FprCEN/TR 17924

SLOVENSKI STANDARD
01-november-2024
Varnostne in nadzorne naprave za gorilnike in aparate na plin in/ali tekoča goriva -
Navodilo o posebnih vidikih, značilnih za vodik
Safety and control devices for burners and appliances burning gaseous and/or liquid
fuels - Guidance on hydrogen specific aspects
Sicherheits- und Regeleinrichtungen für Brenner und Brennstoffgeräte für gasförmige
und/oder flüssige Brennstoffe - Leitfaden zu wasserstoffspezifischen Aspekten
Dispositifs de sécurité et de contrôle des brûleurs et des appareils brûlant des
combustibles gazeux et/ou liquides - Orientations concernant les aspects spécifiques à
l'hydrogène
Ta slovenski standard je istoveten z: FprCEN/TR 17924
ICS:
23.060.40 Tlačni regulatorji Pressure regulators
27.060.01 Gorilniki in grelniki vode na Burners and boilers in
splošno general
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

FINAL DRAFT
TECHNICAL REPORT
RAPPORT TECHNIQUE
TECHNISCHER REPORT
October 2024
ICS 23.060.40 Will supersede CEN/TR 17924:2023
English Version
Safety and control devices for burners and appliances
burning gaseous and/or liquid fuels - Guidance on
hydrogen specific aspects
Dispositifs de sécurité et de contrôle des brûleurs et Sicherheits- und Regeleinrichtungen für Brenner und
des appareils brûlant des combustibles gazeux et/ou Brennstoffgeräte für gasförmige und/oder flüssige
liquides - Orientations concernant les aspects Brennstoffe - Leitfaden zu wasserstoffspezifischen
spécifiques à l'hydrogène Aspekten

This draft Technical Report is submitted to CEN members for Vote. It has been drawn up by the Technical Committee CEN/TC 58.

CEN members are the national standards bodies 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.
Recipients of this draft are invited to submit, with their comments, notification of any relevant patent rights of which they are
aware and to provide supporting documentation.

Warning : This document is not a Technical Report. It is distributed for review and comments. It is subject to change without
notice and shall not be referred to as a Technical Report.

EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2024 CEN All rights of exploitation in any form and by any means reserved Ref. No. FprCEN/TR 17924:2024 E
worldwide for CEN national Members.

Contents Page
European foreword . 4
Introduction . 5
1 Scope . 6
2 Normative references . 7
3 Terms and definitions . 7
4 Classification. 8
4.1 Classes of control . 8
4.2 Classification of hydrogen . 8
5 Common properties . 10
6 General considerations regarding design and construction . 12
6.1 Mechanical parts of the control . 12
6.1.1 Theoretical background . 12
6.1.2 Holes . 14
6.1.3 Breather holes . 14
6.2 Materials . 29
6.2.1 General material requirements . 29
6.2.2 Housing . 30
6.2.3 Zinc alloys . 32
6.2.4 Springs . 32
6.2.5 Resistance to corrosion and surface protection . 32
6.3 Electrical parts of the control . 32
6.3.1 Electrical components . 32
7 Performance . 33
7.1 Leak-tightness . 33
7.1.1 Laminar flow model and calculations . 33
7.1.2 Leakage rate measurements and calculations . 34
7.1.3 Conclusions on leakage rate measurements and calculations . 36
7.1.4 Considerations based on risk assessment . 36
7.2 Durability . 41
7.2.1 Elastomers in contact with gas . 41
7.2.2 Lubricants in contact with gas . 41
8 Marking, instructions . 42
8.1 Instructions . 42
Annex A (informative) Modifications and/or additions to subclauses of CEN/TC 58/WG 11
standards due to introduction of hydrogen admixtures as combustible gas. 43
Annex B (informative) Modifications and/or additions to subclauses of CEN/TC 58/WG 12
standards due to introduction of hydrogen admixtures as combustible gas. 44
Annex C (informative) Modifications and/or additions to subclauses of CEN/TC 58/WG 13
standards due to introduction of hydrogen admixtures as combustible gas. 47
Annex D (informative) Modifications and/or additions to subclauses of CEN/TC 58/WG 14
standards due to introduction of hydrogen admixtures as combustible gas. 48
Annex E (informative) Risk assessment, standardization, certification, and operation of gas
appliances with admixtures fluctuating up to 20 vol.-% hydrogen to natural gas . 49
Annex F (informative) Risk assessment, standardization, certification, and operation of gas
appliances using hydrogen referring to ISO 14687:2019, Type I, Grade A . 54
F.1 General . 54
F.2 Hydrogen Grade A and impurities: Risk analysis concerning CO thermal overload . 60
F.3 Reaction equations which explain carbon monoxide formation . 61
F.3.1 Hydrogen . 61
F.3.2 Methane, ethane, and propane . 61
F.4 Conclusions for carbon monoxide and thermal loads . 62
Annex G (informative) Proposal for leakage rate requirements and tests for gas pipe work
including controls (e. g., valves, regulators, pressure switches) used in gas appliances
(e. g., forced draught gas-burners or industrial thermo-processing equipment) and
the impact on the installation room size . 63
Annex H (informative) Diaphragm fracture or fracture of non-metallic parts leakage rate
mitigation measures . 75
Annex I (informative) Leakage rate mitigation measures . 82
Bibliography . 86

European foreword
This document (FprCEN/TR 17924:2024) has been prepared by Technical Committee CEN/TC 58 “Safety
and control devices for burners and appliances burning gaseous or liquid fuels”, the secretariat of which
is held by BSI.
This document is currently submitted to the Vote on TR.

Introduction
The use of hydrogen as a renewable fuel next to biomethane is seen as a promising alternative to natural
gas soon. As soon as the according regulations and standards are in force, the use of hydrogen can be
expected on a more regular basis.
For this reason, the heating and combustion business have to provide suitable solutions based on
standardized safety, construction, and performance requirements.
This document provides a summary of considerations regarding safety and performance aspects for
safety and control devices which will in some cases require further research.
There are research projects on the use of hydrogen admixture with natural gas in various percentages or
as hydrogen like the European THyGA project (up to 60 vol.-% hydrogen fluctuating admixtures to
natural gas).
Therefore, this document is written in preparation of future revisions of CEN/TC 58 documents and will
describe findings pointing at potential changes, give the according research backgrounds and provide
literature sources.
This document includes evaluations regarding different gases, comparing their distinctive
characteristics, properties, and their impact on the risk assessment for gas appliances. Theoretical
evaluations are complemented by laboratory measurements.
For the future implementation of hydrogen in the whole value chain co-operation with other CEN/TCs is
necessary like e. g., CEN/TC 234 “Gas infrastructure”, CEN/TC 109 “Central heating boilers using gaseous
fuels”, CEN/TC 131 “Gas burners using fans”, and CEN/TC 186 “Industrial thermoprocessing — Safety”.
This document up to Annex A is based on the structure of EN 13611:2019.
In this document only those clauses of EN 13611:2019 are referred to, which can be affected by using
hydrogen or hydrogen admixtures as gaseous fuels. All other clauses, which can be not affected, are not
listed in this document.
For the calculations and measurements in this document the specific admixture of 20 vol.-% hydrogen
and 80 vol.-% methane is used. This admixture is already used as a typical reference in other standards.
1 Scope
This document is written in preparation of future revision of standards dealing with the general safety,
design, construction, and performance requirements and testing of safety, control or regulating devices
(hereafter referred to as controls) for burners and appliances burning hydrogen (see 3.2) or hydrogen
admixtures (see 3.3).
This document refers to controls with declared maximum inlet pressure up to and including 500 kPa and
of nominal connection sizes up to and including DN 250.
The purpose of this document is to provide guidance on hydrogen specific topics, which need to be
considered in the future standardization of controls covered by CEN/TC 58 documents including:
— automatic shut-off valves;
— automatic burner control systems;
— flame supervision devices;
— gas/air ratio controls;
— pressure regulators;
— manual taps;
— mechanical thermostats;
— multifunctional controls;
— pressure sensing devices;
— valve proving systems;
— automatic vent valves.
Hydrogen will play a significant role in the future in several energy segments and requirements and test
methods need to be verified and adapted, if
...