1、raising standards worldwideNO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAWBSI Standards PublicationBS EN 257:2010Mechanical thermostats forgas-burning appliancesBS EN 257:2010 BRITISH STANDARDNational forewordThis British Standard is the UK implementation of EN 257:2010. Itsup
2、ersedes BS EN 257:1992 which is withdrawn.The UK participation in its preparation was entrusted to TechnicalCommittee GSE/22, Safety and control devices for gas and oilburners and gas burning appliances.A list of organizations represented on this committee can beobtained on request to its secretary.
3、This publication does not purport to include all the necessaryprovisions of a contract. Users are responsible for its correctapplication. BSI 2010ISBN 978 0 580 63335 5ICS 27.060.20; 97.120Compliance with a British Standard cannot confer immunity fromlegal obligations.This British Standard was publi
4、shed under the authority of theStandards Policy and Strategy Committee on 31 July 2010Amendments issued since publicationDate Text affectedBS EN 257:2010EUROPEAN STANDARD NORME EUROPENNE EUROPISCHE NORM EN 257 June 2010 ICS 27.060.20 Supersedes EN 257:1992English Version Mechanical thermostats for g
5、as-burning appliances Thermostats mcaniques pour appareils gaz Mechanische Temperaturregler fr Gasgerte This European Standard was approved by CEN on 19 May 2010. CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European Standar
6、d 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 Management Centre or to any CEN member. This European Standard exists in three official versions (English, French,
7、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 Management Centre has the same status as the official versions. CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cy
8、prus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom. EUROPEAN COMMITTEE FOR STANDARDIZATION
9、COMIT EUROPEN DE NORMALISATION EUROPISCHES KOMITEE FR NORMUNG Management Centre: Avenue Marnix 17, B-1000 Brussels 2010 CEN All rights of exploitation in any form and by any means reserved worldwide for CEN national Members. Ref. No. EN 257:2010: EBS EN 257:2010EN 257:2010 (E) 2 Contents Page Forewo
10、rd 41 Scope 52 Normative references 53 Terms and definitions .54 Classification 75 Units of measurement and test conditions .76 Construction requirements .77 Performance 108 EMC/Electrical requirements . 209 Marking, installation and operating instructions 21Annex A (informative) Gas connections in
11、common use in the various countries . 23Annex B (informative) Leak-tightness test volumetric method 24Annex C (informative) Leak-tightness test pressure loss method . 25Annex D (normative) Conversion of pressure loss into leakage rate . 26Annex E (normative) Electrical/electronic component fault mod
12、es 27Annex F (normative) Additional requirements for safety accessories and pressure accessories as defined in EU Directive 97/23/EC 28Annex G (normative) Materials for pressurized parts . 29Annex H (informative) Additional materials for pressurized parts 30Annex I (normative) Requirements for contr
13、ols used in DC supplied gas burners and gas burning appliances . 31Annex ZA (informative) Relationship between this European Standard and the Essential Requirements of EU Directive 2009/142/EC relating to appliances burning gaseous fuels . 32Bibliography . 34BS EN 257:2010EN 257:2010 (E) 3 Figures F
14、igure 1 Thermostat test apparatus . 16 Figure 2 Typical operating characteristics of a thermostat over a range of temperature set-point adjustments . 17 Tables Table 1 Sequence of testing 10Table 2 Maximum leakage rates 12Table 3 Exceptions for thermal overload . 18Table 4 Number of mechanical cycle
15、s . 20Table ZA.1 Correspondence between this European Standard and Directive 2009/142/EC relating to appliances burning gaseous fuels . 32BS EN 257:2010EN 257:2010 (E) 4 Foreword This document (EN 257:2010) has been prepared by Technical Committee CEN/TC 58 “Safety and control devices for burners an
16、d 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 December 2010, and conflicting national standards shall be w
17、ithdrawn at the latest by December 2010. Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. CEN and/or CENELEC shall not be held responsible for identifying any or all such patent rights. This document has been prepared under a manda
18、te given to CEN by the European Commission and the European Free Trade Association, and supports essential requirements of EU Directive. For relationship with EU Directive, see informative Annex ZA, which is an integral part of this document. This document supersedes EN 257:1992. This European Stand
19、ard is intended to be used in conjunction with EN 13611:2007. This document refers to clauses of EN 13611:2007 or adapts clauses by stating “with the following modification”, “with the following addition”, “is replaced by the following” or “is not applicable“ in the corresponding clause. This Europe
20、an Standard adds clauses or sub clauses to the structure of EN 13611:2007 which are particular to this European Standard. It should be noted that these clauses and sub-clauses are not indicated as an addition. It should be noted that the following significant technical changes compared to the previo
21、us edition have been incorporated in this European Standard: a) scope is enlarged to maximum inlet pressures up to and including 50 kPa (500 mbar); b) alignment with EN 13611:2007; c) updating of Clause 2, normative references; d) units of measurement and test conditions are updated according to EN
22、13611:2007; e) requirements and tests concerning durability of elastomers in contact with gas (7.8 of this European Standard) are now totally aligned with EN 13611:2007, 7.8; f) marking, installation and operating instructions (Clause 9 of this European Standard) are extended to cover additional inf
23、ormation. According to the CEN/CENELEC Internal Regulations, the national standards organizations 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, Icelan
24、d, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom. BS EN 257:2010EN 257:2010 (E) 5 1 Scope This European Standard specifies the safety, construction and performance requirements f
25、or 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 us
26、e 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 thermo
27、stats used with gas appliances which are not installed in the open air. Thermostats dealt with in this European Standard are intended for control functions. 2 Normative references The following referenced documents are indispensable for the application of this document. For dated references, only th
28、e edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. EN 13611:2007, Safety and control devices for gas burners and gas-burning appliances General require-ments 3 Terms and definitions For the purposes of this document, the
29、 terms and definitions given in EN 13611:2007 and the following apply. 3.101 mechanical thermostat thermostat which controls the temperature by adjusting the flow rate accordingly to the temperature of the sensor without any external energy, such that the temperature remains within defined limits 3.
30、102 adjustable thermostat mechanical thermostat in which the temperature set-point can be adjusted by the user to anywhere between minimum and maximum values 3.103 fixed setting thermostat mechanical thermostat that has a preset fixed operating temperature which cannot be adjusted by the user 3.104
31、snap-acting thermostat mechanical thermostat with only two positions for the flow rate, i.e. full on-off, full on-reduced rate or reduced rate-off 3.105 modulating thermostat mechanical thermostat which controls the flow rate in accordance with a predetermined and continuous function of the temperat
32、ure of the temperature sensor BS EN 257:2010EN 257:2010 (E) 6 3.106 modulating thermostat with additional on-off action mechanical thermostat which acts as a snap-acting thermostat between the closed and reduced positions and as a modulating thermostat between the reduced and full-on positions 3.107
33、 thermostat closure member movable part of the thermostat which opens and closes the gas way and/or varies the flow rate 3.108 presetting device device for adjusting an operating condition only by an authorized person NOTE It may be fixed or variable, e.g. when it is the gas flow that is adjustable,
34、 either an orifice or an adjusting screw may be used. 3.109 fixed bypass non-adjustable presetting device for fixing the minimum gas flow through a thermostat 3.110 bypass adjusting device screw adjustment or an exchangeable orifice, that fixes the minimum gas flow rate through the thermostat, and w
35、hich is accessible only by the use of tools 3.111 temperature sensor device which senses the temperature of the medium to be controlled or to be supervised 3.112 operating curve graphical representation of the flow rate as a function of the sensor temperature at a given temperature set-point and at
36、a constant inlet pressure 3.113 backlash difference of position of the adjusting knob when it is moved in both directions to obtain the same flow rate at a constant sensor temperature 3.114 adjusting knob (or spindle) part of the thermostat which is used to select the temperature set-point 3.115 tem
37、perature set-point any value selected within the temperature range at which the controlled temperature should be maintained 3.116 temperature set-point range range between the minimum and maximum adjustable temperature set-points (by means of the adjusting knob) 3.117 calibration flow rate flow rate
38、 declared by the manufacturer for calibration 3.118 calibration temperature set-point temperature at which the calibration flow rate should be obtained with the adjustment set to the position and in the direction declared by the manufacturer BS EN 257:2010EN 257:2010 (E) 7 3.119 temperature differen
39、tial for snap-acting thermostats difference in temperature necessary to obtain a change in the flow rate, at a given set-point 3.120 deviation maximum deviation from the temperature set-point which is declared by the manufacturer 3.121 drift permanent change in the operating curve of the thermostat
40、4 Classification 4.1 Classes of control EN 13611:2007, 4.1 is not applicable. 4.2 Groups of control Shall be according to EN 13611:2007, 4.2. 4.3 Classes of control functions EN 13611:2007, 4.3 is not applicable. 5 Units of measurement and test conditions Shall be according to EN 13611:2007, Clause
41、5. 6 Construction requirements 6.1 General Shall be according to EN 13611:2007, 6.1. 6.2 Mechanical parts of the control 6.2.1 Appearance Shall be according to EN 13611:2007, 6.2.1. 6.2.2 Holes Shall be according to EN 13611:2007, 6.2.2. 6.2.3 Breather holes Shall be according to EN 13611:2007, 6.2.
42、3. BS EN 257:2010EN 257:2010 (E) 8 6.2.4 Test for leakage of breather holes Shall be according to EN 13611:2007, 6.2.4. 6.2.5 Screwed fastenings Shall be according to EN 13611:2007, 6.2.5. 6.2.6 Jointing Shall be according to EN 13611:2007, 6.2.6. 6.2.7 Moving parts Shall be according to EN 13611:20
43、07, 6.2.7. 6.2.8 Sealing caps Shall be according to EN 13611:2007, 6.2.8. 6.2.9 Dismantling and reassembly Shall be according to EN 13611:2007, 6.2.9 with the following addition: If, in accordance with the manufacturers instructions the thermostat can be dismantled for servicing, such action shall n
44、ot result in a change in temperature calibration exceeding the declared maximum set point deviation (see 7.101.1). 6.2.101 Presetting devices A presetting device shall only be adjustable by use of a tool. The means of adjustment shall be easily accessible and shall not change of its own accord, but
45、shall be protected against unauthorized interference, e.g. use of a sealing (lacquer). A presetting device which connects a gas-carrying part to atmosphere shall be made sound by a means which shall not seal on the thread, e.g. use of an O-ring seal. The presetting device shall not be able to fall i
46、nto the gas ways of the thermostat. If an O-ring or equivalent gasket provides a seal against the atmosphere, then when the presetting device is completely unscrewed it shall not be able to be pushed out by gas pressure and shall remain tight at the maximum pressure specified in 7.3. If a presetting
47、 device is used for different gas families it shall have a fixed minimum orifice. A cover of any presetting device shall require a tool for removal and replacement and it shall not interfere with the adjustment of the temperature range. 6.3 Materials Shall be according to EN 13611:2007, 6.3. 6.4 Gas
48、 connections 6.4.1 Making connections Shall be according to EN 13611:2007, 6.4.1. BS EN 257:2010EN 257:2010 (E) 9 6.4.2 Connection sizes Shall be according to EN 13611:2007, 6.4.2. 6.4.3 Threads Shall be according to EN 13611:2007, 6.4.3. 6.4.4 Union joints Shall be according to EN 13611:2007, 6.4.4
49、. 6.4.5 Flanges Shall be according to EN 13611:2007, 6.4.5. 6.4.6 Compression fittings Shall be according to EN 13611:2007, 6.4.6. 6.4.7 Nipples for pressure test Shall be according to EN 13611:2007, 6.4.7. 6.4.8 Strainers Shall be according to EN 13611:2007, 6.4.8. 6.4.101 Flow characteristics An adjustable bypass shall be set by means of a variable presetting device or shall be adjusted by means of a fixed presetting device. It shall be possible to gain access to any fixed bypas
