EN IEC 62932-2-2:2020

Flow battery energy systems for stationary applications - Part 2-2: Safety requirements

IEC 62932-2-2:2020 applies to flow battery systems for stationary applications and their installations with a maximum voltage not exceeding 1 500 V DC in compliance with IEC 62932-1. This document defines the requirements and test methods for risk reduction and protection measures against significant hazards relevant to flow battery systems, to persons, property and the environment, or to a combination of them. This document is applicable to stationary flow battery systems intended for indoor and outdoor commercial and industrial use in non-hazardous (unclassified) areas. This document covers significant hazards, hazardous situations and events, with the exception of those associated with natural disaster, relevant to flow battery systems, when they are used as intended and under the conditions foreseen by the manufacturer including reasonably foreseeable misuse thereof. The requirements described in this document are not intended to constrain innovations. When considering fluids, materials, designs or constructions not specifically dealt with in this document, these alternatives are evaluated as to their ability to yield levels of safety equivalent to those specified in this document.

Flussbatterie-Systeme für stationäre Anwendungen – Teil 2-2: Sicherheitsanforderungen

Systèmes de production d’énergie de batteries d’accumulateurs à circulation d'électrolyte pour applications stationnaires – Partie 2-2: Exigences de sécurité

L’IEC 62932-2-2:2020 s’applique aux systèmes de batteries d’accumulateurs à circulation d’électrolyte pour les applications stationnaires et à leurs installations avec une tension maximale ne dépassant pas 1 500 V en courant continu conformément à l’IEC 62932-1. Le présent document définit les exigences et les méthodes d’essai pour la réduction du risque, ainsi que les mesures de protection contre les dangers significatifs, concernant les systèmes de batteries d’accumulateurs à circulation d’électrolyte, les personnes, les biens et l’environnement, ou une combinaison de ces facteurs. Le présent document est applicable aux systèmes de batteries d’accumulateurs à circulation d’électrolyte stationnaires destinés à une utilisation commerciale et industrielle à l’intérieur et à l’extérieur dans des emplacements (non classés) non dangereux. Le présent document couvre les dangers, ainsi que les situations et événements dangereux significatifs, à l’exception de ceux associés à une catastrophe naturelle, concernant les systèmes de batteries d’accumulateurs à circulation d’électrolyte, lorsqu’ils sont utilisés tel que prévu et dans les conditions prévues par le fabricant, y compris leur mauvaise utilisation raisonnablement prévisible. Les exigences décrites dans le présent document ne sont pas destinées à limiter les innovations. La prise en compte des fluides, matériaux, conceptions ou constructions dont le présent document ne traite pas particulièrement évalue ces variantes quant à leur capacité à produire des niveaux de sécurité équivalant à ceux spécifiés dans le présent document.

Sistemi pretočnih baterij za vgrajeno opremo - 2-2. del: Varnostne zahteve

General Information

• Status: Published
• Publication Date: 16-Apr-2020
• ICS: 29.220.99 - Other cells and batteries
• Technical Committee: CLC/TC 21X - Secondary cells and batteries
• Drafting Committee: IEC/TC 21 - IEC_TC_21
• Current Stage: 6060 - Document made available - Publishing
• Start Date: 17-Apr-2020
• Completion Date: 17-Apr-2020
• Ref Project: SIST EN IEC 62932-2-2:2020 - Flow Battery Systems for Stationary applications - Part 2-2: Safety requirements

Overview

EN IEC 62932-2-2:2020 (IEC 62932-2-2:2020) specifies safety requirements for flow battery energy systems for stationary applications. It applies to systems and installations with a maximum voltage not exceeding 1 500 V DC, intended for indoor and outdoor commercial and industrial use in non-hazardous (unclassified) areas, and is to be used in conjunction with IEC 62932-1 (terminology and general aspects). The standard defines requirements and test methods to reduce risks to persons, property and the environment, covering foreseeable use and misuse (excluding natural disasters) and encouraging equivalent safety solutions for novel designs and fluids.

Key Topics and Technical Requirements

• Risk analysis procedure: Mandatory assessment of significant hazards, hazardous situations and events related to flow battery systems.
• Electrical hazards: Requirements addressing electrical shock, short-circuits, leakage currents and protective electrical measures for systems up to 1 500 V DC.
• Gaseous emissions: Identification, venting and mitigation of harmful gas emissions; ventilation design and warning sign requirements.
• Liquid hazards and containment: Measures for electrolyte leakage detection, containment, flow-path identification and protective construction to prevent environmental and safety impacts.
• Mechanical hazards: Protection against moving parts and mechanical failures within system components and balance-of-plant.
• Operational safety: Requirements for safe start/stop sequences, remote monitoring and control, emergency stop functions, auxiliary power failure behavior, alarms and fault response.
• Marking and documentation: Nameplate data, warning labels, user manual content (recommended structure included as informative Annex A).
• Transport, storage, disposal: Packaging, dismantling, recycling and environmental considerations.
• Inspection, maintenance and verification tests: Defined verification testing (dielectric strength, operational sequence, emergency stop, protective measures) and acceptance criteria; specific safety requirements for stacks (Annex B).

Applications and Who Uses This Standard

• Manufacturers and designers of flow battery systems and electrochemical stacks
• System integrators and installation contractors for stationary energy storage
• Safety engineers, facility managers and operators of commercial/industrial energy systems
• Testing and certification laboratories performing verification tests and conformity assessments
• Regulators, procurement teams and consultants specifying safe grid-scale or behind-the-meter storage

Related Standards

• IEC 62932-1 (Terminology and general aspects)
• IEC 62485-2 (Safety requirements for stationary batteries)
• Relevant electrical installation and safety standards (e.g., IEC 60364 series, IEC 60079-10-1) and safety signage (ISO 7010)

EN IEC 62932-2-2:2020 is essential for ensuring that flow battery energy systems meet recognized safety requirements, supporting reliable deployment of stationary flow battery solutions in commercial and industrial settings.

Standards Content (Sample)

SLOVENSKI STANDARD
01-julij-2020
Sistemi pretočnih baterij za vgrajeno opremo - 2-2. del: Varnostne zahteve
Flow Battery Systems for Stationary applications - Part 2-2: Safety requirements
Ta slovenski standard je istoveten z: EN IEC 62932-2-2:2020
ICS:
29.220.99 Drugi členi in baterije Other cells and batteries
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EUROPEAN STANDARD EN IEC 62932-2-2

NORME EUROPÉENNE
EUROPÄISCHE NORM
April 2020
ICS 29.220.99
English Version
Flow battery energy systems for stationary applications - Part 2-
2: Safety requirements
(IEC 62932-2-2:2020)
Systèmes de production d’énergie de batteries Flussbatterie-Systeme für stationäre Anwendungen - Teil 2-
d’accumulateurs à circulation d'électrolyte pour applications 2: Sicherheitsanforderungen
stationnaires - Partie 2-2: Exigences de sécurité (IEC 62932-2-2:2020)
(IEC 62932-2-2:2020)
This European Standard was approved by CENELEC on 2020-03-24. 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,
Turkey 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
© 2020 CENELEC All rights of exploitation in any form and by any means reserved worldwide for CENELEC Members.
Ref. No. EN IEC 62932-2-2:2020 E

European foreword
The text of document 21/1029/FDIS, future edition 1 of IEC 62932-2-2, prepared by IEC/TC 21
"Secondary cells and batteries" was submitted to the IEC-CENELEC parallel vote and approved by
CENELEC as EN IEC 62932-2-2:2020.
The following dates are fixed:
• latest date by which the document has to be implemented at national (dop) 2020-12-24
level by publication of an identical national standard or by endorsement
• latest date by which the national standards conflicting with the (dow) 2023-03-24
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.
Endorsement notice
The text of the International Standard IEC 62932-2-2:2020 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 standards
indicated:
IEC 60529 NOTE Harmonized as EN 60529
IEC 60664-1 NOTE Harmonized as EN 60664-1
IEC 60721-3-2 NOTE Harmonized as EN IEC 60721-3-2
IEC 60812 NOTE Harmonized as EN IEC 60812
IEC 60900 NOTE Harmonized as EN IEC 60900
IEC 61000 (series) NOTE Harmonized as EN 61000 (series)
IEC 61025 NOTE Harmonized as EN 61025
IEC 61660-1 NOTE Harmonized as EN 61660-1
IEC 61660-2 NOTE Harmonized as EN 61660-2
IEC 61936-1 NOTE Harmonized as EN 61936-1
IEC 62282-3-100 NOTE Harmonized as EN 62282-3-100
IEC 62282-3-300 NOTE Harmonized as EN 62282-3-300
IEC 62351 (series) NOTE Harmonized as EN 62351 (series)
IEC 62477-1 NOTE Harmonized as EN 62477-1
IEC 62932-2-1 NOTE Harmonized as EN IEC 62932-2-1
ISO 13850 NOTE Harmonized as EN ISO 13850

To be published. Stage at the time of publication: FprEN IEC 62932-2-1:2019.
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.cenelec.eu.
Publication Year Title EN/HD Year
IEC 60079-10-1 - Explosive atmospheres - Part 10-1: EN 60079-10-1 -
Classification of areas - Explosive gas
atmospheres
IEC 60364-4-41 - Low-voltage electrical installations - Part 4-41: HD 60364-4-41 -
Protection for safety - Protection against
electric shock
IEC 60364-4-43 - Low-voltage electrical installations - Part 4-43: HD 60364-4-43 -
Protection for safety - Protection against
overcurrent
IEC 60364-6 - Low voltage electrical installations - Part 6: HD 60364-6 -
Verification
IEC 61936-1 - Power installations exceeding 1 kV a.c. - Part EN 61936-1 -
1: Common rules
IEC 62485-2 2010 Safety requirements for secondary batteries EN IEC 62485-2 2018
and battery installations - Part 2: Stationary
batteries
IEC 62932-1 - Flow battery energy systems for stationary - -
applications - Part 1: Terminology and general
aspects
ISO 7010 - Graphical symbols - Safety colours and safety - -
signs - Registered safety signs

IEC 62932-2-2 ®
Edition 1.0 2020-02
INTERNATIONAL
STANDARD
Flow battery energy systems for stationary applications –

Part 2-2: Safety requirements
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 29.220.99 ISBN 978-2-8322-7854-3

– 2 – IEC 62932-2-2:2020 © IEC 2020
CONTENTS
FOREWORD . 5
INTRODUCTION . 7
1 Scope . 8
2 Normative references . 8
3 Terms, definitions and abbreviated terms . 9
3.1 Terms and definitions . 9
3.2 Abbreviated terms . 9
4 Procedure of the risk analysis . 9
5 Safety requirements and protective measures . 10
5.1 General . 10
5.2 Risk information . 10
5.3 Electrical hazards . 10
5.3.1 Electrical shock . 10
5.3.2 Short-circuits . 10
5.3.3 Leakage currents . 11
5.4 Hazards of gaseous emissions . 11
5.4.1 General . 11
5.4.2 Harmful gas . 12
5.4.3 Ventilation . 13
5.4.4 Warning sign . 13
5.4.5 Close vicinity to emissions . 14
5.5 Hazard posed by liquids . 14
5.5.1 General . 14
5.5.2 Detection of electrolyte leakage . 14
5.5.3 Protective measures against leakage . 14
5.5.4 Specific information . 14
5.5.5 Flow path identification . 15
5.6 Hazards of mechanical cause . 15
5.7 Operational hazards and measures . 15
5.7.1 General . 15
5.7.2 Start . 15
5.7.3 Remote monitoring and control systems . 16
5.7.4 Protection . 16
5.7.5 Auxiliary power failure . 16
6 Instructions . 16
7 Identification labels or marking . 16
7.1 Name plate information . 16
7.2 Warning label information and location . 17
8 Transport, storage, disposal and environmental aspects . 17
8.1 Packing and transport . 17
8.2 Dismantling, disposal, and recycling . 17
9 Inspection . 17
10 Maintenance . 18
11 Verification tests for protective measures . 18

IEC 62932-2-2:2020 © IEC 2020 – 3 –
11.1 General . 18
11.1.1 Tests . 18
11.1.2 Test object . 19
11.1.3 Test category . 19
11.2 Dielectric strength of the parts in contact with the fluid . 19
11.2.1 Requirements . 19
11.2.2 Category . 19
11.2.3 Number of samples . 19
11.2.4 Test and acceptance criteria . 19
11.3 Operational sequence . 19
11.3.1 Requirements . 19
11.3.2 Category . 19
11.3.3 Number of samples . 19
11.3.4 Test . 20
11.3.5 Acceptance criteria . 20
11.4 Emergency stop . 20
11.4.1 Requirement . 20
11.4.2 Category . 20
11.4.3 Number of samples . 20
11.4.4 Test . 20
11.4.5 Acceptance criteria . 20
11.5 Protection . 20
11.5.1 Requirements . 20
11.5.2 Category . 21
11.5.3 Number of samples . 21
11.5.4 Test . 21
11.5.5 Acceptance criteria . 21
11.6 Safety requirement for stacks . 21
Annex A (informative) Recommended structure of user manual . 22
A.1 General . 22
A.2 Table of contents . 22
A.3 Safety warning . 22
A.4 Introduction . 22
A.5 Product description . 22
A.5.1 Overview . 22
A.5.2 Technical specifications . 23
A.5.3 System structure. 23
A.5.4 Applications . 23
A.5.5 Operational sequence . 23
A.6 Site requirements . 23
A.6.1 Location and load . 23
A.6.2 Access and clearance . 23
A.6.3 Precautionary measures for fluid containment. 23
A.6.4 Ventilation . 24
A.6.5 Temperature . 24
A.7 Operation . 24
A.7.1 General . 24
A.7.2 Checks before operation . 24
A.7.3 Energizing and de-energizing the system . 24

– 4 – IEC 62932-2-2:2020 © IEC 2020
A.7.4 Valve status . 24
A.7.5 Specific operations . 24
A.7.6 Notices for operation . 24
A.8 Alarms and fault finding . 25
A.9 Maintenance . 25
A.10 Contact information . 25
Annex B (normative) Safety requirements for stacks . 26
B.1 General . 26
B.2 External short-circuit of the stack . 26
B.2.1 Requirements . 26
B.2.2 Category . 26
B.2.3 Number of samples . 26
B.2.4 Test . 26
B.2.5 Acceptance criteria . 26
B.3 Heat shock strength . 27
B.3.1 Requirements . 27
B.3.2 Category . 27
B.3.3 Number of samples . 27
B.3.4 Test . 27
B.3.5 Acceptance criteria . 27
B.4 Leakage of the stack . 27
B.4.1 Requirements . 27
B.4.2 Category . 28
B.4.3 Number of samples . 28
B.4.4 Test . 28
B.4.5 Acceptance criteria . 28
Bibliography . 29

Figure 1 – Flow battery energy system . 7

Table 1 – List of verification tests for protective measurements . 18
Table B.1 – List of verification tests for stacks for protective measurements . 26

IEC 62932-2-2:2020 © IEC 2020 – 5 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
FLOW BATTERY ENERGY SYSTEMS FOR STATIONARY APPLICATIONS –

Part 2-2: Safety requirements
FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
all national electrotechnical committees (IEC National Committees). The objective 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. 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 edition.
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 62932-2-2 has been prepared by IEC technical committee 21:
Secondary cells and batteries, in collaboration with IEC technical committee 105: Fuel cell
technologies.
The text of this International Standard is based on the following documents:
FDIS Report on voting
21/1029/FDIS 21/1035/RVD
Full information on the voting for the approval of this International Standard can be found in the
report on voting indicated in the above table.
This document has been drafted in accordance with the ISO/IEC Directives, Part 2.
A list of all parts in the IEC 62932 series, published under the general title Flow battery energy
systems for stationary applications, can be found on the IEC website.

– 6 – IEC 62932-2-2:2020 © IEC 2020
The committee has decided that the contents of this document will remain unchanged until the
stability date indicated on the IEC website under "http://webstore.iec.ch" in the data related to
the specific document. At this date, the document will be
• reconfirmed
• withdrawn
• replaced by a revised edition, or
• amended.
IEC 62932-2-2:2020 © IEC 2020 – 7 –
INTRODUCTION
A flow battery system (FBS) can be utilized in a flow battery energy system (FBES). Such an
FBES can consist of:
– a flow battery system,
– a power conversion system,
– other equipment and surroundings.
The FBES is connected to the external power input/output via a point of connection (POC).
This document covers the domain of the FBES, as shown in Figure 1. Energy to the auxiliary
systems such as the battery management system (BMS), the battery support system (BSS),
and the power conversion system (PCS) may be supplied by one of the following:
a) direct connection to the external power source;
b) the internal power source of the FBES or FBS itself.

Figure 1 – Flow battery energy system

– 8 – IEC 62932-2-2:2020 © IEC 2020
FLOW BATTERY ENERGY SYSTEMS FOR STATIONARY APPLICATIONS –

Part 2-2: Safety requirements
1 Scope
This part of IEC 62932 applies to flow battery systems for stationary applications and their
installations with a maximum voltage not exceeding 1 500 V DC in compliance with
IEC 62932-1.
This document defines the requirements and test methods for risk reduction and protection
measures against significant hazards relevant to flow battery systems, to persons, property and
the environment, or to a combination of them.
This document is applicable to stationary flow battery systems intended for indoor and outdoor
commercial and industrial use in non-hazardous (unclassified) areas.
This document covers significant hazards, hazardous situations and events, with the exception
of those associated with natural disaster, relevant to flow battery systems, when they are used
as intended and under the conditions foreseen by the manufacturer including reasonably
foreseeable misuse thereof.
The requirements described in this document are not intended to constrain innovations. When
considering fluids, materials, designs or constructions not specifically dealt with in this
document, these alternatives are evaluated as to their ability to yield levels of safety equivalent
to those specified in this document.
2 Normative references
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.
IEC 60079-10-1, Explosive atmospheres – Part 10-1: Classification of areas – Explosive gas
atmospheres
IEC 60364-4-41, Low-voltage electrical installations – Part 4-41: Protection for safety –
Protection against electric shock
IEC 60364-4-43, Low-voltage electrical installations – Part 4-43: Protection for safety –
Protection against overcurrent
IEC 60364-6, Low voltage electrical installations – Part 6: Verification
IEC 61936-1, Power installations exceeding 1 kV a.c. – Part 1: Common rules
IEC 62485-2:2010, Safety requirements for secondary batteries and battery installations –
Part 2: Stationary batteries
IEC 62932-1, Flow battery energy systems for stationary applications – Part 1: Terminology and
general aspects
ISO 7010, Graphical symbols – Safety colours and safety signs – Registered safety signs

IEC 62932-2-2:2020 © IEC 2020 – 9 –
3 Terms, definitions and abbreviated terms
3.1 Terms and definitions
For the purposes of this document, the terms and definitions given in IEC 62932-1 apply.
ISO and IEC maintain terminological databases for use in standardization at the following
addresses:
• IEC Electropedia: available at http://www.electropedia.org/
• ISO Online browsing platform: available at http://www.iso.org/obp
3.2 Abbreviated terms
BMS battery management system
BSS battery support system
EES electrical energy storage
FBES flow battery energy system
FBS flow battery system
FMEA failure mode and effects analysis
FTA fault tree analysis
GHS global harmonized system
HAZOP hazard and operability study
MSDS material safety data sheet
PCS power conversion system
POC point of connection
SDS safety data sheet
UPS uninterruptible power system
4 Procedure of the risk analysis
A written risk analysis shall be performed on an FBES to ensure that:
a) all reasonably foreseeable hazards and hazardous events, including reasonably
foreseeable misuse throughout the anticipated lifetime, have been identified;
b) the risk for each of these hazards has been estimated from the combination of its probability
of occurrence and of its foreseeable severity;
c) the two factors which determine each one of the estimated risks (probability and severity)
have been eliminated or reduced to a level not exceeding the acceptable risk level as far
as reasonably possible according to the following principles in the order given:
– eliminate hazards or reduce risks by inherent design measures,
– take necessary protective measures in relation to risks that cannot be reduced by
inherent design measures,
– inform intended users and where appropriate other persons of the residual risks, indicate
whether any particular training is required and specify any need to use personal
protective equipment.
For example, failure mode and effects analysis (FMEA), fault tree analysis (FTA) methods,
hazard and operability study (HAZOP), and/or the following International Standards shall be
used as guidance:
• IEC 60812;
• IEC 61025.
– 10 – IEC 62932-2-2:2020 © IEC 2020
5 Safety requirements and protective measures
5.1 General
Each secondary battery has a different structure and therefore only the features critical or
specific to the flow battery shall be taken into consideration. The flow battery energy system as
shown in Figure 1 differs from other secondary batteries, in that a system for circulating the
electrolyte is present. The fluid circulating system consists of tanks, pumps, piping, sensors
and some safety-relevant devices.
From a chemical safety point of view, since fluid is contained in tanks, pipes and stacks, the
sealing is an important factor. There is also the possibility of hazardous gases being present,
requiring that appropriate countermeasures be implemented.
Clause 5 specifies the safety requirements and protective measures in consideration of the
above-mentioned aspects.
5.2 Risk information
The manufacturer shall provide the user with risk information based on the risk analysis to
describe hazards and the appropriate measures taken or to be taken for mitigation purposes.
The information shall include a safety data sheet (SDS).
The information can be provided in the form of a user manual. See the recommended structure
for user manual in Annex A.
5.3 Electrical hazards
5.3.1 Electrical shock
The FBS is an electrical energy storage device and contains hazardous live parts of DC and/or
AC voltage which can cause a risk of electrical shock. Electrolyte is to be considered as carrying
dangerous voltages.
Batteries are sources of dangerous voltages and energy (current flow) also when they are not
connected to an external power circuit. In flow batteries the amount of residual energy is, when
no electrolyte circulates, limited to the charge stored in the electrolyte remaining in the stack
itself. In all cases protective measures according to IEC 60364-4-41 shall be implemented.
5.3.2 Short-circuits
The electrical energy stored in an FBS can be released in an inadvertent and uncontrolled
manner due to short-circuiting the terminals. Because of its considerable level of energy and
subsequent high current, the heat generated can melt metal, produce sparks, cause explosion,
or vaporize fluid.
To avoid short-circuits, protective devices such as insulation shrouds, fuses and circuit breakers
shall be installed in a way that a short-circuit does not occur under any foreseeable conditions.
For the type of conductor arrangement of unprotected sections, IEC 60364-4-43 shall be taken
into consideration.
For protective measures, the FBS shall mitigate a short-circuit fault which occurs outside stacks
by:
– stopping the supply of energy and fluids to the flow battery cells;
– stopping PCS and opening circuit breaker(s); and,
– interrupting the short-circuit current path by using fuses between stacks.

IEC 62932-2-2:2020 © IEC 2020 – 11 –
It is suggested that each stack has a fuse to break the short-circuit path. Specific location and
quantity of fuses and/or circuit breakers shall be agreed and decided between the manufacturer
and the system user in consideration of cell protection and system safety.
The intrinsic safety of the stack under short-circuit conditions shall be verified according to
Annex B.
5.3.3 Leakage currents
In a system in which no point of the battery installation is directly connected to earth, ground
faults in the FBS are, due to the large amount of fluid in the fluid handling parts (pumps, pipes,
stacks, tanks), a particular problem, and system operators shall be well informed of this matter.
Ground faults can cause the following significant risks:
– electrocution when a person accesses the fluid leaking from piping, cells and/or other
components of the fluid system;
NOTE 1 In this case a person's body becomes a part of the circuit of the leakage current.
– arcs and fire when short-current is established by the fluid leaking from piping, cells and/or
other components of the fluid system.
NOTE 2 The criticality of arcs and fire depend on the electrical conductivity of the fluid. If the fluid has low electrical
conductivity, leakage current is small and severity of the risk is low. This also depends on the configuration of stacks.
Thus, the detection level is designed taking dangerous leakage current level into account.
The circuit of the FBS shall be properly insulated from other local conductive parts. The
minimum insulation resistance between the battery circuit and other local conductive parts shall
meet the requirements of IEC 62485-2:2010, 6.4. The minimum insulation resistance between
them shall be greater than 100 Ω per volt of the nominal voltage of the FBS.
The insulation shall resist the environmental effects of temperature, dampness, dust, gases,
steam, and mechanical stress.
Before carrying out any test, the absence of hazardous voltage between the battery and the
associated rack or enclosure shall be verified.
The battery shall be isolated from the external circuit before an insulation-to-ground resistance
determination test is carried out.
The insulation shall be verified in accordance with the test method in 11.2.
Protective devices for detecting grounding faults shall be provided in the FBS or in the external
system, such as a power conversion system, in order to account for a malfunction in the
insulation.
5.4 Hazards of gaseous emissions
5.4.1 General
Flow batteries can produce gases that can be explosive (hydrogen), toxic (bromine), or
corrosive, or that can affect the respiratory system. The quantities produced depend on the
operating conditions of the FBS and their release to the environment shall be managed with
adequate safety features (e.g. ventilation, absorption traps, scrubbers, voltage limits).
In general, gases are produced in the stacks and accumulated in the system. For example, in
the case of the FBS, gases are accumulated in the top portion of the tanks.
Since gas generation and accumulation depend on the characteristics and construction of
individual FBS, the gas hazard presents different levels of risk in individual FBS.

– 12 – IEC 62932-2-2:2020 © IEC 2020
When hydrogen is produced in an FBS, for example, the generation rate of hydrogen increases
as the FBS is charged above the rated voltage range. The correlation between the charging
voltage and the gas generation cannot be expressed by a common equation, however, because
the gas generation rate depends highly on the characteristics of cell components and fluids
which can vary between manufacturers.
The gas emission and its mitigation shall be considered in the flow battery design process. It is
suggested to install necessary gas monitoring equipment with alarms and appropriate interlocks.
5.4.2 Harmful gas
5.4.2.1 Explosive gas
The risk level of explosive gases increases if the following hazards coincide:
– generation and accumulation of combustible gases,
– their mixture with oxygen,
– presence of ignition sources.
The FBS shall have protective measures against the above hazards, including but not limited
to:
– reduction in the generation of combustible gases,
– dilution of combustible gases,
– prevention of diffusion of gases outside the volume where they are generated,
– elimination of ignition sources,
– prevention of external oxygen ingress.
5.4.2.2 Toxic gas
The risks caused by toxic gases increase if the following hazards coincide:
– generation and accumulation of toxic gases,
– human access to the vicinity of toxic gases.
The FBS shall have protective measures against the above hazards, including but not limited
to:
– elimination of toxic gases,
– dilution of toxic gases,
– collection of toxic gases by a scrubber,
– limitation of human access.
5.4.2.3 Corrosive gas
The risk level of corrosive gases increases if the following hazards coincide:
– generation and accumulation of corrosive gases,
– human access to the vicinity of corrosive gases.
The FBS shall have protective measures against the above hazards, including but not limited
to:
– construction of the system with corrosion-resistant material,
– elimination of corrosive gases,
– dilution of corrosive gases,
– collection of corrosive gases by a scrubber,
– limitation of human access.
IEC 62932-2-2:2020 © IEC 2020 – 13 –
5.4.2.4 Gases affecting the respiratory system
There are cases where gases affecting the respiratory system are generated and accumulated.
The risks caused by gases increase if the following hazards coincide:
– generation and accumulation of gases affecting the respiratory system,
– human access to the vicinity of gases affecting the respiratory system.
The flow battery system shall have protective measures against the above hazards, including
but not limited to:
– elimination of gases affecting the respiratory system,
– dilution of gases affecting the respiratory system,
– collection of gases affecting the respiratory system by a scrubber,
– limitation of human access.
5.4.3 Ventilation
5.4.3.1 General
The manufacturer shall specify the ventilation requirements for the room where the FBS is
installed. This specification shall involve warning signs, operator access limitation, mitigation
of static discharges, numbers of air exchanges in m /h, required air flow patterns and exhaust
direction. When the FBS is installed outdoors, the safety requirements and procedures for
approaching personnel shall be specified. The manufacturer shall provide data and a
measurement method used to determine the gas emission rating, and ventilation measures shall
be implemented based on IEC 60079-10-1. Reference shall be made to the theoretical minimum
ventilation flow rate to dilute the gases, which is given in IEC 60079-10-1.
Ventilation is required to ensure that no combustible or harmful gases reach a critical
concentration level. The ventilation requirement shall be met by either one or a combination of
the following methods:
– natural ventilation,
– forced ventilation through the room or enclosure.
5.4.3.2 Natural ventilation
When natural ventilation is used, battery rooms or enclosures shall be equipped with an inlet
and an outlet for the air with a minimum free opening area which meets the ventilation
requirements.
5.4.3.3 Forced ventilation
When forced ventilation is used, gases which are released from the FBS into the room or
enclosure shall be expelled to the atmosphere using a ventilation system, which may combine
an opening and fan. If forced ventilation is essential for the safe operation of the FBS, then an
appropriate interlock shall prevent its operation when the forced ventilation is not operating or
has failed.
5.4.4 Warning sign
Appropriate warning signs which prohibit sparks, smoking, open flame, and electrostatic
discharges shall be placed at the entrance of the hazardous area as determined in accordance
with IEC 60079-10-1.
– 14 – IEC 62932-2-2:2020 © IEC 2020
5.4.5 Close vicinity to emissions
The dilution of gases is not always fully achieved in the close vicinity of the exhaust of released
gases or at the outlet of direct forced ventilation, therefore a safety distance from the outlet
shall be observed. The dispersion of gases depends on the gas emission rate and the type of
ventilation close to the source of emission.
5.5 Hazard posed by liquids
5.5.1 General
The impact of the fluid involved in the FBS leakage can be categorized in terms of toxicity,
corrosiveness, en
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