ISO 22734-2:2011

Hydrogen generators using water electrolysis process - Part 2: Residential applications

ISO 22734-2:2011 defines the construction, safety and performance requirements of packaged hydrogen gas generation appliances, herein referred to as hydrogen generators, using electrochemical reactions to electrolyse water to produce hydrogen. ISO 22734-2:2011 is applicable to hydrogen generators that use the following types of ion transport medium: a group of aqueous bases or solid polymeric materials with acidic function group additions, such as acid proton exchange membrane. ISO 22734-2:2011 is applicable to hydrogen generators intended for indoor and outdoor residential use in sheltered areas, such as car-ports, garages, utility rooms and similar areas of a residence. ISO 22734-2:2011 includes cord-connected equipment for outdoor and garage use only. Portable generators as well as hydrogen generators that can also be used to generate electricity, such as reversible fuel cells, are excluded from the scope of ISO 22734-2:2011. Hydrogen generators that also supply oxygen as a product are excluded from the scope of ISO 22734-2:2011.

Générateurs d'hydrogène utilisant le procédé d'électrolyse de l'eau — Partie 2: Applications résidentielles

General Information

• Status: Withdrawn
• Publication Date: 14-Nov-2011
• Withdrawal Date: 14-Nov-2011
• ICS: 71.100.20 - Gases for industrial application
• ICS: 71.120.99 - Other equipment for the chemical industry
• Technical Committee: ISO/TC 197 - Hydrogen technologies
• Drafting Committee: ISO/TC 197 - Hydrogen technologies
• Current Stage: 9599 - Withdrawal of International Standard
• Start Date: 30-Sep-2019
• Completion Date: 13-Dec-2025

Relations

• Revised: ISO 22734:2019 - Hydrogen generators using water electrolysis - Industrial, commercial, and residential applications
• Effective Date: 04-Nov-2015

Standards Content (Sample)

INTERNATIONAL  ISO
STANDARD 22734-2
First edition
2011-11-15
Hydrogen generators using water
electrolysis process —
Part 2:
Residential applications
Générateurs d’hydrogène utilisant le procédé d’électrolyse de l’eau —
Partie 2: Applications résidentielles
Reference number
ISO 22734-2:2011(E)
©
ISO 2011
©  ISO 2011
All rights reserved. Unless otherwise specified, 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 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 [e-mail]
Web www.iso.org
Published in Switzerland
ii © ISO 2011 – All rights reserved

Contents Page
Foreword . v
Introduction .vi
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 5
4 Operating conditions . 6
4.1 Energy consumption . 6
4.2 Feed water specifications . 6
4.3 Ambient environment . 7
4.4 Purge gas . 7
4.5 Oxygen venting . 7
4.6 Hydrogen venting . 7
4.7 Delivery of hydrogen . 8
5 Mechanical equipment . 8
5.1 General requirements . 8
5.2 General materials requirements . 9
5.3 Enclosures . 9
5.4 Pressure-bearing components . 11
5.5 Fans and ventilators .13
5.6 Pumps .13
5.7 Heat transfer system .13
5.8 Connection to potable water .14
6 Electrical equipment, wiring and ventilation .14
6.1 Fire and explosion hazard protection requirements .14
6.2 Electrical equipment .16
7 Control systems .18
7.1 General .18
7.2 Control function in the event of failure.19
7.3 Programmable electronic equipment .19
7.4 Start .19
7.5 Emergency stop .19
7.6 Stop .20
7.7 Self-correctable conditions .20
7.8 Interconnected installations .20
7.9 Safety components .20
7.10 Remote control systems .21
7.11 Alarms .21
7.12 Purge gas quantity .21
7.13 Reset .21
7.14 Suspension of safeguards .21
8 Ion transport medium .21
8.1 Electrolyte .21
8.2 Membrane .22
9 Protection of service personnel .22
10 Test methods .23
10.1 Type (qualification) tests .23
10.2 Routine tests .33
11 Marking and labelling .34
11.1 General requirements .34
11.2 Hydrogen generator marking .34
© ISO 2011 – All rights reserved  iii

11.3 Marking of components .35
11.4 Warning signs.35
12 Documentation accompanying the hydrogen generator .35
12.1 General .35
12.2 Hydrogen generator ratings .36
12.3 Hydrogen generator installation .36
12.4 Hydrogen generator operation .38
12.5 Hydrogen generator maintenance .39
Annex A (informative) Hydrogen-assisted corrosion .40
Annex B (informative) Flammability limits of hydrogen .41
Bibliography .42
iv © ISO 2011 – All rights reserved

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.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of technical committees is to prepare International Standards. Draft International Standards
adopted by the technical committees are circulated to the member bodies for voting. Publication as an
International Standard requires approval by at least 75 % of the member bodies casting a vote.
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.
ISO 22734-2 was prepared by Technical Committee ISO/TC 197, Hydrogen technologies.
ISO 22734 consists of the following parts, under the general title Hydrogen generators using water electrolysis
process:
—  Part 1: Industrial and commercial applications
—  Part 2: Residential applications
© ISO 2011 – All rights reserved  v

Introduction
The technology in this part of ISO 22734 is as follows.
In a hydrogen generator cell, electricity causes dissociation of water into hydrogen and oxygen molecules.
An electric current is passed between two electrodes separated by a conductive electrolyte or “ion transport
medium”, producing hydrogen at the negative electrode (cathode) and oxygen at the positive electrode (anode).
As water is HO, twice the volume of hydrogen is produced compared with oxygen.
Hydrogen gas produced using electrolysis technology can be utilized immediately or stored for later use.
The cell(s), and electrical, gas processing, ventilation, cooling, monitoring equipment and controls are
contained within an enclosure. Gas compression and feed water conditioning and auxiliary equipment may
also be included.
vi © ISO 2011 – All rights reserved

INTERNATIONAL STANDARD ISO 22734-2:2011(E)
Hydrogen generators using water electrolysis process —
Part 2:
Residential applications
1 Scope
This part of ISO 22734 defines the construction, safety and performance requirements of packaged hydrogen
gas generation appliances, herein referred to as hydrogen generators, using electrochemical reactions to
electrolyse water to produce hydrogen.
This part of ISO 22734 is applicable to hydrogen generators that use the following types of ion transport
medium:
—  group of aqueous bases;
—  solid polymeric materials with acidic function group additions, such as acid proton exchange membrane
(PEM).
This part of ISO 22734 is applicable to hydrogen generators intended for indoor and outdoor residential use
in sheltered areas, such as car-ports, garages, utility rooms and similar areas of a residence. This part of
ISO 22734 includes cord-connected equipment for outdoor and garage use only.
Portable generators as well as hydrogen generators that can also be used to generate electricity, such as
reversible fuel cells, are excluded from the scope of this part of ISO 22734.
Hydrogen generators that also supply oxygen as a product are excluded from the scope of this part of ISO 22734.
This part of ISO 22734 is intended to be used for certification purposes.
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.
ISO 1182, Reaction to fire tests for products — Non-combustibility test
ISO 3746, Acoustics — Determination of sound power levels and sound energy levels of noise sources using
sound pressure — Survey method using an enveloping measurement surface over a reflecting plane
ISO 3864-2, Graphical symbols — Safety colours and safety signs — Part 2: Design principles for product
safety labels
ISO 4126-1, Safety devices for protection against excessive pressure — Part 1: Safety valves
ISO 4126-2, Safety devices for protection against excessive pressure — Part 2: Bursting disc safety devices
ISO 4126-6, Safety devices for protection against excessive pressure — Part 6: Application, selection and
installation of bursting disc safety devices
ISO 7000, Graphical symbols for use on equipment — Index and synopsis
© ISO 2011 – All rights reserved  1

ISO 7010, Graphical symbols — Safety colours and safety signs — Registered safety signs
ISO 7866, Gas cylinders — Refillable seamless aluminium alloy gas cylinders — Design, construction and
testing
ISO 9300, Measurement of gas flow by means of critical flow Venturi nozzles
ISO 9951, Measurement of gas flow in closed conduits — Turbine meters
ISO 9614-1, Acoustics — Determination of sound power levels of noise sources using sound intensity — Part 1:
Measurement at discrete points
ISO 9809-1, Gas cylinders — Refillable seamless steel gas cylinders — Design, construction and testing —
Part 1: Quenched and tempered steel cylinders with tensile strength less than 1 100 MPa
ISO 10286, Gas cylinders — Terminology
ISO 10790, Measurement of fluid flow in closed conduits — Guidance to the selection, installation and use of
Coriolis meters (mass flow, density and volume flow measurements)
ISO 11119-1,  Gas cylinders of composite construction — Specification and test methods — Part 1: Hoop
wrapped composite gas cylinders and tubes
ISO 11119-2,  Gas cylinders of composite construction — Specification and test methods — Part 2: Fully
wrapped fibre reinforced composite gas cylinders with load-sharing metal liners
ISO 11119-3,  Gas cylinders of composite construction — Specification and test methods — Part 3: Fully
wrapped fibre reinforced composite gas cylinders and tubes with non-metallic and non-load-sharing metal
liners
ISO 12100, Safety of machinery — General principles for design — Risk assessment and risk reduction
ISO 12499, Industrial fans — Mechanical safety of fans — Guarding
ISO 13709, Centrifugal pumps for petroleum, petrochemical and natural gas industries
ISO 13850, Safety of machinery — Emergency stop — Principles for design
ISO 13854, Safety of machinery — Minimum gaps to avoid crushing of parts of the human body
ISO 13857, Safety of machinery — Safety distances to prevent hazard zones being reached by upper and lower
limbs
ISO 14511, Measurement of fluid flow in closed conduits — Thermal mass flowmeters
ISO 14687 (all parts), Hydrogen fuel — Product specification
ISO 14847, Rotary positive displacement pumps — Technical requirements
ISO 15534-1, Ergonomic design for the safety of machinery — Part 1: Principles for determining the dimensions
required for openings for whole-body access into machinery
ISO 15534-2, Ergonomic design for the safety of machinery — Part 2: Principles for determining the dimensions
required for access openings
ISO 15649, Petroleum and natural gas industries — Piping
ISO/TR 15916, Basic considerations for the safety of hydrogen systems
ISO 16111, Transportable gas storage devices — Hydrogen absorbed in reversible metal hydride
ISO 16528-1, Boilers and pressure vessels — Performance requirements
ISO 17398, Safety colours and safety signs — Classification, performance and durability of safety signs
2 © ISO 2011 – All rights reserved

ISO 22734-1,  Hydrogen generators using water electrolysis process — Part 1: Industrial and commercial
applications
ISO 26142, Hydrogen detection apparatus — Stationary applications
IEC 60034-1, Rotating electrical machines — Part 1: Rating and performance
IEC 60068-2-18:2010, Environmental Testing — Part 2-18: Tests — Test R and Guidance: Water
IEC 60079-0, Explosive atmospheres — Part 0: Equipment — General requirements
IEC 60079-2:2007, Explosive atmospheres — Part 2: Equipment protection by pressurized enclosures “p”
IEC 60079-10-1, Explosive atmospheres — Part 10-1: Classification of areas — Explosive gas atmospheres
IEC 60079-29-2,  Explosive atmospheres — Part 29-2: Gas detectors — Selection, installation, use and
maintenance of detectors for flammable gases and oxygen
IEC 60079-30-1,  Explosive atmospheres — Part 30-1: Electrical resistance trace heating — General and
testing requirements
IEC 60146 (all parts), Semiconductor converters
IEC 60204-1:2005, Safety of machinery — Electrical equipment of machines — Part 1: General requirements
IEC/TR 60269-5, Low-voltage fuses — Part 5: Guidance for the application of low-voltage fuses
IEC 60335-1:2010, Household and similar electrical appliances — Safety — Part 1: General requirements
IEC 60335-2-41, Household and similar electrical appliances — Safety — Part 2-41: Particular requirements
for pumps
IEC 60335-2-51, Household and similar electrical appliances — Safety — Part 2-51: Particular requirements
for stationary circulation pumps for heating and service water installations
IEC 60335-2-80, Household and similar electrical appliances — Safety — Part 2-80: Particular requirements
for fans
IEC 60364-4-43, Low-voltage electrical installations — Part 4-43: Protection for safety — Protection against
overcurrent
IEC 60364-6:2006, Low-voltage electrical installations — Part 6: Verification
IEC 60417, Graphical symbols for use on equipment
IEC 60439-1, Low-voltage switchgear and controlgear assemblies — Part 1: Type-tested and partially type-
tested assemblies
IEC 60439-2, Low-voltage switchgear and controlgear assemblies — Part 2: Particular requirements for busbar
trunking systems (busways)
IEC 60439-3, Low-voltage switchgear and controlgear assemblies — Part 3: Particular requirements for low-
voltage switchgear and controlgear assemblies intended to be installed in places where unskilled persons have
access for their use — Distribution boards
IEC 60439-5,  Low-voltage switchgear and controlgear assemblies — Part 5: Particular requirements for
assemblies for power distribution in public networks
IEC 60445, Basic and safety principles for man-machine interface, marking and identification — Identification
of equipment terminals, conductor terminations and conductors
IEC 60364-6:2006, Low-voltage electrical installations — Part 6: Verification
IEC 60529, Degrees of protection provided by enclosures (IP Codes)
© ISO 2011 – All rights reserved  3

IEC 60534 (all parts), Industrial-process control valves
IEC 60695-11-10, Fire hazard testing — Part 11-10: Test flames — 50 W horizontal and vertical flame test
methods
IEC 60695-11-20, Fire hazard testing — Part 11-20: Test flames — 500 W Flame test methods
IEC 60730-1:2010, Automatic electrical controls for household and similar use — Part 1: General requirements
IEC 60747 (all parts), Semiconductor devices — Discrete devices
IEC/TR 60877,  Procedures for ensuring the cleanliness of industrial-process measurement and control
equipment in oxygen service
IEC 60947-2, Low-voltage switchgear and controlgear — Part 2: Circuit-breakers
IEC 60947-3, Low-voltage switchgear and controlgear — Part 3: Switches, disconnectors, switch-disconnectors
and fuse-combination units
IEC 60947-4-1,  Low-voltage switchgear and controlgear — Part 4-1: Contactors and motor-starters —
Electromechanical contactors and motor-starters
IEC 60947-4-2, Low-voltage switchgear and controlgear — Part 4-2: Contactors and motor-starters — AC
semiconductor motor controllers and starters
IEC 60947-4-3, Low-voltage switchgear and controlgear — Part 4-3: Contactors and motor-starters — AC
semiconductor controllers and contactors for non-motor loads
IEC 60947-5-1,  Low-voltage switchgear and controlgear — Part 5-1: Control circuit devices and switching
elements — Electromechanical control circuit devices
IEC 60947-5-2, Low-voltage switchgear and controlgear — Part 5-2: Control circuit devices and switching
elements — Proximity switches
IEC 60947-5-3, Low-voltage switchgear and controlgear — Part 5-3: Control circuit devices and switching
elements — Requirements for proximity devices with defined behaviour under fault conditions
IEC 60947-5-5, Low-voltage switchgear and controlgear — Part 5-5: Control circuit devices and switching
elements — Electrical emergency stop device with mechanical latching function
IEC 60947-6-1, Low-voltage switchgear and controlgear — Part 6-1: Multiple function equipment — Transfer
switching equipment
IEC 60947-6-2, Low-voltage switchgear and controlgear — Part 6-2: Multiple function equipment — Control
and protective switching devices (or equipment)
IEC 60947-7-1, Low-voltage switchgear and controlgear — Part 7-1: Ancillary equipment — Terminal blocks for
copper conductors
IEC 60947-7-2, Low-voltage switchgear and controlgear — Part 7-2: Ancillary equipment — Protective conductor
terminal blocks for copper conductors
IEC 60950-1:2005, Information technology equipment — Safety — Part 1: General requirements
IEC 61000 (applicable parts), Electromagnetic compatibility (EMC)
IEC 61010-1:2010,  Safety requirements for electrical equipment for measurement, control, and laboratory
use — Part 1: General requirements
IEC 61069-7, Industrial-process measurement and control — Evaluation of system properties for the purpose
of system assessment — Part 7: Assessment of system safety
IEC 61131-1, Programmable controllers — Part 1: General information
4 © ISO 2011 – All rights reserved

IEC 61131-2, Programmable controllers — Part 2: Equipment requirements and tests
IEC 61204-1, Low-Voltage Power Supply Devices, D.C. Output — Part 1: Performance Characteristics
IEC 61508, Functional safety of electrical/electronic/programmable electronic safety-related systems
IEC 61511-1,  Functional safety: Safety instrumented systems for the process industry sector — Part 1:
Framework, definitions, system, hardware and software requirements
IEC 61558-1, Safety of power transformers, power supplies, reactors and similar products — Part 1: General
requirements and tests
IEC 61558-2-17,  Safety of power transformers, power supply units and similar ― Part 2-17: Particular
requirements for transformers for switch mode power supplies
IEC 61672-1, Electroacoustics — Sound level meters — Part 1: Specifications
IEC 61672-2, Electroacoustics — Sound level meters — Part 2: Pattern evaluation tests
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 22734-1 and the following apply.
3.1
accessible part
part or surface that can be touched by means of test probe B of IEC 61032, and if the part or surface is made
of metal, any conductive part connected to it
3.2
all-pole disconnection
disconnection of all supply conductors by a single initiating action
NOTE  For three-phase hydrogen generators, the neutral conductor is not considered to be a supply conductor.
3.3
built-in hydrogen generator
fixed hydrogen generator intended to be installed in a cabinet, in a prepared recess in a wall or in a similar
location
3.4
fixed hydrogen generator
hydrogen generator that is intended to be used while fastened to a support or while secured in a specific
location
NOTE  Adhesives are not recognized as a means for fastening a fixed hydrogen generator to a support.
3.5
hazard
potential source of harm
3.6
mechanical ventilation
replacement of air inside an enclosure with fresh air accomplished by a mechanical device (such as a fan) to
prevent or eliminate hazardous concentrations of hydrogen
3.7
natural ventilation
replacement of air inside an enclosure with fresh air accomplished exclusively by a natural draft caused, for
example, by the effects of wind, temperature gradients or buoyancy effects, to prevent or eliminate hazardous
concentrations of hydrogen
© ISO 2011 – All rights reserved  5

3.8
normal condition
condition in which all means for protection against hazards are intact
3.9
normal use
operation, including stand-by, according to the instructions for use or for the obvious intended purpose
NOTE  In most cases, normal use also implies normal condition, because the instructions for use will warn against
using the hydrogen generator when it is not in normal condition.
3.10
permanently connected
electrically connected to a supply by means of a permanent connection, which can be detached only by the
use of a tool
3.11
portable hydrogen generator
hydrogen generator that is intended to be moved while in operation or a hydrogen generator other than a fixed
hydrogen generator having a mass less than 18 kg
3.12
residential
relating to the use of hydrogen generators by laymen in private households (non-commercial and non-industrial
use)
3.13
single fault condition
condition in which one means for protection against hazard is defective or one fault is present which could
cause a hazard
NOTE  If a single fault condition results unavoidably in another single fault condition, the two failures are considered
as one single fault condition.
3.14
supply cord
flexible cord, for supply purposes, that is fixed to the hydrogen generator
3.15
tool
external device, including keys and coins, used to aid a person to perform a mechanical function
4 Operating conditions
4.1 Energy consumption
4.1.1 Electrical
The manufacturer shall specify, as outlined in IEC 60204-1, the electrical input rating for the hydrogen generator
in volts, amps or watts (W or VA) and hertz.
4.1.2 Other utilities
The manufacturer shall specify any other utilities required.
4.2 Feed water specifications
The manufacturer shall define the specifications for the feed water to be used in the hydrogen generator.
6 © ISO 2011 – All rights reserved

4.3 Ambient environment
The manufacturer shall specify the physical environment conditions for which the hydrogen generator is
designed. These shall include indoor or outdoor operation, the ambient temperature range, and the barometric
and humidity specifications.
4.4 Purge gas
Where the use of purge gas is required, the manufacturer shall specify the type of purge gas and its specifications.
4.5 Oxygen venting
4.5.1 General
The manufacturer shall specify if oxygen is to be vented indoors or outdoors. If oxygen is to be vented indoors,
the manufacturer shall specify if oxygen is to be vented directly out of the enclosure or within the enclosure.
4.5.2 Oxygen vented indoors
If oxygen is vented indoors, it shall not be vented directly through tubing from the enclosure in a way that could
allow the oxygen to be collected.
To preclude the formation of a hazardous enriched-oxygen atmosphere within the enclosure, oxygen purposely
vented inside the enclosure shall be diluted to a volume fraction of oxygen in air of less than 23,5 % before
being exhausted from the enclosure by a ventilation air stream. Classified electrical equipment that could come
in contact with enriched-oxygen mixtures shall be evaluated for suitability under the possible conditions (see
also 6.1.3 and 6.2.1).
The design of the ventilation shall dilute the oxygen concentration such that any gas flow exiting the enclosure
to the surrounding environment will not create a hazardous condition. Where mechanical ventilation is used to
dilute oxygen levels, means of detecting insufficient air ventilation shall be provided and cause the hydrogen
generator to shut down.
In addition, the room to which the hydrogen generator ventilates its air/gas mixture shall be sufficiently ventilated
to dilute the oxygen concentration in air below a volume fraction of 23,5 %. Room ventilation requirements shall
be provided in the installation instructions as required by 12.3.3 and a label warning about the presence of
oxygen and hydrogen shall be affixed as required by 11.4.
NOTE  Pressure-relief devices that vent indoors are to be considered when determining ventilation requirements.
4.5.3 Oxygen vented outdoors
If oxygen is vented outdoors, it shall be vented out of the enclosure to an outdoor location in a way that will
not create a hazardous condition. The installation instructions shall provide full details describing acceptable
methods as required by 12.3.3.
4.6 Hydrogen venting
4.6.1 General
Hydrogen shall be vented in a manner that will not create a hazardous condition in accordance with 4.6.2 and
4.6.3.
4.6.2 Hydrogen vented outdoors
Means shall be provided to connect a vent line to the hydrogen generator. Vent lines may be designed according
to ISO/TR 15916, or other similar standards.
© ISO 2011 – All rights reserved  7

4.6.3 Hydrogen vented indoors
Hydrogen gas may be vented indoors if it is diluted to a volume fraction of hydrogen in air of less than 1 %
before exiting the enclosure.
In addition, the room to which the generator ventilates its air/gas mixture shall be sufficiently ventilated to
preclude formation of a hydrogen-air mixture exceeding a volume fraction of 1 % except in dilution volume.
Room ventilation requirements shall be provided in the manual as required by 12.3.3 and a label warning about
the presence of hydrogen shall be affixed as required by 11.4.
4.7 Delivery of hydrogen
The manufacturer shall specify the hydrogen production rate, the hydrogen output pressure, temperature, and
the quality of the hydrogen produced by the hydrogen generator as in ISO 14687.
5 Mechanical equipment
5.1 General requirements
All hydrogen generator parts and all substances used in the hydrogen generator shall be
—  suitable for the range of temperatures and pressures to which the hydrogen generator is subjected during
expected usage,
—  resistant to the reactions, processes and other conditions to which the hydrogen generator is exposed
during expected usage,
—  suitable for their intended use, and
—  used within their rating and in accordance with the manufacturer’s instructions.
The hydrogen generator shall be designed to withstand expected shock and vibration loads, as well as the
specified ambient temperature range during transportation to the installation site and use. Means shall be
provided to facilitate safe handling of the hydrogen generator during lifting, moving and positioning operations.
The hydrogen generator shall be designed to remain stable when subjected to normal operational forces
imposed by users or by the environment during the installation or use.
The design of the hydrogen generator shall take into account the requirements specified in ISO 12100.
All parts of hydrogen generators, which are set or adjusted at the stage of manufacture and which should not
be manipulated by the user or the installer, shall be appropriately protected.
Manual controls shall be clearly marked and designed to prevent inadvertent adjustment or activation.
All parts shall be adequately protected from climatic and environmental conditions anticipated by the operating
conditions such as seismic-zone rating, snow, rain and wind loading.
All parts shall be of such construction as to be secure against displacement, distortion, warping or other
damage that could affect their functionality.
All parts that may be contacted during normal usage, adjustment or servicing shall be free from sharp projections
or edges.
All parts that require regular or routine maintenance or servicing, such as inspection, lubrication, cleaning,
replacement or similar function, shall be accessible and protected from unauthorized access with the use of a
special key or tool. All parts that are serviced by the residential user shall be accessible without exposing the
user to any hazards.
Moving parts and parts containing liquid shall be designed and mounted in such a way that in all foreseeable
modes of operation, the ejection of parts and liquid and the hazardous injection of liquid are prevented.
8 © ISO 2011 – All rights reserved

Where hazardous fluids are contained in the piping, precautions shall be taken in the design of the sampling
and take-off points to ensure safety in accordance with the manufacturer’s failure mode and effects analysis
(FMEA). Where hazardous fluids are contained in the piping, the sampling and take-off points shall be clearly
identified with cautionary symbols and protected from unauthorized access.
An FMEA pertaining to potential modes of failure and drift values for each safety-critical part shall be conducted
(see 6.2.4.1).
The hydrogen generator or parts of it where persons are intended to move about or stand shall be designed
and constructed to prevent persons slipping, tripping or falling on or off these parts.
5.2 General materials requirements
Materials employed in the hydrogen generator shall be suitable for their purpose.
All internal and external parts of the hydrogen generator that are directly exposed to moisture, ion transport
medium, process gas streams of hydrogen or oxygen, as well as parts used to seal or interconnect the same,
shall have the following material attributes during the manufacturer’s rated service life:
a)  retain mechanical stability with respect to strength (fatigue properties, endurance limit, creep strength)
when exposed to the full range of operating conditions specified in Clause 4;
b)  resist the chemical and physical action of the fluids that they contain and resist environmental degradation;
c)  be compatible with any other material used in conjunction so as to not have a synergistic and undesirable
effect.
When selecting materials and manufacturing methods, due consideration shall be given to the following:
—  hydrogen embrittlement and hydrogen-assisted corrosion, as indicated in Annex A and in ISO/TR 15916;
—  oxygen compatibility;
—  corrosion and wear resistance;
—  electrical conductivity;
—  electrical insulation;
—  impact strength;
—  aging resistance;
—  temperature effects;
—  galvanic corrosion;
—  erosion, abrasion, corrosion or other chemical attack;
—  resistance to ultraviolet (UV) radiation.
The auto-ignition temperature of any materials that may come into contact with oxygen during operation shall
have ignition temperatures in pure oyxgen atmosphere at the maximum operating pressure at least 50 °C
greater than the maximum temperature to which they are exposed during operation.
Process piping and vessels carrying oxygen shall be cleaned in accordance with IEC/TR 60877.
5.3 Enclosures
5.3.1 Minimum strength
The supporting structure and the enclosure shall have the strength, rigidity, durability, resistance to corrosion
and the other physical properties to support and protect all the components and piping, and withstand
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mechanical stress and shock expected during transport, installation and operation of the hydrogen generator.
Electrical enclosures shall meet the requirements of IEC 60204-1.
5.3.2 Environmental tolerance
The hydrogen generator enclosure shall be designed and tested for the intended installation environment as
classified in IEC 60529.
The enclosure of hydrogen generators intended for indoor use shall, as a minimum, meet the IP 34C rating
defined in IEC 60529.
The enclosure of hydrogen generators intended for outdoor use shall, as a minimum, meet the IP 54 rating
defined in IEC 60529.
NOTE  IEC 60068-2-68 provides recommended guidelines in test L for dust and sand.
5.3.3 Fire resistance
The hydrogen generator enclosure, together with the thermal insulating materials and their internal bonding
or adhesive attachment means, as well as the adjacent walls specified in 6.1.8, shall have a flammability
classification as follows:
a)  materials other than plastics shall have a flammability classification that will not support accelerating
combustion after electrical and fuel gas sources are removed when tested as in ISO 1182;
b)  plastic enclosures that cover sources of combustion or enclose live parts shall comply with the requirements
of 5V rated materials when tested in accordance with IEC 60695-11-20. Other plastic enclosures shall
comply with the requirements of HB and V rated materials when tested in accordance with IEC 60695-11-
10;
c)  composite materials shall meet the requirements of either a) or b) above.
5.3.4 Insulating materials
Thermal insulating materials on the enclosure of the hydrogen generator shall be mechanically or adhesively
retained in place and shall be protected against displacement or damage from anticipated loads and service
operation.
Thermal insulating materials and their internal bonding or adhesive attachment means shall withstand all air
velocities and temperatures to which they may be subjected in normal operation.
5.3.5 Access panels
Access panels shall be designed according to the requirements given in ISO 15534-1 and ISO 15534-2.
Access panels, covers or insulation that need to be removed for normal servicing and accessibility shall be
designed such that repeated removal and replacement will not cause damage or impair the insulating value.
Compliance shall be determined by the tests in 10.1.14.
An access panel, cover or door shall have a means for retaining it in place or opening it and shall require the
use of a tool, key or similar mechanical means to open. If located within classified areas, an access panel,
cover or door shall be designed to not generate sparking in accordance with IEC 60079-0 when being opened
or closed.
Removable access panels, covers and doors shall be designed so as to prevent them from being attached
in an improper position or being interchanged in a manner that may interfere with proper operation of the
hydrogen generator.
An enclosure large enough to admit service personnel to the enclosure shall have an access door that opens
outwards and, if equipped with a latch, it shall be equipped on the inside with fast-release hardware that can
be operated without a key or special tool.
10 © ISO 2011 – All rights reserved

5.3.6 Ventilation openings
Ventilation openings shall be designed so that they will not become obstructed during normal operation in
accordance with the expected application.
Where personnel can fully enter the enclosure, ventilation openings shall have a minimum total area of 0,003 m
per m of enclosure volume.
5.3.7 Containment of hazardous liquid leakage
Where a hydrogen generator contains hazardous liquids that can be harmful to personnel or the environment,
the hydrogen generator enclosure shall be designed to safely contain anticipated leaks as follows:
a)  the containment means shall have a capacity of 110 % of the maximum volume of the anticipated leak;
b)  a leak detector shall be fitted in the lowest area of the hydrogen generator enclosure where the leak would
be expected to accumulate. The detector signal shall cause the hydrogen generator to alarm and, where
possible, change the operating parameters to prevent further accumulation before 25 % of the maximum
volume of the anticipated leak accumulates.
5.3.8 Prevention of electrostatic accumulation
A terminal connected to earth shall be installed on the enclosure to prevent electrostatic accumulation.
5.4 Pressure-bearing components
5.4.1 General requirements
Special consideration shall be given to the following aspects of pressure-bearing components:
a)  support, constraint, anchoring, alignment and pre-tension techniques to mitigate excessive stresses and
strains being produced on flanges, connections, bellows or hoses;
b)  effects of sudden movement, high-pressure jets, water hammer, pressure-relieving-device actuations;
c)  means for drainage and cleaning of condensation during start-up and/or use occurring inside pressure-
bearing components for fluids which could cause damage from water hammer, vacuum collapse, corrosion
and uncontrolled chemical reactions;
d)  precautions in design and marking where explosive, flammable, or toxic fluids might be contained.
5.4.2 Built-in storage of hydrogen and other gases
If there is a need to store hydrogen or any pressurized gases other than oxygen, such as purge gas, calibration
gas, etc., inside the hydrogen generator, those gases shall be stored in any of the following types of containers
that are compatible with the particular gas being stored and the environmental conditions the hydrogen
generator is designed for:
a)  aluminium cylinders meeting the requirements of ISO 7866;
b)  steel cylinders meeting the requirements of ISO 9809-1;
c)  hoop wrapped composite cylinders meeting the requirements of ISO 11119-1;
d)  fully wrapped fibre reinforced composite gas cylinders with load-sharing metal liners meeting the
requirement
...