Bsi bs en 26704 1991 (1999) iso 6704 1982

00257468 PDF BRITISH STANDARD BS EN 26704 1991 ISO 6704 1982 Classification of Automatic steam traps The European Standard EN 26704 1991 has the status of a British Standard BS EN 26704 1991 This Brit[.]

BRITISH STANDARD BS EN

26704:1991 ISO 6704:1982

Classification of

Automatic steam traps

The European Standard EN 26704:1991 has the status of a

British Standard

This British Standard was

published under the

authority of the Standards

Board and comes

into effect on

29 November 1991

© BSI 09-1999

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 national standards organizations of the following countries

Austria Oesterreichisches Normungsinstitut Belgium Institut belge de normalisation Denmark Dansk Standardiseringsraad Finland Suomen Standardisoimisliito, r.y

France Association française de normalisation Germany Deutsches Institut für Normung e.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 Standardiseringsforbund Portugal Instituto Portuguès da Qualidade Spain Asociación Española de Normalización y Certificación Sweden Standardiseringskommissionen i Sverige

Switzerland Association suisse de normalisation United Kingdom British Standards Institution

Amendments issued since publication

Amd No Date Comments

BS EN 26704:1991

Contents

Page Cooperating organizations Inside front cover

National appendix NA (informative) Inside back cover National appendix NB (informative) Inside back cover

ii © BSI 09-1999

National foreword

This British Standard has been prepared under the direction of the Piping Systems Components Standards Policy Committee It is the English language

version of EN 26704:1991 “Automatic steam traps — Classification” published by

the European Committee for Standardization (CEN) It supersedes BS 6022:1983 which is withdrawn EN 26704:1991 is identical with ISO 6704:1982 published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 application

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, the EN title page, pages 2 to 6, an inside back cover and a back cover

This standard has been updated (see copyright date) and may have had amendments incorporated This will be indicated in the amendment table on the inside front cover

EUROPEAN STANDARD

NORME EUROPÉENNE

EUROPÄISCHE NORM

EN 26704:1991

October 1991

UDC 621.646.9.057.6:621.186.6:6:001.4

Descriptors: Valves and fittings, traps: drainage, water vapour, steam, automatic equipment, classification

English version

Automatic steam traps — Classification

(ISO 6704:1980)

Purgeurs automatiques de vapeur d’eau —

Classification

(ISO 6704:1980)

Kondensatableiter — Klassifikation (ISO 6704:1980)

This European Standard was approved by CEN on 30 September 1991 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 concerning 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 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, Switzerland and

United Kingdom

CEN

European Committee for Standardization Comité Européen de Normalisation Europäisches Komitee für Normung

Central Secretariat: rue de Stassart 36, B-1050 Brussels

© CEN 1991 Copyright reserved to all CEN members

Ref No EN 26704:1991 E

© BSI 09-1999

2

Foreword

On the proposal of the Technical Committee

CEN/TC 69 “Industrial Valves” CEN BT decided by

resolution C67/1990 to submit the International

Standard

ISO 6704:1952, Automatic steam traps —

Classification to Formal Vote.

This European Standard EN 26704 was approved

by CEN on 2 July 1991

According to the Common CEN/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

1 Scope and field of application 3

EN 26704:1991

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 their 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 following

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 hereunder 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 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).

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 with 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

EN 26704:1991

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 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 Liquid 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

6 © BSI 09-1999

Sketch (diagrammatic) Operation

4.3 Thermodynamic traps

(actuated by fluid 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 closing 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

BS EN 26704:1991

© BSI 09-1999

National appendix NA (informative)

The United Kingdom participation in the preparation 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 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

Copper 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 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

Water 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 6023:1981 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)

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