SIST EN 257:2022
(Main)Mechanical thermostats for gas-burning appliances
Mechanical thermostats for gas-burning appliances
This European Standard specifies the safety, construction and performance requirements for mechanical thermostats intended for use with gas appliances and similar use, hereafter referred to as ‘thermostats’.
This European Standard applies to thermostats with declared maximum inlet pressures up to and including 50 kPa (500 mbar) of nominal connection sizes up to and including DN 50 for use with one or more fuel gases in accordance with EN 437.
This European Standard applies to thermostats controlling the gas flow directly or indirectly through an integral gas valve, and which do not require external electrical energy for their operation.
This European Standard only applies to thermostats used with gas appliances which are not installed in the open air.
Thermostats dealt with in this European Standard are intended for control functions.
Mechanische Temperaturregler für Gasgeräte
Dieses Dokument legt die Anforderungen an die Sicherheit, konstruktive Ausführung und Funktion von mechanischen Temperaturreglern fest, im Folgenden als „Temperaturregler“ bezeichnet, die für die Verwendung mit Gasgeräten und ähnliche Verwendungszwecke vorgesehen sind.
Dieses Dokument gilt für Temperaturregler mit Nenn-Anschlussmaßen bis einschließlich DN 50 mit einem höchsten angegebenen Eingangsdruck bis einschließlich 50 kPa (500 mbar) für die Verwendung mit einem oder mehreren Brenngasen nach EN 437.
Dieses Dokument gilt für Temperaturregler, die den Gasstrom direkt oder indirekt durch ein eingebautes Gasventil steuern.
Dieses Dokument gilt nur für Temperaturregler, die in Gasgeräten verwendet werden, die nicht im Freien aufgestellt sind.
Die in diesem Dokument behandelten Temperaturregler sind für Regel- und Steuerfunktionen vorgesehen.
Dieses Dokument ist nicht anwendbar auf:
a) das Thermoelement;
b) Regel- und Steuergeräte, die Hilfsenergie nutzen (z. B. von außen zugeführte elektrische Energie);
c) eine Bewertung der Regeleinrichtung in Bezug auf Performance Level (PL) und Sicherheits-Integritätslevel (SIL).
Thermostats mécaniques pour appareils à gaz
L’article 1 de la norme EN13611 :2019 s’applique avec la modification et l’addition suivantes :
Modification :
Le 1er paragraphe de l’article 1 de la norme EN 13611:2019 est remplacé par ce qui suit :
Le présent document spécifie les caractéristiques de sécurité, de construction et de fonctionnement ainsi que les essais applicables aux thermostats mécaniques équipant les appareils utilisant des combustibles gazeux et d'utilisation similaire, ci-après désignés « thermostats ».
Ce document s'applique aux thermostats de pression amont maximale déclarée inférieure ou égale à 50 kPa , de diamètre nominal de raccordement inférieur ou égal à DN 50 et utilisés avec un ou plusieurs combustibles gazeux.
Addition :
Ce document est applicable aux thermostats qui contrôlent le débit du gaz directement ou indirectement au moyen d'une vanne de gaz intégrée. Il s'applique seulement aux thermostats utilisés sur des appareils utilisant des combustibles gazeux qui ne sont pas installés en plein air.
Les thermostats visés par le présent document assurent des fonctions de régulation.
Ce document ne s'applique pas :
a) aux équipements utilisant une énergie auxiliaire (par exemple, alimentation en énergie électrique externe) ;
b) à une évaluation du niveau de performance (PL) et du niveau d'intégrité de sécurité (SIL) de l'équipement.
Le 4ième paragraphe de l’article 1 de la EN 13611 :2019 est supprimé.
Mehanski termostati za plinske aparate
General Information
Relations
Standards Content (Sample)
SLOVENSKI STANDARD
01-december-2022
Nadomešča:
SIST EN 257:2010
Mehanski termostati za plinske aparate
Mechanical thermostats for gas-burning appliances
Mechanische Temperaturregler für Gasgeräte
Thermostats mécaniques pour appareils à gaz
Ta slovenski standard je istoveten z: EN 257:2022
ICS:
17.200.20 Instrumenti za merjenje Temperature-measuring
temperature instruments
27.060.20 Plinski gorilniki Gas fuel burners
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
EN 257
EUROPEAN STANDARD
NORME EUROPÉENNE
October 2022
EUROPÄISCHE NORM
ICS 27.060.20 Supersedes EN 257:2010
English Version
Mechanical thermostats for gas-burning appliances
Thermostats mécaniques pour appareils à gaz Mechanische Temperaturregler für Gasgeräte
This European Standard was approved by CEN on 8 August 2022.
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. Up-to-date lists and bibliographical references
concerning such national standards may be obtained on application to the CEN-CENELEC Management Centre or to any CEN
member.
This European Standard exists 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.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2022 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN 257:2022 E
worldwide for CEN national Members.
Contents Page
European foreword . 4
Introduction . 5
1 Scope . 7
2 Normative references . 7
3 Terms and definitions . 7
4 Classification . 9
4.1 Classes of control . 9
4.2 Groups of control. 9
4.3 Classes of control functions . 9
4.4 Types of DC supplied controls . 10
5 Test conditions and uncertainty of measurements . 10
6 Design and construction . 10
6.1 General . 10
6.2 Mechanical parts of the control . 10
6.3 Materials. 11
6.4 Gas connections . 11
6.5 Electrical parts of the control . 11
6.6 Protection against internal faults for the purpose of functional safety . 11
6.101 Flow characteristics . 11
6.102 Temperature adjustment . 11
7 Performance . 12
7.1 General . 12
7.2 Leak-tightness . 13
7.3 Torsion and bending . 13
7.4 Rated flow rate . 13
7.5 Durability . 14
7.6 Performance tests for electronic controls . 14
7.7 Long-term performance for electronic controls . 14
7.8 Data exchange . 14
7.101 Calibration temperature set-point . 14
7.102 Backlash . 14
7.103 Opening of a snap-acting thermostat with a closed position . 15
7.104 Opening pressure and closing pressure for thermostats with a closed position . 15
7.105 Operating characteristic of the thermostat . 15
7.106 Ambient temperature range of the body . 19
7.107 Effect of storage and transport temperatures . 19
7.108 Thermal overload of the temperature sensor . 20
7.109 Operating torque of the thermostat set-point adjuster . 20
7.110 Endurance . 20
8 Electrical requirements . 22
9 Electromagnetic compatibility (EMC) . 22
10 Marking, instructions . 22
10.1 Marking . 22
10.2 Instructions. 22
10.3 Warning notice . 23
Annex A (informative) Abbreviations and Symbols . 24
Annex B (informative) Leak-tightness tests for gas controls – volumetric method . 25
Annex C (informative) Leak-tightness tests for gas controls – pressure loss method . 26
Annex D (normative) Conversion of pressure loss into leakage rate . 27
Annex E (normative) Electrical/electronic component fault modes . 28
Annex F (normative) Additional requirements for safety accessories and pressure
accessories as defined in EU Directive 2014/68/EU . 29
Annex G (normative) Materials for pressurized parts . 30
Annex H (normative) Additional materials for pressurized parts . 31
Annex I (normative) Requirements for controls used in DC supplied burners and
appliances burning gaseous or liquid fuels . 32
Annex J (normative) Method for the determination of the Safety Integrity Level (SIL) . 33
Annex K (normative) Method for the determination of a Performance Level (PL) . 34
Annex L (informative) Relationship between Safety Integrity Level (SIL) and
Performance Level (PL) . 35
Annex M (normative) Reset functions . 36
Annex N (informative) Guidance document on Environmental Aspects . 37
Annex O (normative) Seals of elastomers, cork and synthetic fibre mixtures . 38
Annex ZA (informative) Relationship between this European Standard and the essential
requirements of Regulation (EU) 2016/426 aimed to be covered . 39
Bibliography . 42
European foreword
This document (EN 257:2022) 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 European Standard shall be given the status of a national standard, either by publication of an
identical text or by endorsement, at the latest by April 2023, and conflicting national standards shall be
withdrawn at the latest by October 2025.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CEN shall not be held responsible for identifying any or all such patent rights.
This document supersedes EN 257:2010.
The following significant changes compared to the previous edition have been incorporated in this
document:
a) alignment with EN 13611:2019;
b) requirements from EU Directive 2014/68/EU were not adopted;
c) updating of Clause 2, normative references;
d) reference to EN 437 removed;
e) information on life time for safe function (designed lifetime) added to instructions.
This document has been prepared under a Standardization Request given to CEN by the European
Commission and the European Free Trade Association, and supports essential requirements of
EU Directive(s) / Regulation(s).
For relationship with EU Directive(s) / Regulation(s), see informative Annex ZA, which is an integral part
of this document.
Any feedback and questions on this document should be directed to the users’ national standards body.
A complete listing of these bodies can be found on the CEN website.
According to the CEN-CENELEC Internal Regulations, the national standards organisations of the
following countries are bound to implement this European Standard: 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.
Introduction
This document is intended to be used in conjunction with EN 13611:2019.
EN 13611:2019 recognizes the safety level specified by CEN/TC 58 and is regarded as a horizontal
standard dealing with the safety, construction, performance and testing of controls for burners and
appliances burning gaseous and/or liquid fuels.
The general requirements for controls are given in EN 13611:2019, and methods for classification and
assessment for new controls and control functions are given in EN 14459:2021 (see Figure 1).
EN 126:2012 (see Figure 1) specifies multifunctional controls combining two or more controls and
Application Control Functions, one of which is a mechanical control function. The requirements for
controls and Application Control Functi
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