure 2 – Decision flow chart for on-site analysis.31 Figure A.1 – Moisture levels (ppmv) as a function of gas pressure p.41 Figure B.1 – SF6 gas sampling set-up: evacuation.45 Figure B.2 – SF6 gas sampling set-up: purging.47 Figure B.3 – Typical gas chromatogram of decomposed SF6.53 (analysis performed with a Porapak Q column).53 Figure B.4 – IR spectrum of contaminated SF6.59
Table 1 – Origin of SF6 impurities.19 Table 2 – Maximum acceptable impurity levels.29 Table 3 – On-site methods.33 Table 4 – Laboratory methods.33 Table B.1 – Thermal conductivity detector relative response factor.55 Table B.2 – Peak absorption of SF6 and contaminants.59 Table C.1 – Suggested reclaiming operations.61 Table C.2 – Typical adsorbents for various SF6 impurities.63 Table C.3 – Summary of SF6 transportation regulations.65

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INTERNATIONAL ELECTROTECHNICAL COMMISSION ____________
GUIDELINES FOR THE CHECKING AND TREATMENT OF SULFUR HEXAFLUORIDE (SF6) TAKEN FROM ELECTRICAL EQUIPMENT AND SPECIFICATION FOR ITS RE-USE
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 provides no marking procedure to indicate its approval and cannot be rendered responsible for any equipment declared to be in conformity with an IEC Publication. 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) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of patent rights. IEC shall not be held responsible for identifying any or all such patent rights.
International Standard IEC 60480 has been prepared by IEC technical committee 10: Fluids for electrotechnical applications. This second edition cancels and replaces the first edition, published in 1974, and constitutes a technical revision. The main changes with respect to the previous edition are listed below: • updating of standard as it relates to environmental issues, storage and analytical methods; • addition of specification for the re-use of gas; • inclusion of a regeneration process for sulfur hexafluoride taken from electrical equipment.

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The text of this standard is based on the following documents: FDIS Report on voting 10/611/FDIS 10/612/RVD
Full information on the voting for the approval of this standard can be found in the report on voting indicated in the above table. This publication has been drafted in accordance with the ISO/IEC Directives, Part 2. The committee has decided that the contents of this publication will remain unchanged until the maintenance result date indicated on the IEC web site under "http://webstore.iec.ch" in the data related to the specific publication. At this date, the publication will be
• reconfirmed; • withdrawn; • replaced by a revised edition, or • amended.

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INTRODUCTION Sulfur hexafluoride, SF6, is an essential gas for electrical equipment. Influenced by environ-mental concerns, the international community, and especially the electrical industry, has made and is still making a substantial contribution towards controlling the environmental impact of the product at all stages of its life, from “the cradle to the grave”, as it is defined in ISO 14040 [5] 1. In line with these efforts and as a complement to them, particular attention has been paid to reclaiming procedures of the SF6 as used in electrical equipment. These procedures allow the re-use of the gas when equipment is maintained, repaired or reaches the end of its service life. This includes acceptable limits for impurity levels, according to experience gained by main users (manufacturers and electrical utilities). ___________ 1 References in square brackets refer to the bibliography.

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GUIDELINES FOR THE CHECKING AND TREATMENT OF SULFUR HEXAFLUORIDE (SF6) TAKEN FROM ELECTRICAL EQUIPMENT AND SPECIFICATION FOR ITS RE-USE
1 Scope
This International Standard concerns the re-use of sulfur hexafluoride (SF6) after removal from electrical equipment (for maintenance, or at the end of life).
This standard recommends procedures for reclaiming used SF6 and for restoring its quality to an acceptable level, which would allow the filling of new or existing electrical equipment. This standard provides guidance to operational and maintenance personnel for the testing and safe handling of used SF6 . 2 Normative references The following referenced documents are indispensable for the application 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. IEC 60050(191):1990, International Electrotechnical Vocabulary (IEV) – Chapter 191: Dependability and quality of service IEC 60050(212):1990, International Electrotechnical Vocabulary (IEV) – Chapter 212: Insulating solids, liquids, gases IEC 60050(441):1984, International Electrotechnical Vocabulary (IEV) – Chapter 441: Switchgear, controlgear and fuses IEC 60050(826):1982, International Electrotechnical Vocabulary (IEV) – Chapter 826: Electrical installations of buildings IEC 60376:1971, Specification and acceptance of new sulfur hexafluoride IEC 60376A:1973, First supplement, Specification and acceptance of new sulfur hexafluoride – Section Thirteen: Mineral oil content
IEC 60376B:1974, Second supplement, Specification and acceptance of new sulfur hexafluoride – Clause 26 IEC 60694:1996, Common specifications for high-voltage switchgear and controlgear standards IEC 61634:1995, High-voltage switchgear and controlgear – Use and handling of sulfur hexafluoride (SF6) in high-voltage switchgear and controlgear

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3 Terms and definitions For the purposes of this document, the terms and definitions contained in IEC 60050(191) IEC 60050(212), IEC 60050(441) and IEC 60050(826), as well as the following, apply. 3.1 General terms 3.1.1 electrical equipment any item used for such purposes as generation, conversion, transmission, distribution or utilization of electrical energy, such as machines, transformers, apparatus, measuring instruments, protective devices, wiring materials, appliances
[IEV 826-07-01] 3.1.2 enclosure part providing protection of equipment against certain external influences and, in any direction, against direct contact
[IEV 826-03-12] 3.1.3 maintenance combination of all technical and administrative actions, including supervision actions, intended to retain an item in, or restore it to, a state in which it can perform a required function [IEV 191-07-01] 3.2 Material aspects 3.2.1 insulating material solid with negligible low electric conductivity, used to separate conducting parts of different electrical potentials
[IEV 212-01-01] 3.2.2 insulating gas gas with negligible low electric conductivity, used to separate conducting parts of different electrical potentials [IEV 212-01-03] 3.2.3 electrode conducting part intended as a conducting interface with a medium of different conductivity 3.2.4 reservoir storage container

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3.3 Environmental aspects
3.3.1 new sulfur hexafluoride SF6 complying with IEC 60376, and never used previously 3.3.2 used sulfur hexafluoride SF6 introduced into electrical equipment 3.3.3 unused sulfur hexafluoride SF6 never been introduced into electrical equipment (e.g. gas having been transferred into a storage tank) 3.3.4 recycling operation to pass through a series of changes or treatment so as to return to a previous stage in a cyclic process 3.3.5 reclaiming elimination of soluble and insoluble contaminants from an insulating liquid or gas by chemical adsorption means, in addition to mechanical means, in order to restore properties as close as possible to the original values or to the levels proposed in this standard [IEV 212-09-05, modified] 3.3.6 solid adsorbent solid substances that can be used for adsorbing impurities 3.3.7 reclaimer device for the purification of used gas for the purpose of re-use on-site [1] 3.3.8 re-use use of reclaimed gas for filling new or existing electrical equipment 3.3.9 reclaimed gas gas that has been processed by a reclaimer [1] 3.3.10 recovery transfer of gas from electrical power equipment into a reclaimer or storage container [1] 3.3.11 final disposal transformation of gas into substances which can either be used for other purposes or which can be disposed of in an environmentally compatible way [1]

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4 Typical applications of SF6 The typical applications of SF6 are described in IEC 60376 and IEC 61634. 5 Impurities and their sources 5.1 Introductory remark SF6 taken from electrical equipment in operation contains several kinds of impurities. Some of them are already present in the new gas, as a result of the manufacturing process. The nature of these impurities and the quantities admissible are reported in IEC 60376 and IEC 61634. The expected additional impurities in SF6 taken from equipment come from both gas handling and the operation of the equipment. Table 1 summarizes the main impurities and their sources [1][2].
Table 1 – Origin of SF6 impurities SF6 situation and use Sources of impurities Possible impurities During handling and in service Leaks and incomplete evacuation Desorption Air, Oil, H2O Insulating function
Partial discharges: Corona and sparking HF, SO2, SOF2, SOF4, SO2F2 Switching arc erosion
H2O, HF, SO2, SOF2, SOF4, SO2F2,CuF2, SF4, WO3, CF4, AlF3 Switching equipment Mechanical erosion
Metal dusts, particles Internal arc Melting and decomposition of materials Air, H2O, HF, SO2, SOF2, SOF4, SO2F2, SF4, CF4 Metal dusts, particles, AlF3, FeF3 WO3 CuF2
5.2 Impurities from handling and in service Filling and emptying equipment may lead to the addition of air and water vapour. Moisture can also be desorbed from internal surfaces of the equipment and from polymeric parts. Oil from handling equipment (pumps and compressors) may also be inadvertently introduced to SF6.
5.3 Impurities in equipment having only an insulating function The essential process is the decomposition of SF6 by partial discharges (corona and sparking). The immediate products are fragments of SF6, such as SF5, SF4 and F, that combine with O2 and H2O to form compounds, mainly HF, SO2, SOF2, SOF4 and SO2F2. Due to low energy of the partial discharges, the accumulated quantities of these compounds are usually negligible. 5.4 Impurities in switching equipment During current interruption, the existence of high temperature arcs leads to the formation of decomposition products of SF6, vaporized electrode metal, plastics and impurities. In addition, chemical reactions take place between the products formed (see Table 1).

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The quantity of these by-products is controlled by the number of operations, the design of equipment and the use of adsorbers (solid adsorbents). Switching equipment may also contain particles and metal dust coming from the rubbing of contacts.
5.5 Impurities from internal arcs The occurrence of an internal arc is extremely rare. The expected impurities in SF6 in faulted equipment are similar to those normally found in switching equipment. The difference lies in the quantity of compounds, which becomes high enough to create a potential toxic risk (see IEC 61634). In addition, significant vaporization of metallic material occurs and creates additional reaction products. 6 Environmental aspects 6.1 Introductory remark Human activities have an effect on the environment. The impact of a given activity depends on its scale and on the materials involved. It is therefore necessary to consider the possible influence of SF6 on the environment. 6.2 Impact on the ecosystem SF6 is an inert gas [3]. As its solubility in water is very low [3], it presents no danger to surface and ground water or the soil. A biological accumulation in the nutrition cycle does not occur. Therefore, SF6 does not harm the ecosystem. 6.3 Ozone depletion SF6 does not contribute to the destruction of stratospheric ozone [3]. 6.4 Greenhouse effect SF6 contributes to the greenhouse effect. However, the relative amounts used are such that its contribution is less than 1 to 1 000 in comparison with other agents. Its effect is very small. Good handling practices such as those defined in this standard contribute to ensuring that a very small impact is effectively maintained over a long period of time [3]. 6.5 Decomposition products Decomposition products of SF6 are not released into the atmosphere in significant quantities [2]. At the end of the service life of an item of equipment, they can be converted into naturally occurring neutral products with no adverse impact on the local environment. 6.6 Conclusion The use of SF6 in electrical equipment has a negligible impact on the global environment and ecosystem. However, this will only remain so provided that due regard is paid by users to the containment and management of SF6 when used in electrical equipment.

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7 Health and safety
7.1 Introductory remark SF6 is odourless, tasteless and colourless. It is chemically stable at room temperature and is non-combustible. In principle, a mixture of 20 % of oxygen and 80 % SF6 can be inhaled without adverse effect. However, it is generally recommended that the maximum concentration of SF6 in the working environment should be kept lower than 1 000 µl/l. This is the value accepted for a full time (8 h/day, 5 day/week) work schedule. This is not related to toxicity, but is an established limit for all non-toxic gases which are not normally present in the atmosphere. 7.2 Precautions necessary with SF6 In addition to the information given above, several simple precautions should be observed when SF6 gas is employed. The following are the main areas of importance. 7.2.1 Oxygen depletion SF6 gas is about 5 times heavier than air and if released in large quantities into the working environment may accumulate in low-lying areas. In doing so the air is displaced and consequently the quantity of available oxygen will fall. If the oxygen concentration falls below 16 % (see IEC 61634), a danger of asphyxiation will exist for any personnel working in these areas. Particularly sensitive areas are those below ground level, poorly or not ventilated, such as cable ducts, trenches, inspection pits and drainage systems. However, after a period of time and depending upon air movement and ventilation, the SF6 will become mixed with the working environment air and its local concentration will fall to acceptable levels. 7.2.2 Mechanical
In many applications the pressure of SF6 gas employed is above atmospheric pressure. This implies that special precautions have to be taken when handling the equipment, to avoid exposing workers to the risks associated with mechanical failure of the enclosure walls. 7.2.3 Freezing If compressed SF6 is released rapidly, the sudden expansion reduces its temperature. The gas temperature may fall to well below 0 °C. A worker accidentally subjected to a jet of gas, during equipment filling for example, runs a risk of serious freezing burns, if he is not equipped with protective clothing and eye protection. 7.3 Necessary precautions with used SF6 Under certain conditions, the SF6 gas used in electrical equipment can contain decomposition products with potential toxic properties. Decomposition can occur in two ways: electrical discharges and heating.

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7.3.1 Electrical discharge decomposition Any form of electrical sparking in SF6 gas will tend to break the molecule down into its constituent parts. Following this chemical breakdown however, the vast majority of the break-down products recombine back to SF6. As mentioned in Clause 5, the presence of oxygen and water vapour (and metal surfaces), render other reaction paths possible. Some of these paths lead to the appearance of small quantities of by-products, which may have toxic properties. 7.3.2 Thermal decomposition Above about 500 °C SF6 gas begins to break down into its constituent elements. Such temperatures may result, for example, from fires, heating elements, cigarette smoking, etc. The presence of metallic surfaces can enhance this effect through catalytic reactions. Decomposition products can appear by similar mechanisms to those cited in 7.3.1. 7.4 Health considerations
During normal service, the SF6 gas remains inside the electrical equipment and the stable toxic decomposition products are trapped by adsorbents or on the internal surfaces of the enclosure. SF6 can escape from the electrical equipment in three ways: • leakage; • inadequate handling procedures; • enclosure failure. A risk to health exists only if a sufficient quantity of the decomposition products are present in the working environment coupled with the exposure time. These situations are treated in detail in IEC 61634. 8 Quality specification for re-use of SF6 in new or existing switchgear 8.1 Decision flowchart for SF6 removed from electrical equipment for treatment As a guide for the operator, the following flowchart (Figure 1) defines the selection procedure to determine the best use of SF6 after removing it from equipment for potential treatment [1][2].

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Is gas known to
be pollution free? No Analysis Does the gas comply
with IEC 60480? Final disposalReclaim to
IEC 60376 or
IEC 60480 Yes Noyes No Yes SF6 from electrical equipmentNoNo Yes Storage
tank Reclaim Pre-filterIs SF6 reclaimable on-site? YesIs internal fault or
high pollution
suspected? Reclaiming or disposal
company or the SF6 manufacturer Is SF6 reclaimable? Re-useStorage
tankDo air and H20 comply with IEC 60480? YesNoRe-use IEC
1261/04 Figure 1 – Decision flow chart for the destination of removed SF6

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8.2 Maximum acceptable impurity levels for re-use of SF6
Table 2 – Maximum acceptable impurity levels Maximum acceptable levels Impurity Rated absolute pressure <200 kPa a Rated absolute pressure
>200 kPa a Air and/or CF4 3 % volume b
3 % volume b
H2O 95 mg/kg c,d
25 mg/kg d,e Mineral oil 10 mg/kg f
Total reactive gaseous decomposition products 50 µl/l total or 12 µl/l for (SO2+SOF2) or 25 µl/l HF a Within the complete range of re-use pressures, covering all possible applications (both HV and MV insulation systems as well as all circuit-breakers), the low re-use pressure range p < 200 kPa has been defined to highlight low pressure insulation systems (typically applied in MV distribution). b In the case of SF6 mixtures, the levels for these gases shall be specified by the equipment manufacturer. c 95 mg/kg (95 ppmw) is equivalent to 750 ppmv (750 µl/l) and to a dew point of –23 °C, measured at 100 kPa and 20 °C. d Converted to ppmv these levels shall also apply to mixtures until a suitable standard becomes available. e 25 mg/kg (25 ppmw) is equivalent to 200 ppmv (200 µl/l) and to a dew point of –36 °C, measured at 100 kPa and 20 °C. f If gas handling equipment (pump, compressor) containing oil is used, it may be necessary to measure the oil content of the SF6. If all equipment in contact with the SF6 is oil-free, then it is not necessary to measure oil content.
For the analysis, the sampling is a critical issue (see Clause B.1: Sampling). • For impurities of water or decomposition products, the question of whether the SF6 is reclaimable on-site depends only on the performance of the filters available. If the SF6 is not reclaimable on-site, then it shall be returned to the SF6 manufacturer or sent to a reclaiming or disposal company.
• The case of contamination with air and/or CF4 shall be considered separately. If the concentration of air and/or CF4 exceeds the maximum acceptable impurity level as given in Table 2, and if the reservoir from which the sample has been taken contains liquid SF6, then transfer SF6 from the gas phase into a second reservoir. The transfer should be continued until a sample from the first reservoir satisfies the maximum acceptable level. The contents of the second reservoir cannot be reclaimed on-site. Any reservoir that contains no liquid SF6, i.e. only the gas phase, requires the analysis of only one sample for air and CF4 to determine if it is suitable for re-use or cannot be reclaimed on-site.
9 Analytical methods for SF6 and their significance 9.1 General The methods for analysis of SF6 shall be used on gas samples. Details of the procedures for obtaining a sample and of the analytical methods are provided in Annex B.

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9.2 On-site analysis These methods are intended to be quick and simple for screening the gas. The order of analysis has been set to determine, as quickly as possible, if the gas is re-usable or reclaimable on-site (Figure 2).
SF6
analysis Is (SO2 + SOF2) >12 µl/l or HF> 25 µl/l? Re-use gas Reclaim gas Is water > values in Table 2? Is air or/and CF4 > 3 %? Is mineral oil >10 mg/kg? (See Table 2, foot note f) No No YesYesNo No YesYesIEC
1262/04
Figure 2 – Decision flow chart for on-site analysis If on-site analysis systems are available, the specification requires the use of the lowest possible amount of SF6, to avoid any release of SF6 to the atmosphere, and to ensure the health and safety of personnel. The order of the gas screening analysis and the on-site available analytical methods are shown respectively in Figure 2, Table 3 and Annex B.
For all on-site analysis, the operator shall follow the manufacturer’s instructions concerning the accuracy of analytical equipment.

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The analysis for SO2, SOF2 and HF are required first for two reasons: firstly for safety, to allow personnel to assess the risk involved in handling used SF6, and secondly to protect the analytical equipment against corrosion.
Table 3 – On-site methods Order of analysis Impurities Methods available a Decomposition products: SO2, SOF2, SO2F2
(See note)
Tube for SO2 + SOF2 Portable gas chromatograph with thermal conductivity detector (GC-TCD) 1 b HF Tube for HF 2
Air and CF4 Density meter (for the % of SF6) Portable GC-TCD 3
Water (moisture) Tube for water Electronic hygrometer Chilled mirror hygrometer Electrochemical sensor 4
Oil Tube for mineral oil NOTE SO2F2 may be present in the gas but cannot be measured with detector tubes. To ensure the removal of this by-product, see Annex C.
9.3 Laboratory analysis If no equipment is available on-site, the following recommended techniques shall be used. Laboratory methods are intended to provide a quantitative assessment of the impurities in a gas sample. Water is the only contaminant that cannot be determined accurately from a sampling cylinder. The water content of a sample in a cylinder taken from a reservoir is not representative of the water content in the reservoir because water adsorbs on all surfaces. Therefore, the water analysis should always be carried out directly on the reservoir on-site. There is no recom-mended order of analysis. Table 4 – Laboratory methods Impurities Methods available Air: oxygen and nitrogen Gas chromatograph with thermal conductivity detector (GC-TCD) CF4 Gas chromatograph (GC-TCD) Infrared absorption Oil Infrared absorption Gas chromatograph with flame ionization detector (GC-FID) Decomposition products: SO2, SOF2, SO2F2, SF4, HF Gas chromatograph (GC-TCD) Ion chromatography Infrared absorption

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10 Handling, storage and transportation
10.1 Introductory remark
Clause 10 deals with operations involving SF6 that has been in an electrical equipment enclosure and that may have been partially decomposed or contaminated. Such operations include removing and replacing the SF6 during maintenance or extension [2][3]. The need to handle used SF6 arises when a) the gas pressure is topped up in closed pressure systems, b) the gas has to be removed from an enclosure to allow for maintenance, repair or extension, c) the gas has to be removed at the end of the life of an item of equipment, d) samples of the gas need to be obtained, or the gas pressure measured, through temporary connection of a measuring device. Safety provisions in this clause are applicable to all these situations; the two first situations arise mainly with respect to high-voltage equipment and may occur with medium-voltage GIS equipment, in particular if it is required to extend an existing switchboard. They do not arise with equipment using sealed pressure systems. 10.2 Gas handling equipment When used SF6 has to be removed from an enclosure, caution shall be taken to prevent any avoidable release of the gas into the atmosphere and in particular into the work area. Gas recovery equipment shall be used wherever possible to allow the gas to be stored, usually under pressure. Such equipment should be capable of evacuating the enclosure to remove as much of the gas as possible. Gas recovery equipment is available which is specially designed for use with SF6 and is provided with reclaiming facilities for removing gaseous and solid decomposition products. This type of equipment is preferred, particularly for the removal of more heavily contaminated SF6, for example from circuit-breaker enclosures. 10.3 General safety requirements
Guidance for working safely with SF6 is required in order to anticipate the following hazards: a) oxygen depletion (see 7.2.1); b) freezing (see 7.2.3); c) exposure to decomposition products (see 7.3). Workers engaged in handling used SF6 shall be provided with personal safety equipment (gloves, safety glasses, etc.). The manufacturer’s instructions and user’s codes of practice shall specify which items of equipment are required for each situation listed in 10.1 (see IEC 61634). Workers handling used SF6 shall be familiar with the properties of SF6 decomposition products (Clause 5) and shall be aware of the risks to health (e.g. contact, inhalation, etc.) and the cautions necessary to minimize them. General safety recommendations are given in Clause 7 (see also IEC 61634).

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10.3.1 Training of workers Specific safety training shall be given to workers required to handle used SF6. It is not considered necessary that such workers have any pre-qualifying training or qualifications. Workers shall be trained in the use of SF6 handling equipment used to transfer gas from an enclosure into a storage vessel. The manufacturer's operating instructions for such equipment should be complied with whenever it is used. First-aid instructions shall be included in the safety training. 10.3.2 Facilities and services Where enclosures containing used SF6 have to be emptied and opened, adequate washing facilities for workers should be available. 10.3.3 Outdoor working When working outdoors, while removing used SF6 from an enclosure, no special precautions are necessary other than to prevent personnel from being exposed directly to its decomposition products, and to avoid release of SF6. 10.3.4 Indoor working Indoor installations should be provided with adequate ventilation. When used SF6 has to be removed from an enclosure in an indoor installation, it is necessary to ensure that the concentrations of potentially toxic decomposition products (e.g. HF, SO2, SOF2, SO2F2) remain at safe levels in the working area. Ideally, this is achieved by direct measurement of the concentrations of the main contributor to toxicity, thionyl fluoride SOF2, and of the products of SOF2 hydrolysis, sulfur dioxide SO2 and hydrogen fluoride HF. For a medium level of decomposition, safe levels of these compounds are indicated by a maximum concentration of 200 µl/l of SF6 in the area (see IEC 61634). Nevertheless, this should not preclude the more important concern: avoiding the release of SF6.
A notice stating that open fires, smoking, heating to more than 200 °C and welding without special precautions are prohibited and giving first-aid instructions (see IEC 61634) should be displayed while SF6 is being handled in an indoor location. 10.4 Condition of the SF6 in an enclosure
The condition of the used SF6 in an enclosure will depend on the types and energies of electrical discharges or arc that have occurred within it. Three situations are commonly found as follows: a) SF6 is in an enclosure which does not contain active parts of a circuit-breaker and that is not linked to a circuit-breaker enclosure so that an exchange of gas cannot occur.
Gas: zero to low decomposition.
Solids: little or no powder deposits.

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b) SF6 is in an enclosure containing active parts of a circuit-breaker, or linked to such a compartment.
Gas: medium decomposition (by-product contents depend on the efficiency of the absorbent material used in this type of enclosure).
Solids: quantity of deposits will depend upon the current interruption history. c) SF6 is in any enclosure in which abnormal arcing occurred but where the enclosure did not open to the atmosphere through pressure relief valve or burn-through. In this case, an internal fault has occurred but a circuit-breaker has cleared the fault before the pressure in the enclosure has risen sufficiently to cause a release of SF6.
Gas: high decomposition should be expected.
Solids: a large quantity of deposits is expected. Their compositions depend on which materials have been heated by the arc. Information on sampling and testing SF6 taken from an enclosure is given in Annex A. 10.5 Removing used SF6 from an enclosure
Gas recovery equipment, as described in Annex C, shall be provided to allow SF6 to be removed whilst minimizing leakage to the atmosphere, and will preferentially contain means for reclaim
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