20/30401719 DC - BS EN 257. Mechanical thermostats for gas-burning appliances
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20/30401719 DC

BS EN 257. Mechanical thermostats for gas-burning appliances

Status : Current, Draft for public comment   Published : May 2020



This document 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 document 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 document applies to thermostats controlling the gas flow directly or indirectly through an integral gas valve.

This document only applies to thermostats used with gas appliances which are not installed in the open air.

Thermostats dealt with in this document are intended for control functions.

This document is not applicable to:

  1. the thermocouple;

  2. controls which use auxiliary energy (e.g. electrical energy supplied externally);

  3. an assessment of the control regarding Performance Level (PL) and Safety Integrity Level (SIL).

Standard Number20/30401719 DC
TitleBS EN 257. Mechanical thermostats for gas-burning appliances
StatusCurrent, Draft for public comment
Publication Date07 May 2020
Normative References(Required to achieve compliance to this standard)EN 13611:2019
Informative References(Provided for Information)EN 13611:2019
International RelationshipsprEN 257
Draft Expiry Date30 June 2020
DescriptorsGas valves, Instructions for use, Thermal-cycling tests, Valves, Marking, Controllers, Temperature controllers, Control equipment, Testing conditions, Gas-powered devices, Flow regulators, Flow rates, Thermostats, Performance testing, Mechanically-operated devices, Leak tests, Design, Thermal testing, Performance
Title in FrenchThermostats mécaniques pour appareils à gaz
Title in GermanMechanische Temperaturregler für Gasgeräte
File Size435 KB
NotesWarning: this draft is not current beyond its expiry date for comments.

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