1、CEN EN*Eb704 91 E 3404589 0019746 8 0 EUROPEAN STANDARD NORME EUROPENNE EN 26704 : 1991 EUROPISCHE NORM October 1991 UDC 621.646.9.057.6 : 621.186.6 : 6 : 001.4 Descriptois: Valves and fittings, traps : drainage, water vapour, steam, automatic equipment, classification English version Automatic stea
2、m traps - Classification (IS0 6704 : 1980) Purgeurs automatiques de vapeur deau - Classification (IS0 6704 : 1980) (IS0 6704 : 1980) Kondensatableiter - Klassifikation This European Standard was approved by CEN on 30 September 1991 and is identical to the IS0 standard as referred to. CEN members are
3、 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 t
4、he 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 own language and notified to the Central Secretariat has the same sta
5、tus 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, Switzerland and United Kingdom. CEN European Committee for Standardization Co
6、mit Europen de Normalisation Europisches Komitee fr Normung Central Secretariat: rue de Stassart 36, B-1050 Brussels 0 CEN 1991 Copyright reserved to all CEN members Ref. No. EN 26704 : 1991 E CEN ENx26704 73 3404587 0037747 T Page 2 EN 26704 : 1991 I Foreword On the proposal of the %chnical Committ
7、ee CEN/TC 69 Industrial Valves CEN BT decided by resolution C67/1990 to submit the International $tandard IS0 6704 : 1982 : Automatic steam traps - Classification to Formal Vote. This European Standard EN 26704 was approved by CEN on 2 July 1991. According to the Common CENKENELEC Rules, the followi
8、ng countries are bound to implement this European Standard: Austria, Belgium, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Nolway, Portugal, Spain, Sweden, Switzerland and United Kingdom. CEN EN*Zb704 91 = 3404589 00119748 11 E Page 3 EN 26704 : 1991 A
9、utomatic steam traps - Classification 1 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 their obturation device and disregarding their details of conception and construction. Scope and
10、 field of application 2 References IS0 6552, Automatic steam traps - Terminology. IS0 6553, Automatic steam traps - Marking. IS0 6554, Flanged automatic steam traps - Face-to-face dimensions. 3 Definition For this International Standard, the following definition applies : automatic steam trap : Self
11、-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 rafe. 4 Classification The types of traps defined hereunder are classified according to their mode of actuatio
12、n; 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 of actuation of the obturation device, three categorie
13、s of automatic steam traps can be distinguished : - (4.1); mechanical traps, actuated by the level of condensate - thermostatic traps, actuated by the temperature of condensate (4.2); - thermodynamic traps, actuated by fluid dynamics (4.3). CEN ENu26704 93 E 3404589 0039749 3 E Page 4 EN 26704 : 199
14、1 -.I_ Sketch (diagrammatic) 4.1 Mechanical traps (float traps) (actuated by the level of condensate) 4.1.1 Steam trap with closed float Direction of fluid flow 4.1.2 Steam trap with open top float 3 7 5/L 1 Closed float 2 Obturator 3 Lever 4 Seat Direc fluid 1.1.3 Steam trap with open inverted floa
15、t 5 r- * :tio1 flO 1 Float (bucket type) 2 Obturator 3 Lever 4 Siphon 5 Seat n of N I / 4 1 - 7 Direc fluid - 1 Open inverted float 2 Obturator 3 Lever 4 Vent hole 5 Seat :tion of flow Operation The opening or closinc movements of the obturatoi are caused by the variation: of the level of condensate
16、 ir the trap shell. The opening or closing novements of the obturator 3re caused by the variations if the level of condensate in :he float. -he opening or closing novements of the obturator re caused by the variations If the level of condensate in he float. CEN EN*26704 93 = 3404589 0039750 T Sketch
17、 (diagrammatic) 1.2 Thermostatic traps actuated by the temperature of condensate) 1.2.1 Vapour pressure trap 1 Xection of luid flow 1.2.2 Bimetallic or thermoelastic trap 1 7 I Direction of fluid flow 4.2.3 Liquid or solid expansion trap 4 ii 1 Deformable element 2 Obturator 3 Seat 1 Bimetallic elem
18、ent 2 Obturator 3 Seat 1 Expansible element 2 Obturator 3 Seat Direction of fluid flow Page 5 EN 26704 : 1991 Operation The opening or closing movements of the obturator are actuated by imbalances created between the pressure of condensate in the trap and the vapour pressure of the volatile liquid c
19、ontained in a deformable element. 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. The opening or closing movements of the obturator arecaused by the temperature v
20、ariations of the condensate acting on an element with a high thermal expansion coef- f icient . CEN EN*2670Y 91 E 3YOi.1589 OOL975L L E Page 6 EN 26704 : 1991 Sketch (diagrammatic) 4.3 Thermodynamic traps (actuated by fluid dynamics) 4.3.1 Obturator trap 3 2 /- Direction of fluid flow - 4.3.2 Impuls
21、e trap 4 Direction of fluid flow 4.3.3 Labyrinth or orifice trap 1 Obturator 2 Pressure chamber 3 Seat 1 Obturator (piston valve) 2 Pressure chamber 3 Seat 4 Decompression orifice 1 Orifice (one or more) 2 Adjustable obturator (optional) Direction of fluid flow 12 Operation The successive difference
22、s of pressure between the inlet and the pressure chamber cause the opening or closing movements of the obturator. The successive differences of pressure between the inlet and the pressure chamber cause the opening or closing movements of the obturator (piston valve). Fluids pass freely through the orifice. Condensate may eliminate or reduce the flow of steam or non-condens- I ables.
