SIST-TS CEN ISO/TS 15916:2026

SLOVENSKI STANDARD
01-julij-2026
Tehnologija vodika - Osnovni vidiki varnosti sistemov vodika (ISO/TS 15916:2026)
Hydrogen technologies - Basic considerations for the safety of hydrogen systems
(ISO/TS 15916:2026)
Wasserstofftechnologien - Grundsätzliche Betrachtungen zur Sicherheit von
Wasserstoffsystemen (ISO/TS 15916:2026)
Technologies de l'hydrogène - Considérations fondamentales pour la sécurité des
systèmes à l'hydrogène (ISO/TS 15916:2026)
Ta slovenski standard je istoveten z: CEN ISO/TS 15916:2026
ICS:
27.075 Tehnologija vodika Hydrogen technologies
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

TECHNICAL SPECIFICATION CEN ISO/TS 15916

SPÉCIFICATION TECHNIQUE
TECHNISCHE SPEZIFIKATION
February 2026
ICS 27.075
English version
Hydrogen technologies - Basic considerations for the
safety of hydrogen systems (ISO/TS 15916:2026)
Technologies de l'hydrogène - Considérations Wasserstofftechnologien - Grundsätzliche
fondamentales pour la sécurité des systèmes à Betrachtungen zur Sicherheit von
l'hydrogène (ISO/TS 15916:2026) Wasserstoffsystemen (ISO/TS 15916:2026)
This Technical Specification (CEN/TS) was approved by CEN on 12 January 2026 for provisional application.

The period of validity of this CEN/TS is limited initially to three years. After two years the members of CEN and CENELEC will be
requested to submit their comments, particularly on the question whether the CEN/TS can be converted into a European
Standard.
CEN and CENELEC members are required to announce the existence of this CEN/TS in the same way as for an EN and to make the
CEN/TS available promptly at national level in an appropriate form. It is permissible to keep conflicting national standards in
force (in parallel to the CEN/TS) until the final decision about the possible conversion of the CEN/TS into an EN is reached.

CEN and CENELEC members are the national standards bodies and national electrotechnical committees of Austria, Belgium,
Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy,
Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Republic of North Macedonia, Romania, Serbia,
Slovakia, Slovenia, Spain, Sweden, Switzerland, Türkiye and United Kingdom.

CEN-CENELEC Management Centre:
Rue de la Science 23, B-1040 Brussels
© 2026 CEN/CENELEC All rights of exploitation in any form and by any means
Ref. No. CEN ISO/TS 15916:2026 E
reserved worldwide for CEN national Members and for
CENELEC Members.
Contents Page
European foreword . 3

European foreword
This document (CEN ISO/TS 15916:2026) has been prepared by Technical Committee ISO/TC 197
"Hydrogen technologies" in collaboration with Technical Committee CEN-CENELEC/ JTC 6 “Hydrogen in
energy systems” the secretariat of which is held by NEN.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CEN-CENELEC shall not be held responsible for identifying any or all such patent rights.
Any feedback and questions on this document should be directed to the users’ national standards
body/national committee. A complete listing of these bodies can be found on the CEN and CENELEC
websites.
According to the CEN-CENELEC Internal Regulations, the national standards organizations of the
following countries are bound to announce this Technical Specification: Austria, Belgium, Bulgaria,
Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland,
Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Republic of
North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Türkiye and the
United Kingdom.
Endorsement notice
The text of ISO/TS 15916:2026 has been approved by CEN-CENELEC as CEN ISO/TS 15916:2026
without any modification.
Technical
Specification
ISO/TS 15916
First edition
Hydrogen technologies — Basic
2026-01
considerations for the safety of
hydrogen systems
Technologies de l'hydrogène — Considérations fondamentales
pour la sécurité des systèmes à l'hydrogène
Reference number
ISO/TS 15916:2026(en) © ISO 2026

ISO/TS 15916:2026(en)
© ISO 2026
All rights reserved. Unless otherwise specified, or required in the context of its implementation, 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
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CH-1214 Vernier, Geneva
Phone: +41 22 749 01 11
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii
ISO/TS 15916:2026(en)
Contents Page
Foreword .vi
Introduction .vii
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Overview of hydrogen applications .12
4.1 Basic hydrogen infrastructure . 12
4.1.1 Categories of infrastructure . 12
4.1.2 Production . 13
4.1.3 Storage and transport. 13
4.1.4 Hydrogen end use applications .14
4.2 Typical hydrogen system components . 15
4.2.1 General . 15
4.2.2 Storage vessels . 15
4.2.3 Fluid delivery lines, piping, joints, and seals . 15
4.2.4 Flow controls . 15
4.2.5 Pressure-relief systems . 15
4.2.6 Detection methods .16
4.2.7 Other components .16
4.2.8 Considerations for conditions external to the system .16
4.3 Hydrogen fuel .16
4.4 Environmental effects .17
5 Basic properties of hydrogen . 17
5.1 General properties .17
5.1.1 Atomic and molecular properties .17
5.1.2 Appearance and general characteristics .17
5.2 Selected thermophysical properties .18
5.2.1 General .18
5.2.2 Selected thermophysical properties of gaseous hydrogen .18
5.2.3 Selected thermophysical properties of cryogenic liquid hydrogen .18
5.3 Basic combustion properties .19
5.3.1 General remark on safety characteristics .19
5.3.2 Selected combustion properties of hydrogen .19
5.3.3 Deflagration . 20
5.3.4 Detonation .21
5.3.5 Explosions .21
5.3.6 Flammability limits .21
5.3.7 Ignition energy and minimum ignition energy as applied to deflagration . 22
6 Safety considerations for the use of gaseous and liquid hydrogen .23
6.1 General . 23
6.2 Hazards involved as a consequence of the properties of hydrogen .24
6.2.1 General .24
6.2.2 Gaseous hydrogen .24
6.2.3 Liquid hydrogen .24
6.3 Factors involved in combustion hazards . 25
6.3.1 Aspects of combustion . 25
6.3.2 Non-premixed combustion processes . 25
6.3.3 Explosions . 26
6.4 Factors involved in pressure hazards .27
6.4.1 General .27
6.4.2 Gaseous storage .27
6.4.3 Liquid hydrogen .27
6.5 Factors involved in low temperature hazards .27

iii
ISO/TS 15916:2026(en)
6.6 Factors involved in hydrogen embrittlement hazards . 28
6.6.1 Hydrogen embrittlement . 28
6.6.2 Hydrogen attack . . 28
6.7 Health hazards. 28
6.7.1 Cold burns . 28
6.7.2 High temperature burns . 28
6.7.3 Asphyxiation . 28
6.7.4 Combustion by-products . 29
7 Mitigation and control of hazards and risks .29
7.1 General mitigation and control of hazards and risk . 29
7.1.1 General . 29
7.1.2 Lessons learned from past experience . 29
7.1.3 Addressing hazards . 30
7.1.4 Minimizing the severity of the consequences of hazards . 30
7.2 Mitigation of design hazards and risks.31
7.2.1 Inherently safer design .31
7.2.2 Considerations in the selection of suitable construction material .31
7.2.3 Considerations for vessels and components . 33
7.2.4 Prevention of overpressure . 33
7.2.5 Considerations for piping, joints, and connections. 33
7.2.6 Cleaning considerations . 34
7.2.7 Component considerations . 35
7.3 Prevention and mitigation of fire and explosion hazards and risks . 36
7.3.1 General . 36
7.3.2 Prevention of unwanted hydrogen/oxidizer mixtures . 36
7.3.3 Identification of hazardous areas . 36
7.3.4 Ignition .37
7.3.5 Deflagration and detonation. 38
7.3.6 Oxygen enrichment . 38
7.4 Detection considerations . 39
7.4.1 Hydrogen release detection. 39
7.4.2 Fire detection . 40
7.5 Considerations for facilities . 40
7.5.1 General . 40
7.5.2 Locations . 40
7.5.3 Exclusion areas .41
7.5.4 Protecting barricades .41
7.5.5 Safety control equipment .41
7.5.6 Disposal of hydrogen .42
7.5.7 Ground material .43
7.5.8 Buildings .43
7.5.9 Ventilation .43
7.5.10 Electrical components . 44
7.5.11 Alarms and warning devices .45
7.5.12 Fire protection and fire fighting .45
7.6 Considerations for operations . 46
7.6.1 General . 46
7.6.2 Operating procedures . 46
7.6.3 Personal protective equipment . 46
7.6.4 Cool-down .47
7.6.5 Transportation .47
7.6.6 Storage and transfer operations.47
7.6.7 Safety procedures . 48
7.7 Recommended practices for organizations . 49
7.7.1 General . 49
7.7.2 Control through organizational policies and procedures . 50
7.7.3 Use of approved procedures and checklists. 50
7.7.4 Conduct appropriate reviews. 50

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ISO/TS 15916:2026(en)
7.7.5 Approved maintenance and quality control programmes . 50
7.7.6 Personnel education/training . 50
7.7.7 Hazard and operability assessment .51
Annex A (informative) Hydrogen properties .52
Annex B (informative) Hydrogen combustion data .56
Annex C (informative) Material data.59
Annex D (informative) Other storage options .64
Bibliography .65

v
ISO/TS 15916:2026(en)
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 document 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).
ISO draws attention to the possibility that the implementation of this document may involve the use of (a)
patent(s). ISO takes no position concerning the evidence, validity or applicability of any claimed patent
rights in respect thereof. As of the date of publication of this document, ISO had not received notice of (a)
patent(s) which may be required to implement this document. However, implementers are cautioned that
this may not represent the latest information, which may be obtained from the patent database available at
www.iso.org/patents. ISO shall not be held responsible for identifying any or all such patent rights.
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, in collaboration
with the European Committee for Standardization (CEN) Technical Committee CEN/CLC/JTC 6, Hydrogen in
energy systems, in accordance with the Agreement on technical cooperation between ISO and CEN (Vienna
Agreement).
This first edition of ISO/TS 15916 cancels and replaces ISO/TR 15916:2015, which has been technically
revised.
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.

vi
ISO/TS 15916:2026(en)
Introduction
The focus of this document is on relatively new hydrogen energy applications. The intent is to provide, those
unfamiliar with the technology, a basis upon which to understand the safety issues. This document concerns
itself with applications that derive their utility from the chemical reactions of hydrogen and does not apply
to applications based on nuclear processes.
Traditionally, hydrogen has been used extensively in the petrochemical and chemical industries and in
smaller quantities in the electronics, steel-producing, glass-making, and food hydrogenation industries.
Given the promise that hydrogen brings as an efficient energy carrier and a fuel with minimal environmental
impact, systems are being developed that produce hydrogen using variety of energy sources and feedstocks
such as sunlight, wind, biomass, hydropower and fossil fuels, for use in energy applications for home and
office heating, generation of electricity and transportation.
The safe use of hydrogen as a fuel is a primary goal to facilitate the rapid emergence of these hydrogen
technologies. A key element in the safe use of hydrogen is to understand its unique safety-related properties
and related phenomena, and that there are acceptable engineering approaches to controlling the hazards
and risks associated with the use of hydrogen. This document describes the hazards associated with the use
and presence of hydrogen, discusses the properties of hydrogen relevant to safety, and provides a general
discussion of approaches taken to mitigate hydrogen hazards. The aim of this document is to promote the
acceptance of hydrogen technologies by providing key information to regulators and by educating people
involved with hydrogen safety issues.
The development of International Standards to eliminate barriers to international trade and to simplify the
arduous regulatory process by providing hydrogen-specific standards to allow implementation for rapidly
emerging technologies was among the needs identified by the ISO/TC 197. This document is one of many that
have been developed, or are in the process of being developed. Detailed safety requirements associated with
specific hydrogen applications are treated in separate International Standards. This document provides
an informative reference for those separate standards as a common, consistent source of safety-related
hydrogen information. This is expected to result in a reduction in duplication and possible inconsistencies in
these separate standards.
The considerations presented in this document are broad, general, and attempt to address most aspects of
hydrogen safety. The degree to which these guidelines are applied will vary according to the specifics of the
application (such as the conditions and quantity of hydrogen involved, and the way in which the hydrogen
is used). Industrial users may find large portions of the guidelines, presented herein, applicable for their
operations. It is not expected that the general public will be required to apply this degree of knowledge to
safely operate a hydrogen appliance. It is anticipated that good appliance design, coupled with appropriate
care in installation, will reduce the degree of safety considerations to levels that are deemed acceptable by
the public for common appliances. The manufacturers of hydrogen appliances will need to consider these
guidelines to tailor sufficient specific information for the operation of their appliances, in the environment
in which they are to be used, and for the audience that will use them. Readers are encouraged to keep these
points in mind as they consider the information presented in this document. Hydrogen has been safely used
in many different applications over many years. Adherence to the principles presented in this document can
lead to a continuation of the safe and sustainable use of hydrogen.

vii
Technical Specification ISO/TS 15916:2026(en)
Hydrogen technologies — Basic considerations for the safety
of hydrogen systems
1 Scope
This document provides guidelines for the use of hydrogen in its gaseous and liquid forms as well as its storage
in either of these or other forms (hydrides). This document identifies the basic safety concerns, hazards and
risks, and describes the properties of hydrogen that are relevant to safety. Detailed safety requirements
associated with specific hydrogen applications are treated in separate International Standards.
“Hydrogen” in this document means protium (the most common isotope of hydrogen) ( H), not deuterium
2 3
( H) or tritium ( H).
2 Normative references
There are no normative references in this document.
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https://www.iso.org/obp
— IEC Electropedia: available at https://www.electropedia.org/
3.1
ambient conditions
local surrounding conditions characterized by the temperature and pressure at a particular location, such
as a city or facility
Note 1 to entry: See normal temperature and pressure (3.69).
3.2
annealing
heat treatment process used to soften hard steel so that it can be machined or cold-worked
3.3
arrested flame
combustion process that is stopped or flame that is put out
3.4
auto-ignition
ignition that does not require external ignition energy because the thermal energy of the molecules alone is
enough to overcome the activation threshold for combustion initiation
3.5
auto-ignition temperature
lowest temperature at which auto-ignition (3.4) occurs
3.6
backfill
process by which a desired gas is used to replace an undesired gas in a system volume

ISO/TS 15916:2026(en)
Note 1 to entry: Typically, the undesired gas is first removed by evacuation with a vacuum pump, then the desired gas
is put in.
3.7
blast wave
intense pressure wave set in motion by the shock waves (3.91) and/or hot product gases of a fast deflagration
(3.20) or detonation (3.23) that impinges upon the surroundings, typically air
3.8
boiling liquid expanding vapour explosion
BLEVE
phenomenon that occurs when a vessel containing a pressurized liquid substantially above its (atmospheric)
boiling point is ruptured, releasing the content explosively
3.9
Bourdon tube
thin-wall curved tube that is closed at one end and attached to a pressure source at the other end
Note 1 to entry: Pressure changes cause a change in the curvature of the Bourdon tube that is used to indicate the
pressure in the system.
3.10
buoyancy
vertical force exerted on a body of less dense gas by the surrounding heavier static gas, typically air
3.11
catalytic converter
catalyst that is used for converting ortho-hydrogen to para-hydrogen in a liquefaction process so that the
liquid hydrogen produced is mostly para-hydrogen
Note 1 to entry: Some commonly used catalysts in this conversion process are hydrous ferric oxide, chromic oxide on
alumina particles, and nickel-based compounds.
3.12
check valve
valve that operates on differential pressure and allows flow in one direction only
3.13
combustion
reaction process by which a flammable substance is oxidized, producing hot product gases, heat, radiation,
and possibly pressure waves
Note 1 to entry: An explosion (3.36) in the sense of this document is a combustion process.
3.14
component
any part of a complete item or system
3.15
confined space
area with limited access, as described in national regulations, which requires special considerations for
entry
[SOURCE: ISO 16972:2020, 3.58]
3.16
confinement
physical restriction, sufficient to influence the combustion process or to facilitate the accumulation of
hydrogen
ISO/TS 15916:2026(en)
3.17
convection current
motion or circulation of a fluid involving the transport of mass from one location to another driven by
temperature dependent density gradients
Note 1 to entry: See natural convection (3.66).
3.18
cryogenic fluid
refrigerated liquefied gas
gas that is partially liquid because of its low temperature
Note 1 to entry: This includes totally evaporated liquids and supercritical fluids.
Note 2 to entry: The 13th International Institute of Refrigeration's (IIR) International Congress of Refrigeration (held
in Washington DC in 1971) endorsed a universal definition of "cryogenics" and "cryogenic" by accepting a threshold of
120 K (−153 °C) to distinguish these terms from conventional refrigeration.
[SOURCE: ISO 21009-1: 2022 clause 3.4, modified – removal of Note 2 to entry, and inclusion of a replacement
Note 2 to entry]
3.19
cryo-pumping
process that consists of cooling a surface to a temperature of less than 120 K so that gases and vapours
condense on the surface
Note 1 to entry: This process, though usually undesirable in the context here, is also used as a vacuum pump.
3.20
deflagration
combustion process in which a flame or chemical reaction moves through a flammable mixture at a rate less
than the speed of sound in the unburned mixture
Note 1 to entry: Fast deflagrations are characterized by velocities in the hundreds of metres per second, and their
effects do not differ much from those of a detonation (3.23).
Note 2 to entry: Laminar deflagration waves are characterized by velocities in the several metres per second and do
not cause significant over pressures in the open.
3.21
deflagration-to-detonation-transition
DDT
event, often caused by turbulence, in which a deflagration (3.20) initiates a detonation (3.23)
3.22
deluge system
water spray system that is used to keep equipment, especially hydrogen storage vessels, cool in the event of
a fire
3.23
detonation
shock stabilized combustion process resulting in a combustion phenomenon propagating faster than the
speed of sound
Note 1 to entry: A detonation is an explosion, but the reverse is not true.
Note 2 to entry: The thermal energy of the reaction sustains the shock wave, and the shock wave compresses unreacted
material, producing the high temperatures necessary to drive the reaction.
3.24
detonation cell
fundamental part of the mechanism for energy release within a detonation (3.23)

ISO/TS 15916:2026(en)
Note 1 to entry: The spatial arrangement of the shock front and acoustic waves moving behind and transverse to the
shock front defines a cellular region of combustion that is observed experimentally as a “fish-scale” shaped track on
sooted foils exposed to the detonation.
Note 2 to entry: The width of this diamond shape denotes the cell size, and its length can be empirically related to
the formulae that can predict the energy required to directly initiate detonation and the physical dimensions of the
structures that prohibit detonation.
3.25
detonation limits
maximum and minimum concentrations of a gas, vapour, mist, spray or dust, in air or oxygen, for stable
detonation (3.23) to occur
Note 1 to entry: The limits are in reality controlled not only by the concentration of the mixture but also by the size
and geometry of the environment as well as the means by which ignition occurs. There is no standard procedure for
their determination.
Note 2 to entry: See flammability limits (3.45)
3.26
deuterium
D
H
isotope of hydrogen with a nucleus containing one neutron and one proton and a mass number of two
3.27
diffusion
flux of a fluid through another fluid or material due to concentration gradient
EXAMPLE The motion of hydrogen gas through air, or the movement of hydrogen gas through the wall of a rubber
hose.
Note 1 to entry: The diffusion coefficient is the mass of material diffusing across a unit of area in a unit of time at a unit
concentration gradient.
3.28
diluent
inert component within a gas mixture that reduces the concentration of the remaining (active) materials
3.29
dual-fault tolerance
system design in which the failure of two elements to perform as intended does not cause an entire system
to function unpredictably or catastrophically
Note 1 to entry: The faults can be in two related areas or two areas that function completely independently, and the
system should continue to function as intended.
3.30
ductility
percentage elongation to failure or the reduction in cross-sectional area of a specimen in a
simple tensile test
Note 1 to entry: Materials can make a ductile-to-brittle transition at low temperatures.
3.31
electrolyser
device that performs electrolysis (3.32)
3.32
electrolysis
process in which electric current is used to promote a chemical reaction
Note 1 to entry: In the case of water, an example is the separation of hydrogen from oxygen.

ISO/TS 15916:2026(en)
3.33
...