ISO 22734:2019
(Main)Hydrogen generators using water electrolysis — Industrial, commercial, and residential applications
Hydrogen generators using water electrolysis — Industrial, commercial, and residential applications
This document defines the construction, safety, and performance requirements of modular or factory-matched hydrogen gas generation appliances, herein referred to as hydrogen generators, using electrochemical reactions to electrolyse water to produce hydrogen. This document is applicable to hydrogen generators that use the following types of ion transport medium: — group of aqueous bases; — group of aqueous acids; — solid polymeric materials with acidic function group additions, such as acid proton exchange membrane (PEM); — solid polymeric materials with basic function group additions, such as anion exchange membrane (AEM). This document is applicable to hydrogen generators intended for industrial and commercial uses, and indoor and outdoor residential use in sheltered areas, such as car-ports, garages, utility rooms and similar areas of a residence. Hydrogen generators that can also be used to generate electricity, such as reversible fuel cells, are excluded from the scope of this document. Residential hydrogen generators that also supply oxygen as a product are excluded from the scope of this document.
Générateurs d'hydrogène utilisant le procédé de l'électrolyse de l'eau — Applications industrielles, commerciales et résidentielles
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Standards Content (Sample)
INTERNATIONAL ISO
STANDARD 22734
First edition
2019-09
Hydrogen generators using water
electrolysis — Industrial, commercial,
and residential applications
Générateurs d'hydrogène utilisant le procédé de l'électrolyse de
l'eau — Applications industrielles, commerciales et résidentielles
Reference number
©
ISO 2019
© ISO 2019
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
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Published in Switzerland
ii © ISO 2019 – All rights reserved
Contents Page
Foreword .v
Introduction .vi
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 4
4 Requirements . 7
4.1 Operating conditions . 7
4.1.1 Energy consumption . 7
4.1.2 Feed water specifications . 7
4.1.3 Ambient environment . 7
4.1.4 Purge gas . . . 7
4.1.5 Oxygen venting . 8
4.1.6 Hydrogen venting . 8
4.1.7 Delivery of hydrogen . 9
4.1.8 Delivery of oxygen . 9
4.2 Risk management . 9
4.3 Mechanical equipment . 9
4.3.1 General requirements . 9
4.3.2 General materials requirements .10
4.3.3 Enclosure requirements .11
4.3.4 Pressure-bearing components .13
4.3.5 Fans and ventilators .16
4.3.6 Pumps .16
4.3.7 Heat transfer system.17
4.3.8 Connection to potable water .17
4.3.9 Environmental tolerance .17
4.3.10 Equipment temperature limits and resistance to heat .17
4.3.11 Spillage, overflow, and drain .17
4.4 Electrical equipment, wiring and ventilation .18
4.4.1 Fire and explosion hazard protection requirements .18
4.4.2 Electrical equipment .20
4.5 Control systems .21
4.5.1 General.21
4.5.2 Safety control circuit .23
4.5.3 Control function in the event of failure .23
4.5.4 Programmable electronic equipment .23
4.5.5 Start .23
4.5.6 Emergency-stop .24
4.5.7 Stop .24
4.5.8 Self-correctable conditions .24
4.5.9 Interconnected installations .25
4.5.10 Safety components .25
4.5.11 Remote control systems .25
4.5.12 Alarms .25
4.5.13 Purge gas quantity .25
4.5.14 Reset .25
4.5.15 Suspension of safeguards .26
4.6 Ion transport medium .26
4.6.1 Electrolyte .26
4.6.2 Membrane .26
4.7 Protection of service personnel .27
5 Test methods .27
5.1 General .27
5.2 Type (qualification) tests .27
5.2.1 General requirements .27
5.2.2 Basic test arrangements .27
5.2.3 Reference test conditions .27
5.2.4 Electrical tests .29
5.2.5 Pressure test .31
5.2.6 Leakage test . .32
5.2.7 Dilution tests .33
5.2.8 Protection against the spread of fire tests .34
5.2.9 Temperature tests .34
5.2.10 Environmental test.34
5.2.11 Performance tests .35
5.2.12 Spillage, overflow, and drain test .35
5.2.13 Mechanical strength .35
5.2.14 Stability test .35
5.2.15 Vent tests .35
5.2.16 Sound level test .37
5.3 Routine tests .38
5.3.1 General requirements .38
5.3.2 Continuity of the protective bonding circuit test .38
5.3.3 Voltage test .38
5.3.4 Functional tests .38
5.3.5 Leakage test . .38
6 Marking and labelling .38
6.1 General requirements .38
6.2 Hydrogen generator marking .39
6.3 Marking of components .39
6.4 Warning signs .39
7 Documentation accompanying the hydrogen generator .40
7.1 General .40
7.2 Hydrogen generator ratings .40
7.3 Hydrogen generator installation .41
7.3.1 General.41
7.3.2 Specific requirements for permanently connected hydrogen generators .41
7.3.3 Specific requirements for indoor installations .41
7.3.4 Specific requirements for built-in hydrogen generator appliances .42
7.3.5 Lifting . .42
7.4 Hydrogen generator operation .42
7.5 Hydrogen generator maintenance .43
Annex A (informative) Hydrogen-assisted corrosion .44
Annex B (informative) Flammability limits of hydrogen .45
Bibliography .46
iv © ISO 2019 – 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.
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 (see 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 (see 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.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and
expressions related to conformity assessment, as well as information about ISO's adherence to the
World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT) see www .iso
.org/iso/foreword .html.
This document was prepared by Technical Committee ISO/TC 197, Hydrogen technologies.
This first edition cancels and replaces ISO 22734-1:2008 and ISO 22734-2:2011, which have been
combined and technically revised. The technical revisions add Alkaline Exchange Membranes to the
document scope, update Normative references, clarify pressure terminology definitions, and simplify
Risk Management requirements. This document is reorganized into 7 clauses, where all design
requirements are now found in Clause 4, and all test methods are now found in Clause 5.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www .iso .org/members .html.
Introduction
In a hydrogen generator electrochemical 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 H O, 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, feed water conditioning, and auxiliary equipment may
also be included.
This document is intended to be used for certification purposes.
vi © ISO 2019 – All rights reserved
INTERNATIONAL STANDARD ISO 22734:2019(E)
Hydrogen generators using water electrolysis — Industrial,
commercial, and residential applications
1 Scope
This document defines the construction, safety, and performance requirements of modular or factory-
matched hydrogen gas generation appliances, herein referred to as hydrogen generators, using
electrochemical reactions to electrolyse water to produce hydrogen.
This document is applicable to hydrogen generators that use the following types of ion transport medium:
— group of aqueous bases;
— group of aqueous acids;
— solid polymeric materials with acidic function group additions, such as acid proton exchange
membrane (PEM);
— solid polymeric materials with basic function group additions, such as anion exchange membrane
(AEM).
This document is applicable to hydrogen generators intended for industrial and commercial uses, and
indoor and outdoor residential use in sheltered areas, such as car-ports, garages, utility rooms and
similar areas of a residence.
Hydrogen generators that can also be used to generate electricity, such as reversible fuel cells, are
excluded from the scope of this document.
Residential hydrogen generators that also supply oxygen as a product are excluded from the scope of
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.
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 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 flowmeters (mass flow, density and volume flow measurements)
ISO 11119-1, Gas cylinders — Refillable composite gas cylinders and tubes — Design, construction and
testing — Part 1: Hoop wrapped fibre reinforced composite gas cylinders and tubes up to 450 l
ISO 11119-2, Gas cylinders — Refillable composite gas cylinders and tubes — Design, construction and
testing — Part 2: Fully wrapped fibre reinforced composite gas cylinders and tubes up to 450 l with load-
sharing metal liners
ISO 11119-3, Gas cylinders — Refillable composite gas cylinders and tubes — Design, construction and
testing — Part 3: Fully wrapped fibre reinforced composite gas cylinders and tubes up to 450L with non-
load-sharing metallic or non-metallic 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 function — 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 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 16111, Transportable gas storage devices — Hydrogen absorbed in reversible metal hydride
ISO 16528-1, Boilers and pressure vessels — Part 1: Performance requirements
ISO 17398, Safety colours and safety signs — Classification, performance and durability of safety signs
ISO 26142, Hydrogen detection apparatus — Stationary applications
IEC 31010:2019, Risk management — Risk assessment techniques
IEC 60068-2-18:2017, Environmental testing — Part 2-18: Tests — Test R and guidance: Water
IEC 60079 (all parts), Explosive atmospheres
2 © ISO 2019 – All rights reserved
IEC 60204-1:2016, Safety of machinery — Electrical equipment of machines — Part 1: General requirements
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 60364-4-41, 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 60445, Basic and safety principles for man-machine interface, marking and identification —
Identification of equipment terminals, conductor terminations and conductors
IEC 60529, Degrees of protection provided by enclosures (IP Codes)
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 60730-1:2013, Automatic electrical controls for household and similar use — Part 1: General
requirements
IEC 60947-1, Low-voltage switchgear and controlgear — Part 1: General rules
IEC 60950-1:2005, Information technology equipment — Safety — Part 1: General requirements
IEC 60998-2-2, Connecting devices for low-voltage circuits for household and similar purposes — Part 2-2:
Particular requirements for connecting devices as separate entities with screwless-type clamping units
IEC 60999-1, Connecting devices — Electrical copper conductors — Safety requirements for screw-type and
screwless-type clamping units — Part 1: General requirements and particular requirements for clamping
units for conductors from 0,2 mm2 up to 35 mm2 (included)
IEC 60999-2, Connecting devices — Electrical copper conductors — Safety requirements for screw-type
and screwless-type clamping units — Part 2: Particular requirements for clamping units for conductors
above 35 mm2 up to 300 mm2 (included)
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
IEC 61131-2, Programmable controllers — Part 2: Equipment requirements and tests
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 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 following terms and definitions apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https: //www .iso .org/obp
— IEC Electropedia: available at http: //www .electropedia .org/
3.1
area classification
classification of hazardous areas (3.2) according to the probability of the existence of an explosive
atmosphere, in order to relate the selection of electrical apparatus for use in the area to the degree of
hazard (3.12)
3.2
hazardous area
area in which an explosive atmosphere is present, or may be expected to be present, in quantities such
as to require special precautions for the construction, installation and use of electrical apparatus
3.3
built-in hydrogen generator appliance
hydrogen generator intended to be installed in a cabinet, in a prepared recess in a wall, or in a similar
location
3.4
commercial use
use of hydrogen generators by laymen in non-manufacturing business facilities such as stores, hotels,
office buildings, educational institutes, filling stations, warehouses, and other non-residential locations
3.5
containment system
part of the apparatus containing a flammable substance that may constitute a source of release
3.6
dilution
continuous supply of a purge gas (3.27) at such a rate that the concentration of a flammable substance
inside an enclosure (3.9) is maintained at a value outside the explosive (flammable) limits at any
potential ignition source (that is to say, outside the dilution area)
3.7
dilution volume
location in the vicinity of a source of release where the concentration of flammable substance is not
diluted to a level below the lower flammability limit (LFL)
Note 1 to entry: Dilution (3.6) of oxygen by inert gas can result in a concentration of flammable gas or vapour
above the upper flammability limit (UFL).
Note 2 to entry: Annex B provides information on the flammability limits of hydrogen.
3.8
electrochemical cell
assembly of electrodes, fluid containment, flow means, and electrical current conduction means that
may include product gas separation membranes (3.19) and may be arranged as single unipolar cells
or in bipolar cell stacks within or without a process containment vessel, for the purpose of producing
hydrogen and/or oxygen from water
4 © ISO 2019 – All rights reserved
3.9
enclosure
containment and support structure(s) protecting a hydrogen generator from specific environmental and
climatic conditions and protecting persons and livestock from incidental contact with the hazardous
parts of the hydrogen generator
3.10
enriched oxygen atmosphere
gas that contains a volume fraction of more than 23,5 % oxygen with the remainder of its components
being inert
3.11
factory-matched
engineered in a factory to correspond with each other and work together, separately packed for storage
and transportation, and intended to be assembled together at the point of utilization
[SOURCE: ISO 16110-1:2007, 3.21, modified — The term has been changed from "factory matched unit"
to "factory-matched"; the words "system components" have been removed.]
3.12
hazard
potential source of harm
3.13
hazardous condition
condition that may adversely affect the safety of the hydrogen generator operation
Note 1 to entry: Examples of hazardous conditions include having an enriched oxygen atmosphere (3.10), a
hydrogen concentration exceeding the lower flammability limit, an ignition source in a classified area, an
overpressure, or an over temperature.
3.14
industrial use
use of hydrogen generators by qualified and experienced personnel in a controlled manufacturing or
processing environment
3.15
ion transport medium
medium that provides ionic transport within the cell
3.16
maximum allowable working pressure
MAWP
maximum pressure permissible in a vessel or system at the temperature specified for the pressure
Note 1 to entry: The maximum allowable working pressure can also be defined as the design pressure, the
maximum allowable operating pressure, the maximum permissible working pressure, or the maximum allowable
pressure for the rating of pressure vessels and equipment manufactured in accordance with national pressure
vessel codes.
3.17
maximum operating pressure
MOP
maximum pressure that can be expected by the pressure containing components when the hydrogen
generator is functioning within its design and control parameters, including anticipated transients
3.18
mechanical ventilation
replacement of air inside an enclosure (3.9) with fresh air accomplished by a mechanical device (such as
a fan) to prevent or eliminate hazardous concentrations of hydrogen
3.19
membrane
material that provides separation between oxygen and hydrogen product gases while allowing ionic
transport within the cell
3.20
natural ventilation
replacement of air inside an enclosure (3.9) 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
3.21
normal condition
condition in which all means for protection against hazards (3.12) are intact
3.22
normal use
operation, including stand-by, according to the instructions for use or for the obvious intended purpose
Note 1 to entry: In most cases, normal use also implies normal condition (3.21), because the instructions for use
will warn against using the hydrogen generator when it is not in normal condition.
3.23
pressure relief device
PRD
device designed to release pressure in order to prevent a rise in pressure above a specified value due to
emergency or abnormal conditions
Note 1 to entry: PRDs are activated by pressure or another parameter, such as temperature, and are either re-
closing devices (such as valves) or non-re-closing devices (such as rupture disks and fusible plugs). Common
designations for these specific types of PRDs are as follows:
— Pressure safety valve (PSV) — pressure activated valve that opens at a specified set point to protect a system
from rupture and re-closes when the pressure falls below the set point.
— Temperature-activated pressure relief device (TPRD) — PRD that opens at a specified temperature to protect
a system from rupture and remains open.
3.24
pressure-bearing component
part subject to a positive internal pressure of 100 kPa or greater
3.25
permanently connected
electrically connected to a supply by means of a permanent connection, which can be detached only by
the use of a tool (3.34)
3.26
portable hydrogen generator
hydrogen generator that is not intended to be permanently fastened in a specific location and can be
carried easily by a person
3.27
purge gas
gas used to maintain protective pressurization or to dilute flammable gas or vapour to a concentration
well below the lower flammability limit
3.28
purging
passage of sufficient volume of a purge gas (3.27) through a pressurized enclosure (3.9) and its ducts,
before the application of voltage to the apparatus, to reduce any ignitable (flammable) gas atmosphere
to a concentration well below the lower flammability limit
6 © ISO 2019 – All rights reserved
3.29
residential use
use of hydrogen generators by laymen in private households (non-commercial and non-industrial use)
3.30
risk assessment
overall process of risk identification, risk analysis, risk evaluation, and risk mitigation
3.31
single fault condition
condition in which one means for protection against hazards (3.12) is defective or one fault is present
which could cause a hazard
Note 1 to entry: If a single fault condition results unavoidably in another single fault condition, the two failures
are considered as one single fault condition.
3.32
standard conditions
conditions to which the volume or other properties of a gas are referred, and which are represented by
a temperature of 273,15 K (0 °C) and an absolute pressure of 100 kPa
3.33
supply cord
flexible cord, for supply purposes, that is fixed to the hydrogen generator
3.34
tool
external device, including keys and coins, used to aid a person to perform a mechanical function
4 Requirements
4.1 Operating conditions
4.1.1 Energy consumption
4.1.1.1 Electrical
The manufacturer shall specify, as outlined in IEC 60204-1, the electrical input rating for the hydrogen
generator in volt-amperes (VA) or watts (W) and hertz.
4.1.1.2 Other utilities
The manufacturer shall specify any other utilities required.
4.1.2 Feed water specifications
The manufacturer shall define the specifications for the feed water to be used in the hydrogen generator.
4.1.3 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.
4.1.4 Purge gas
Where the use of purge gas is required, the manufacturer shall specify the type of purge gas and its
specifications.
4.1.5 Oxygen venting
4.1.5.1 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. Oxygen vents shall meet the IP rating of 4.3.9.
4.1.5.2 Oxygen vented outdoors
If oxygen is vented outdoors, it shall be vented out of any 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 7.3.1.
4.1.5.3 Oxygen vented within enclosures or indoors
To preclude the formation of a hazardous enriched-oxygen atmosphere within an enclosure, oxygen
purposely vented inside the enclosure shall be diluted by a ventilation air stream to a volume fraction
of oxygen in air of less than 23,5 % before being exhausted from the enclosure. For electrical equipment
that could come in contact with enriched-oxygen mixtures, see 4.4.1.5.
For systems venting oxygen into either the enclosure or indoors, room ventilation guidance to
preclude a room oxygen concentration in air above a volume fraction of 23,5 % shall be provided in the
installation instructions as required by 7.3.3. A label warning about the presence of oxygen shall be
affixed as required by 6.4.
The design of the enclosure 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 residential applications, oxygen shall not be vented indoors directly through tubing or piping in a
way that facilitates oxygen product collection (see 4.1.8). The manufacturer shall provide instruction
and warnings to exclude oxygen collection per 7.3.1.
Pressure relief devices that vent within enclosures or indoors shall be considered when determining
dilution and ventilation requirements.
4.1.6 Hydrogen venting
4.1.6.1 General
Hydrogen shall be vented in a manner that will not create a hazardous condition in accordance with
4.1.6.2 and 4.1.6.3. Hydrogen vents shall meet the IP rating of 4.3.9.
4.1.6.2 Hydrogen vented outdoors
Means shall be provided to connect a hydrogen vent line to the hydrogen generator. When supplied
with the hydrogen generator, vent lines should be designed according to ISO/TR 15916, or other similar
standards.
NOTE Additional guidance on hydrogen vents can be found in CGA G-5.5 and EIGA Doc 211/17.
4.1.6.3 Hydrogen vented within enclosures or indoors
Hydrogen gas may be vented within enclosures if it is diluted to a volume fraction of hydrogen in air of
less than 1 % before exiting the enclosure.
8 © ISO 2019 – All rights reserved
Room ventilation guidance to preclude a room hydrogen concentration in air above a volume fraction of
1 % shall be provided in the installation instructions as required by 7.3.3 and a label warning about the
presence of hydrogen shall be affixed as required by 6.4.
4.1.7 Delivery of hydrogen
The manufacturer shall specify the hydrogen production rate, the hydrogen output pressure range,
hydrogen temperature range, and the hydrogen quality under standard conditions.
NOTE ISO 14687 includes specifications for hydrogen quality for use in representative applications.
4.1.8 Delivery of oxygen
Industrial and commercial equipment may deliver oxygen. Where applicable, the manufacturer shall
specify the oxygen production rate, the oxygen output pressure range, hydrogen temperature range,
and the quality of the oxygen produced by the hydrogen generator at standard conditions.
Residential hydrogen generators shall not deliver oxygen.
4.2 Risk management
The manufacturer shall perform a risk assessment on the hydrogen generator design using one or more
stru
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