prEN 16726

SLOVENSKI STANDARD
01-januar-2024
Infrastruktura za plin - Kakovost plina - Skupina H
Gas infrastructure - Quality of gas - Group H
Gasinfrastruktur - Beschaffenheit von Gas - Gruppe H
Infrastructures gazières - Qualité du gaz - Groupe H
Ta slovenski standard je istoveten z: prEN 16726
ICS:
75.060 Zemeljski plin Natural gas
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

DRAFT
EUROPEAN STANDARD
NORME EUROPÉENNE
EUROPÄISCHE NORM
December 2023
ICS 75.060 Will supersede EN 16726:2015+A1:2018
English Version
Gas infrastructure - Quality of gas - Group H
Infrastructures gazières - Qualité du gaz - Groupe H Gasinfrastruktur - Beschaffenheit von Gas - Gruppe H
This draft European Standard is submitted to CEN members for enquiry. It has been drawn up by the Technical Committee
CEN/TC 234.
If this draft becomes a European Standard, CEN members are bound to comply with the CEN/CENELEC Internal Regulations
which stipulate the conditions for giving this European Standard the status of a national standard without any alteration.

This draft European Standard was established by CEN in three official versions (English, French, German). A version in any other
language made by translation under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC
Management Centre has the same status as the official versions.

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 European Standard. It is distributed for review and comments. It is subject to change without
notice and shall not be referred to as a European Standard.

EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2023 CEN All rights of exploitation in any form and by any means reserved Ref. No. prEN 16726:2023 E
worldwide for CEN national Members.

Contents Page
European foreword . 4
Introduction . 5
1 Scope . 6
2 Normative references . 6
3 Terms and definitions . 6
4 Reference conditions and pressure units . 10
5 Requirements . 10
5.1 Requirements to the gas quality . 10
5.2 Entry point Wobbe Index range (recommendation) . 13
5.3 Exit point Wobbe Index classification . 13
5.3.1 General. 13
5.3.2 Definition of classes . 14
5.3.3 Class ‘Specified’ . 15
5.3.4 Class ‘Extended’ . 16
5.3.5 Acceptable deviation from a defined class . 17
5.3.6 Transition period for implementation of Wobbe Index classification . 18
5.4 Effects of the injection of hydrogen onto gas quality . 18
5.5 Sampling . 18
Annex A (normative)  Calculation of methane number of gaseous fuels for engines . 19
A.1 Introduction . 19
A.2 Calculation of methane number . 19
A.3 Example 1: 2H-gas . 20
A.4 Example 2: enriched biomethane . 26
A.5 Example 3: 2H-gas with hydrogen addition . 27
Annex B (informative) Oxygen . 41
B.1 Origin of oxygen . 41
B.2 Challenges related to oxygen in gas . 41
B.3 Mitigation possibilities . 42
B.4 Oxygen measurement . 42
Annex C (informative) Sulfur . 43
C.1 General. 43
C.2 Total sulfur from Odorants . 43
Annex D (informative) Water dew point and hydrocarbon dew point. 47
D.1 Water dew point . 47
D.2 Hydrocarbon dew point . 47
Annex E (informative) Hydrogen . 48
Annex F (informative) Methane Number . 50
Annex G (informative) Possible mitigation measures for Wobbe Index changes . 51
Annex H (informative) Limitations of the end-use gas applications to cope with the broad
Wobbe Index entry range . 53
Annex I (informative) General considerations on adjustment and re-adjustment of
residential and commercial appliances . 54
I.1 Basics . 54
I.2 On-site adjustment today . 58
I.3 Virtual readjustment to G20 in the field . 58
I.4 Advantages and dis-advantages of “virtual adjustment” . 63
Annex J (informative) On-site adjustment of the end-use applications related to the Wobbe
Index exit proposal . 64
J.1 General . 64
J.2 Combustion . 64
J.3 Combustion settings . 65
J.4 On-site adjustment of combustion settings. 66
J.5 On-site adjustment vs. Wobbe Index classes assigned to exit points . 66
J.6 Auto-adaptive control of combustion settings . 68
Annex K (informative) Some legal definitions which are considered useful for the topic of
this document . 69
Annex L (informative) A-deviations . 71
Bibliography . 72

European foreword
This document (prEN 16726:2023) has been prepared by Technical Committee CEN/TC 234 “Gas
infrastructure”, the secretariat of which is held by DIN.
This document is currently submitted to CEN Enquiry.
This document will supersede EN 16726:2015+A1:2018.
In comparison with the previous edition, the following technical modifications have been made:
— Inclusion of a Wobbe Index requirement (5.3), i.e. Wobbe Index exit classification requirement and
a Wobbe Index entry recommendation and related informative Annexes:
o Annex H - Limitations of the end-use gas applications to cope with the broad Wobbe Index
entry range;
o Annex I - General considerations on adjustment and re-adjustment of residential and
commercial appliances;
o Annex J - Onside adjustment of end-use applications;
— Addition of an admissible hydrogen concentration (subclause 5.1, Table 1) and related informative
Annex E;
— Revision of the minimum relative density (subclause 5.1, Table 1);
— Revision of the admissible oxygen content (subclause 5.1, Table 1) and addition of related
informative Annex B;
— Revision of the admissible sulfur content (subclause 5.1, Table 1) and addition of related
informative Annex C;
— Clarification on the admissible methane number in this standard (subclause 5.1, Table 1 Note g) in
relation to the general design of engines and addition of related informative Annex F.
This document has been prepared under a standardization request addressed to CEN by the European
Commission. The Standing Committee of the EFTA States subsequently approves these requests for its
Member States.
The need for a European Standard concerning the specification of the quality of gases of group H is
derived from the standardization request M/400 issued to CEN by the European Commission.
According to this standardization request the goal is to define specifications that are as wide as possible
within reasonable costs. This means that the specifications enhance the free flow of gas within the
internal EU market, in order to promote competition and security of supply minimizing the negative
effects on gas infrastructure and gas networks, efficiency and the environment and allow appliances to
be used without compromising safety.
Some requirements specified in this European Standard, Clause 5, cannot be implemented by xyz due to
existing conflicting national legislation. The related A-Deviations are listed in Annex L (to be verified
during Public Enquiry).
Introduction
This document sets requirements for gas quality with the aim to allow the free flow of gas between the
CEN member states and to enable the security of supply taking into account the impact on the whole
value chain from gas production and supply to end uses.
The Wobbe Index requirements in this document are based on the proposal of the CEN Sector Forum
Gas Joint Working Group Pre-normative studies of H-gas quality parameters (CEN SFGas GQS).
NOTE Responsibility and liability issues in the context of this document are subject to European or national
regulations.
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