00257483 PDF BRITISH STANDARD BS EN 27841 1991 ISO 7841 1988 Methods for Determination of steam loss of automatic steam traps The European Standard EN 27841 1991 has the status of a British Standard B[.]
BRITISH STANDARD Methods for Determination of steam loss of automatic steam traps The European Standard EN 27841:1991 has the status of a British Standard BS EN 27841:1991 ISO 7841:1988 BS EN 27841:1991 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 This British Standard was published under the authority of the Standards Board and comes into effect on 29 November 1991 © BSI 11-1999 The following BSI references relate to the work on this standard: Committee reference PSE/7 Draft for comment 85/73145 DC ISBN 580 20221 Austria Oesterreichisches Normungsinstitut Belgium Institut belge de normalisation Denmark Dansk Standardiseringsraad Finland Suomen Standardisoimisliito, r.y France Association franỗaise de normalisation Germany Deutsches Institut fỹr 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 Espola 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 27841:1991 Contents Cooperating organizations National foreword Foreword Text of EN 27841 National appendix NA (informative) National appendix NB (informative) © BSI 11-1999 Page Inside front cover ii Inside back cover Inside back cover i BS EN 27841:1991 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 27841:1991 “Automatic steam traps — Determination of steam loss — Test methods” published by the European Committee for Standardization (CEN) It supersedes BS 6027:1990 which is withdrawn EN 27841:1991 is identical with ISO 7841:1988 published by the International Organization for Standardization (ISO) A British Standard does not purport to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 to 14, 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 ii © BSI 11-1999 EUROPEAN STANDARD EN 27841:1991 NORME EUROPÉENNE October 1991 EUROPÄISCHE NORM UDC 621.646.9.057:621.186.1:620.1 Descriptors: Industrial valves, traps: drainage, water vapour, steam, tests, measurements, head losses English version Automatic steam traps — Determination of steam loss — Test methods (ISO 7841:1988) Purgeurs automatiques de vapeur d’ eau — Détermination de la perte de vapeur — Méthodes d’ essai (ISO 7841:1988) Kondensatableiter — Bestimmung des Dampfverlustes — Prüfverfahren (ISO 7841:1988) 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 27841:1991 E EN 27841:1991 Foreword On the proposal of the Technical Committee CEN/TC 69 “Industrial Valves” CEN BT has decided by resolution C67/1990 to submit the International Standard ISO 7841:1988: Automatic steam traps — Determination of steam loss — Test methods to Formal Vote This European Standard was adopted by CEN on August 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 Foreword Scope and field of application References Test arrangements Test method A Test method B Bibliography Figure — Test arrangement for steam loss tests with test method A Figure — Test arrangement for steam loss tests with test method B Page 3 3 13 Endorsement The text of the International Standard ISO 7481:1988 was approved by CEN as a European Standard without any modifications © BSI 11-1999 EN 27841:1991 Scope and field of application This International Standard specifies two test methods to determine the steam loss of automatic steam traps to ISO 6552 The object of these tests is to determine the amount of live steam, if any, that is lost through the steam trap They are, therefore, tests to evaluate the ability of the traps to shut against steam during successive operations There is no measurement of the total heat energy lost by the trap Such total heat loss would include radiation and convection components which can be established separately References ISO 651, Solid-stem calorimeter thermometers ISO 652, Enclosed-scale calorimeter thermometers ISO 653, Long solid-stem thermometers for precision use ISO 4185, Measurement of liquid flow in closed conduits — Weighing method ISO 6552, Automatic steam traps — Definition of technical terms Test arrangements The test arrangements for steam loss determination are shown in Figure and Figure The minimum water capacity of the calorimeter tank (see Figure 1) shall be 0,02 m3 It is most important that the condensate drainage device be fully capable of maintaining a dry line to the heat exchanger The test device shall be located sufficiently below the heat exchanger to prevent condensate backing up into the heat exchanger, should the test device only operate infrequently All piping and equipment (including the heat exchanger) shall be insulated to a value of to reduce thermal losses to a minimum The instruments used for the measurements shall comply with International Standards, if such standards exist, e.g — ISO 651, ISO 652, ISO 653 for temperature measurements; — ISO 4185 for flow measurements The condensate removal device shall not be modified in any way from its commercial form Test method A © BSI 11-1999 EN 27841:1991 © BSI 11-1999 1) Operating at steam temperature Figure — Test arrangement for steam loss tests with test method A EN 27841:1991 The test may be carried out at a pressure corresponding to the maximum working pressure of the trap, the test pressure not exceeding 32 bar 1) with saturated steam (238 °C) Load testing shall be carried out at % of the maximum capacity of the trap at the corresponding test pressure with a minimum of kg/h 4.1 Procedure 4.1.1 No-load condition Start with all valves closed and tanks empty 4.1.1.1 Open valves 1, and to permit the drain and test devices to operate at test pressure ps 4.1.1.2 During warm-up, weigh and record the mass of the empty calorimeter tank mt, and record the steam pressure ps and steam temperature Ús 4.1.1.3 Fill the calorimeter tank with sufficient water (about half-full) to result in a test run of practical duration The initial water temperature Ú1 should be at least °C below ambient temperature Úa Record the water temperature Ú1 and mass of water plus tank m1 4.1.1.4 When thermal equilibrium is reached, simultaneously and rapidly close valve 3, open valve 4, and start the timing interval The use of a three-way valve is recommended to facilitate rapid closing and opening 4.1.1.5 Stir the water in the tank as necessary to ensure a uniform water temperature 4.1.1.6 When the temperature of the water in the tank is as many degrees above ambient as the initial temperature was below, rapidly close valve and open valve simultaneously, record the elapsed time, the final water temperature Ú2 and the mass of water plus tank m2 4.1.1.7 Before the measurement, trial runs should be carried out to ensure that the test conditions have stabilized and that the pressure, temperature, initial amount of water in the calorimeter tank and load conditions are those required When testing condensate removal devices, an error calculation is made from three consecutive tests to determine the accuracy of the test result The error calculation is based on the instrumentation used and described in this International Standard; or the average result from three consecutive tests shall agree within 10 % or 500 g/h, whichever is the greater If this cannot be obtained, check the system for integrity and increase the calorimeter tank capacity 4.1.2 Load condition Start with all valves closed and both tanks empty 4.1.2.1 Open valves 1, and to permit the drain and test devices to operate at test pressure ps 4.1.2.2 During warm-up, weigh and record the mass of the empty calorimeter tank mt, and record the steam pressure ps and steam temperature Ús 4.1.2.3 Open valves and to allow a flow of cooling water through the heat exchanger, to create the desired condensate load on the test device After the system has come to equilibrium, this load can be determined by closing valve and opening valve 7, to permit a known amount of water to be collected in a given time Record the temperature of water entering and leaving the heat exchanger, ÚE and ÚL, the initial and final mass of exchanger water plus tank, m3 and m4, and the time %t, in seconds, of run on the Data Sheet in 4.3 The approximate condensate load, in kilograms per hour, on the trap may then be calculated using the formula where hfgs is the specific enthalpy of the evaporation at steam inlet conditions, in joules per kilogram 4.1.2.4 If the load on the trap as determined in 4.1.2.3 is as desired, proceed to 4.1.2.5 If it is not as desired, adjust valve accordingly and repeat the procedure in 4.1.2.3 until the desired load is obtained 1) bar = 105 Pa © BSI 11-1999 EN 27841:1991 4.1.2.5 Fill the calorimeter tank with sufficient water (about half-full) to result in a test run of practical duration The initial water temperature Ú1 should be at least °C below ambient temperature Úa Record the water temperature Ú1 and mass of water plus tank m1 4.1.2.6 When thermal equilibrium is reached, simultaneously and rapidly close valve 3, and open valve 4, and start the timing interval The use of a three-way valve is recommended to facilitate rapid closing and opening 4.1.2.7 Stir the water in the calorimeter tank as necessary to ensure a uniform water temperature 4.1.2.8 When the temperature of the water in the calorimeter tank is as many degrees above ambient as the initial temperature was below, rapidly close valve and open valve simultaneously, record the elapsed time, the final water temperature Ú2 and the mass of water plus tank m2 4.1.2.9 Before the measurement, trial runs should be carried out to ensure that the test conditions have stabilized and that the pressure, temperature, initial amount of water in the calorimeter tank and load conditions are those required When testing condensate removal devices, an error calculation is made from three consecutive tests to determine the accuracy of the test result The error calculation is based on the instrumentation used and described in this International Standard; or the average result from three consecutive tests shall agree within 10 % or 500 g/h, whichever is the greater If this cannot be obtained, check the system for integrity and increase the calorimeter tank capacity 4.2 Expression of results 4.2.1 Correction of measured variables The values of observed variables shall be corrected in accordance with instrument calibrations and, if necessary, converted to the proper units required for calculations 4.2.2 Use of formula symbols The symbols used in this International Standard are the ones normally associated with engineering practice in this field In a few cases, the same symbol has different meanings in different parts of this International Standard according to its application In order to avoid confusion, each formula has been provided with its own list of definitions of symbols and units 4.2.3 Computation formula where qms is the steam loss, in kilograms per hour; mi is the initial mass of water in the calorimeter, in kilograms; mf is the final mass of water and condensate in the calorimeter, in kilograms; m1 is the mass of calorimeter plus water, at the start, in kilograms; m2 is the mass of calorimeter plus water, at the finish, in kilograms; mt is the mass of calorimeter tank, in kilograms; hf1 is the initial specific enthalpy of water in the calorimeter, in joules per kilogram; hf2 is the final specific enthalpy of the condensate and water in the calorimeter, in joules per kilogram; hfs is the specific enthalpy of the liquid at steam inlet conditions, in joules per kilogram; hfgs is the specific enthalpy of the evaporation at steam inlet conditions, in joules per kilogram; cp is the specific heat of the calorimeter material, in joules per kilogram kelvin; Ú1 is the initial water temperature in the calorimeter tank, in degrees Celsius; Ú2 is the water temperature in the calorimeter tank, in degrees Celsius; %t is the time interval, in seconds © BSI 11-1999 EN 27841:1991 4.3 Data sheet © BSI 11-1999 EN 27841:1991 Test method B © BSI 11-1999 © BSI 11-1999 2) The separating tank should be kept hot by a heated jacket or an insulating system Operating at steam temperature Figure — Test arrangement for stream loss tests with test method B EN 27841:1991 1) EN 27841:1991 The test may be carried out at a pressure corresponding to the maximum working pressure of the trap, the test pressure not exceeding 32 bar with saturated steam (238 °C) Load testing shall be carried out at % of the maximum capacity of the trap at the corresponding test pressure with a minimum of kg/h 5.1 Procedure 5.1.1 No-load condition Start with all valves closed and tanks empty 5.1.1.1 Open valves 1, and to permit the drain and test devices to operate at test pressure ps 5.1.1.2 Fill the condensing tank with approximately 20 kg of cold water 5.1.1.3 Open valve and close valve to permit the separating tank and associated pipework to warm up Close valve and open valves and Allow any condensate which has collected to drain out Measure and record the mass of the condensing tank and its water 5.1.1.4 Simultaneously and rapidly close valves and 8, open valve 4, and start the time interval 5.1.1.5 During the test period, record the steam pressure ps, the test device inlet temperature Ús, and the outlet temperature Úo 5.1.1.6 At the end of the set test time, simultaneously and rapidly close valve and open valve 5.1.1.7 Record the mass of the empty measuring vessel Open valve and drain condensate into the measuring vessel and reweigh Record the mass Measure and record the final mass of the condensing tank and its water 5.1.1.8 Calculate the steam loss in accordance with 5.2 5.1.1.9 When testing condensate removal devices, an error calculation is made from three consecutive tests to determine the accuracy of the test result The error calculation is based upon the instrumentation used and described in this International Standard; or the results from three consecutive tests shall agree within 10 % or 500 g/h, whichever is the greater If this cannot be obtained, check the system for integrity 5.1.2 Load condition Start with all valves closed and tanks empty 5.1.2.1 Open valves 1, and to permit the drain and test devices to operate at test pressure ps 5.1.2.2 Open valves and to allow a flow of cooling water through the heat exchanger to create the desired condensate load on the test device After the system has come to equilibrium, this load can be determined by closing valve and opening valve to permit a known amount of water to be collected in a given time Record the temperatures of water entering and leaving the heat exchanger, ÚE and ÚL, the initial and final weights of exchanger water plus tank, m5 and m6, and the time %t, in seconds, of run on the Data Sheet in 5.3 The approximate condensate load, in kilograms per hour, on the trap may then be calculated using the formula: where hfgs is the specific enthalpy of the evaporation at steam inlet conditions, in joules per kilogram 5.1.2.3 If the load on the trap as determined in 5.1.2.2 is as desired, proceed to 5.1.2.4 If it is not as desired, adjust valve accordingly and repeat the procedure in 5.1.2.2, until the desired condensate load is obtained 5.1.2.4 Fill the condensing tank with approximately 20 kg of cold water NOTE After completing 5.1.2.4, the procedures described in 5.1.2.5 and 5.1.2.6 should be executed as quickly as possible 5.1.2.5 Open valve and close valve to permit the separating tank and associated pipework to warm up Close valve and open valves and Allow any condensate which has collected to drain out Measure and record the mass of the condensing tank and its water 5.1.2.6 Simultaneously and rapidly close valves and 8, open valve 4, and start the time interval 5.1.2.7 During the test period, record the steam pressure ps, the test device inlet temperature Ús and the outlet temperature Úo 10 © BSI 11-1999 EN 27841:1991 5.1.2.8 At the end of the set test time, simultaneously and rapidly close valve and open valve 5.1.2.9 Record the mass of the empty measuring vessel Open valve and drain condensate into the measuring vessel and reweigh Record the mass Measure and record the final mass of the condensing tank and its water 5.1.2.10 Calculate the steam loss in accordance with 5.2 5.1.2.11 When testing condensate removal devices, an error calculation is made from three consecutive tests to determine the accuracy of the test result The error calculation is based upon the instrumentation used and described in this International Standard; or the results from three consecutive tests shall agree within 10 % or 500 g/h, whichever is the greater If this cannot be obtained, check the system for integrity 5.2 Expression of results 5.2.1 Correction of measured variables The values of observed variables shall be corrected in accordance with instrument calibrations and, if necessary, converted to the proper units required for calculations 5.2.2 Use of formula symbols The symbols used in this International Standard are the ones normally associated with engineering practice in this field In a few cases, the same symbol has different meanings in different parts of this International Standard according to its application In order to avoid confusion, each formula has been provided with its own list of definitions of symbols and units 5.2.3 Computation formula where qms is the steam loss, in kilograms per hour; mst is the mass of steam collected in the condensing tank, in kilograms; mc is the mass of condensate collected in the separating tank, in kilograms; hfs is the specific enthalpy of the liquid at the trap inlet temperature, in joules per kilogram; hfo is the specific enthalpy of the liquid at the trap outlet temperature, in joules per kilogram; hgo is the specific enthalpy of the saturated steam at the trap outlet temperature, in joules per kilogram; hgs is the specific enthalpy of the saturated steam at the trap inlet temperature, in joules per kilogram; %t is the time interval, in seconds If the value of qms, in kilograms per hour, exceeds the following value, a calibration of the separating efficiency of the separator shall be made and applied to correct the readings measured where D is the inside diameter of the separating tank, in metres; v1 is the specific volume of saturated steam in the separating tank, in cubic metres per kilogram © BSI 11-1999 11 EN 27841:1991 5.3 Data sheet 12 © BSI 11-1999 EN 27841:1991 Bibliography ISO 6704, Automatic steam traps — Classification ISO 6948, Automatic steam traps — Production and performance characteristic tests © BSI 11-1999 13 14 blank BS EN 27841:1991 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 653:1980 BS 5074:1974 Specification for short and long solid-stem thermometers for precision use (Technically equivalent) ISO 4185:1980 BS 6199 Measurement of liquid flow in closed conduits using weighing and volumetric methods Part 1:1981 Weighing method (Identical) ISO 6552:1980 BS 6023:1981 Glossary of technical terms for automatic steam traps (Identical) © BSI 11-1999 BS EN 27841:1991 ISO 7841:1988 BSI — British Standards Institution BSI is the independent national body responsible for preparing British Standards It presents the UK view on standards in Europe and at the international level It is incorporated by Royal Charter Revisions British Standards are updated by amendment or revision Users of British Standards should make sure that they possess the latest amendments or editions It is the constant aim of BSI to improve the quality of our products and services We would be grateful if anyone finding an inaccuracy or ambiguity while using this British Standard would inform the Secretary of the technical committee responsible, the identity of which can be found on the inside front cover Tel: 020 8996 9000 Fax: 020 8996 7400 BSI offers members an individual updating service called PLUS which ensures that subscribers automatically receive the latest editions of standards Buying standards Orders for all BSI, international and foreign standards publications should be addressed to Customer Services Tel: 020 8996 9001 Fax: 020 8996 7001 In response to orders for international standards, it is BSI policy to supply the BSI implementation of those that have been published as British Standards, unless otherwise requested Information on standards BSI provides a wide range of information on national, European and international standards through its Library and its Technical Help to Exporters Service Various BSI electronic information services are also available which give details on all its products and services Contact the Information Centre Tel: 020 8996 7111 Fax: 020 8996 7048 Subscribing members of BSI are kept up to date with standards developments and receive substantial discounts on the purchase price of standards For details of these and other benefits contact Membership Administration Tel: 020 8996 7002 Fax: 020 8996 7001 Copyright Copyright subsists in all BSI publications BSI also holds the copyright, in the UK, of the publications of the international standardization bodies Except as permitted under the Copyright, Designs and Patents Act 1988 no extract may be reproduced, stored in a retrieval system or transmitted in any form or by any means – electronic, photocopying, recording or otherwise – without prior written permission from BSI This does not preclude the free use, in the course of implementing the standard, of necessary details such as symbols, and size, type or grade designations If these details are to be used for any other purpose than implementation then the prior written permission of BSI must be obtained BSI 389 Chiswick High Road London W4 4AL If permission is granted, the terms may include royalty payments or a licensing agreement Details and advice can be obtained from the Copyright Manager Tel: 020 8996 7070