1、BRITISH STANDARD BS EN 26704:1991 ISO 6704:1982 Classification of Automatic steam traps The European Standard EN26704:1991 has the status of a British StandardBSEN 26704:1991 This British Standard was published under the authorityofthe Standards Boardand comes into effecton 29November1991 BSI 09-199
2、9 The following BSI references relate to the work on this standard: Committee reference PSE/7 Draft for comment 80/71920 DC ISBN 0 580 20219 4 Cooperating organizations The European Committee for Standardization (CEN), under whose supervision this European Standard was prepared, comprises the nation
3、al standards organizations of the following countries. Austria Oesterreichisches Normungsinstitut Belgium Institut belge de normalisation Denmark Dansk Standardiseringsraad Finland Suomen Standardisoimisliito, r.y. France Association franaise de normalisation Germany Deutsches Institut fr Normung e.
4、V. Greece Hellenic Organization for Standardization Iceland Technological Institute of Iceland Ireland National Standards Authority of Ireland Italy Ente Nazionale Italiano di Unificazione Luxembourg Inspection du Travail et des Mines Netherlands Nederlands Normalisatie-instituut Norway Norges Stand
5、ardiseringsforbund Portugal Instituto Portugus da Qualidade Spain Asociacin Espaola de Normalizacin y Certificacin Sweden Standardiseringskommissionen i Sverige Switzerland Association suisse de normalisation United Kingdom British Standards Institution Amendments issued since publication Amd. No. D
6、ate CommentsBSEN 26704:1991 BSI 09-1999 i Contents Page Cooperating organizations Inside front cover National foreword ii Foreword 2 Text of EN 26704 3 National appendix NA (informative) Inside back cover National appendix NB (informative) Inside back coverBSEN 26704:1991 ii BSI 09-1999 National for
7、eword This British Standard has been prepared under the direction of the Piping Systems Components Standards Policy Committee. It is the English language version of EN26704:1991 “Automatic steam traps Classification” published by the European Committee for Standardization (CEN). It supersedes BS6022
8、:1983 which is withdrawn. EN26704:1991 is identical with ISO6704:1982 published by the International Organization for Standardization (ISO). A British Standard does not purport to include all the necessary provisions of a contract. Users of British Standards are responsible for their correct applica
9、tion. Compliance with a British Standard does not of itself confer immunity from legal obligations. Summary of pages This document comprises a front cover, an inside front cover, pages i and ii, theEN title page, pages 2 to 6, an inside back cover and a back cover. This standard has been updated (se
10、e copyright date) and may have had amendments incorporated. This will be indicated in the amendment table on the inside front cover.EUROPEAN STANDARD NORME EUROPENNE EUROPISCHE NORM EN 26704:1991 October 1991 UDC 621.646.9.057.6:621.186.6:6:001.4 Descriptors: Valves and fittings, traps: drainage, wa
11、ter vapour, steam, automatic equipment, classification English version Automatic steam traps Classification (ISO 6704:1980) Purgeurs automatiques de vapeur deau Classification (ISO 6704:1980) Kondensatableiter Klassifikation (ISO6704:1980) This European Standard was approved by CEN on30September1991
12、 and is identical to the ISO standard as referred to. 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 c
13、oncerning such national standards may be obtained on application to the Central Secretariat 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
14、own language and notified to the Central Secretariat has the same status as the official versions. CEN members are the national standards bodies of Austria, Belgium, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerl
15、and and United Kingdom. CEN European Committee for Standardization Comit Europen de Normalisation Europisches Komitee fr Normung Central Secretariat: rue de Stassart 36, B-1050 Brussels CEN 1991 Copyright reserved to all CEN members Ref. No. EN 26704:1991 EEN 26704:1991 BSI 09-1999 2 Foreword On the
16、 proposal of the Technical Committee CEN/TC 69 “Industrial Valves” CEN BT decided by resolution C67/1990 to submit the International Standard ISO6704:1952, Automatic steam traps Classification to Formal Vote. This European Standard EN26704 was approved by CEN on2July1991. According to the Common CEN
17、/CENELEC Rules, the following countries are bound to implement this European Standard: Austria, Belgium, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and United Kingdom. Contents Page Foreword 2 1 Scope and
18、field of application 3 2 References 3 3 Definition 3 4 Classification 3EN 26704:1991 BSI 09-1999 3 1 Scope and field of application The purpose of this International Standard is to establish a simple classification of the main types of automatic steam traps according to the mode of actuation of thei
19、r obturation device and disregarding their details of conception and construction. 2 References ISO 6552, Automatic steam traps Terminology. ISO 6553, Automatic steam traps Marking. ISO 6554, Flanged automatic steam traps Face-to-face dimensions. 3 Definition For this International Standard, the fol
20、lowing definition applies: 3.1 automatic steam trap self-contained valve which automatically drains the condensate from a steam-containing enclosure whilst remaining tight to live steam or, if necessary, allowing steam to flow at a predetermined rate 4 Classification The types of traps defined hereu
21、nder are classified according to their mode of actuation; other traps, combining these different types (or of a new design) may be developed, but these traps shall not be regarded as a characteristic type of automatic steam traps in the sense of this International Standard. If one considers the mode
22、 of actuation of the obturation device, three categories of automatic steam traps can be distinguished: mechanical traps, actuated by the level of condensate (4.1); thermostatic traps, actuated by the temperature of condensate (4.2); thermodynamic traps, actuated by fluid dynamics (4.3).EN 26704:199
23、1 4 BSI 09-1999 Sketch (diagrammatic) Operation 4.1 Mechanical traps (float traps) (actuated by the level of condensate) 4.1.1 Steam trap with closed float The opening or closing movements of the obturator are caused by the variations of the level of condensate in the trap shell. 4.1.2 Steam trap wi
24、th open top float The opening or closing movements of the obturator are caused by the variations of the level of condensate in the float. 4.1.3 Steam trap with open inverted float The opening or closing movements of the obturator are caused by the variations of the level of condensate in the float.E
25、N 26704:1991 BSI 09-1999 5 Sketch (diagrammatic) Operation 4.2 Thermostatic traps (actuated by the temperature of condensate) 4.2.1 Vapour pressure trap The opening or closing movements of the obturator are actuated by imbalances created between the pressure of condensate in the trap and the vapour
26、pressure of the volatile liquid contained in a deformable element. 4.2.2 Bimetallic or thermoelastic trap The temperature changes of the incoming condensate cause the deformation of the bimetallic or thermoelastic element, and consequently the opening and closing movements of the obturator. 4.2.3 Li
27、quid or solid expansion trap The opening or closing movements of the obturator are caused by the temperature variations of the condensate acting on an element with a high thermal expansion coefficient.EN 26704:1991 6 BSI 09-1999 Sketch (diagrammatic) Operation 4.3 Thermodynamic traps (actuated by fl
28、uid dynamics) 4.3.1 Obturator trap The successive differences of pressure between the inlet and the pressure chamber cause the opening or closing movements of the obturator. 4.3.2 Impulse trap The successive differences of pressure between the inlet and the pressure chamber cause the opening or clos
29、ing movements of the obturator (piston valve). 4.3.3 Labyrinth or orifice trap Fluids pass freely through the orifice. Condensate may eliminate or reduce the flow of steam or non-condensables.BSEN 26704:1991 BSI 09-1999 National appendix NA (informative) The United Kingdom participation in the prepa
30、ration of this European Standard was entrusted by the Piping Systems Components Standards Policy Committee (PSE/-) to Technical Committee PSE/7, upon which the following bodies were represented: Amalgamated Engineering Union Association of Bronze and Brass Founders Association of Building Component
31、Manufacturers British Chemical Engineering Contractors Association British Foundry Association British Gas plc British Maritime Technology British Plumbing Fittings Manufacturers Association British Valve and Actuator Manufacturers Association Chartered Institution of Building Services Engineers Cop
32、per Development Association Department of the Environment (Property Services Agency) Electricity Industry in United Kingdom Energy Industries Council Engineering Equipment and Materials Users Association Fire Extinguishing Trades Association GAMBICA (BEAMA Ltd.) Health and Safety Executive Institute
33、 of British Foundrymen Institution of Chemical Engineers Institution of Mechanical Engineers Institution of Water and Environmental Management Liquefied Petroleum Gas Industry Technical Association (UK) Pipeline Industries Guild Society of British Gas Industries Society of British Water Industries W
34、ater Companies Association Water Services Association of England and Wales West Midlands CBI National appendix NB (informative) The British Standards corresponding to the International Standards referred to in the text are as follows: International Standard British Standard ISO 6552:1980 BS 6023:198
35、1 Glossary of technical terms for automatic steam traps (Identical) ISO 6553:1980 BS EN 26553:1991 Specification for marking of automatic steam traps (Identical) ISO 6554:1980 BS EN 26554:1991 Specification for face-to-face dimensions for flanged automatic steam traps (Identical)BS EN 26704:1991 ISO
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