ISO/FDIS 23273-2

FINAL
INTERNATIONAL ISO/FDIS
DRAFT
STANDARD 23273-2
ISO/TC 22/SC 21
Fuel cell road vehicles — Safety
Secretariat: DIN
specifications —
Voting begins on:
2013-03-08
Part 2:
Voting terminates on:
Protection against hydrogen hazards
2013-05-08
for vehicles fuelled with compressed
hydrogen
Véhicules routiers alimentés par pile à combustible — Spécifications
de sécurité —
Partie 2: Protection contre les dangers de l’hydrogène pour les
véhicules utilisant de l’hydrogène comprimé
RECIPIENTS OF THIS DRAFT ARE INVITED TO
SUBMIT, WITH THEIR COMMENTS, NOTIFICATION
OF ANY RELEVANT PATENT RIGHTS OF WHICH
THEY ARE AWARE AND TO PROVIDE SUPPOR TING
DOCUMENTATION.
IN ADDITION TO THEIR EVALUATION AS
Reference number
BEING ACCEPTABLE FOR INDUSTRIAL, TECHNO-
ISO/FDIS 23273-2:2013(E)
LOGICAL, COMMERCIAL AND USER PURPOSES,
DRAFT INTERNATIONAL STANDARDS MAY ON
OCCASION HAVE TO BE CONSIDERED IN THE
LIGHT OF THEIR POTENTIAL TO BECOME STAN-
DARDS TO WHICH REFERENCE MAY BE MADE IN
©
NATIONAL REGULATIONS. ISO 2013

---------------------- Page: 1 ----------------------
ISO/FDIS 23273-2:2013(E)

COPYRIGHT PROTECTED DOCUMENT
© ISO 2013
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized otherwise in any form
or by any means, electronic or mechanical, including photocopying, or posting on the internet or an intranet, without prior
written permission. Permission can be requested from either ISO at the address below or ISO’s member body in the country of
the requester.
ISO copyright office
Case postale 56 • CH-1211 Geneva 20
Tel. + 41 22 749 01 11
Fax + 41 22 749 09 47
E-mail copyright@iso.org
Web www.iso.org
Published in Switzerland
ii © ISO 2013 – All rights reserved

---------------------- Page: 2 ----------------------
ISO/FDIS 23273-2:2013(E)

Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out
through ISO technical committees. Each member body interested in a subject for which a technical
committee has been established has the right to be represented on that committee. International
organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.
ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of
electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2. www.iso.org/directives
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received. www.iso.org/patents
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
The committee responsible for this document is ISO/TC 22, Road vehicles, Subcommittee SC 21,
Electrically propelled road vehicles.
This second edition cancels and replaces the first edition (ISO 23273-2:2006), of which it constitutes a
minor revision.
ISO 23273 consists of the following parts, under the general title Fuel cell road vehicles — Safety
specifications:
— Part 2: Protection against hydrogen hazards for vehicles fuelled with compressed hydrogen
© ISO 2013 – All rights reserved iii

---------------------- Page: 3 ----------------------
FINAL DRAFT INTERNATIONAL STANDARD ISO/FDIS 23273-2:2013(E)
Fuel cell road vehicles — Safety specifications —
Part 2:
Protection against hydrogen hazards for vehicles fuelled
with compressed hydrogen
1 Scope
This part of ISO 23273 specifies the essential requirements for fuel cell vehicles (FCV) with respect to the
protection of persons and the environment inside and outside the vehicle against hydrogen-related hazards.
It applies only to such FCV where compressed hydrogen is used as fuel for the fuel cell system.
This part of ISO 23273 does not apply to manufacturing, maintenance, and repair.
The requirements of this part of ISO 23273 address both normal operating (fault-free) and single-fault
conditions of the vehicles.
2  Normative references
The following documents, in whole or in part, are normatively referenced in this document and are
indispensable for its application. For dated references, only the edition cited applies. For undated
references, the latest edition of the referenced document (including any amendments) applies.
ISO 17268, Gaseous hydrogen land vehicle refuelling connection devices
ISO 6469-1, Electrically propelled road vehicles — Safety specifications — Part 1: On-board rechargeable
energy storage system (RESS)
3  Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
air processing system
system that processes (i.e. that filters, meters, conditions, and pressurizes) the incoming air for the
fuel cell system
3.2
contaminant
substances within raw fuel, such as sulphur, that, at or above a specified concentration level, may poison
reaction catalysts
3.3
electric chassis
conductive mechanical structure of the vehicle, including all associated electric and electronic
components, whose parts are electrically connected and whose potential is taken as reference
3.4
excess flow valve
valve which automatically shuts off or limits the gas flow when the flow exceeds a set design value
© ISO 2013 – All rights reserved 1

---------------------- Page: 4 ----------------------
ISO/FDIS 23273-2:2013(E)

3.5
fuel cell
electrochemical device that generates electricity by the conversion of fuel and an oxidant without any
physical or chemical consumption of the electrodes or electrolyte
3.6
fuel cell stack
assembly of two or more fuel cells, which are electrically connected
3.7
fuel cell system
system typically containing the following subsystems: fuel cell stack, air processing system, fuel
processing system, thermal management, water management, and their control system
3.8
fuel cell vehicle
FCV
vehicle that receives propulsion power from an on-board fuel cell power system
Note 1 to entry: The general term FCV also includes vehicles with an additional other source of propulsion power.
3.9
fuel processing system
system that converts (if necessary) and/or conditions the fuel as stored in the on-board fuel storage into
fuel suitable for operation in the fuel cell stack
3.10
fuel system
combination of the on-board fuel storage, the fuel processing system, and the fuel cell stack
3.11
main hydrogen shut-off valve
valve designed to automatically isolate the high-pressure hydrogen source
3.12
maximum allowable working pressure
MAWP
maximum working pressure at which a component or system may be normally operated without damage,
including leakage and deformation
Note 1 to entry: The maximum allowable working pressure is used in determining the setting of
pressure-limiting/relieving devices installed to protect the part or system from accidental over-pressurizing.
3.13
nominal working pressure
pressure level at which a component typically operates
Note 1 to entry: For fuel containers, it is the settled pressure at a uniformed temperature of 15 °C (288 K) for a
full fuel container.
3.14
purge
process to eliminate unwanted gas constituents from the hydrogen system
3.15
temperature-triggered pressure relief device
PRD
excessive temperature-triggered, activated non-reclosing resealing device which vents gas to protect
the fuel container from rupture when subjected to a standard fire test
2 © ISO 2013 – All rights reserved

---------------------- Page: 5 ----------------------
ISO/FDIS 23273-2:2013(E)

4  Environmental and operational conditions
The requirement given in this part of ISO 23273 shall be met across the range of environmental
and operational conditions for which the vehicle is designed to operate, as specified by the vehicle
manufacturer.
5  Design and performance requirements of the fuel system
5.1  General
The fuel system consists of a high-pressure section, where the inner pressure is the same as in the fuel
container, and an intermediate- to low-pressure section, where the inner pressure is lower than that of
the high-pressure section.
The f
...