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1、BRITISH STANDARD BS EN 60068-3-4:2002 IEC 60068-3-4:2001 Incorporating Corrigendum No. 1 Environmental testing Part 3-4: Supporting documentation and guidance Damp heat tests The European Standard EN 60068-3-4:2002:2002 has the status of a British Standard ICS 19.040; 19.080 ? Licensed Copy: sheffie
2、ldun sheffieldun, na, Thu Nov 09 08:06:36 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS EN 60068-3-4:2002 This British Standard, having been prepared under the direction of the Electrotechnical Sector Policy and Strategy Committee, was published under the authority of the Standards Policy and Strate
3、gy Committee on 21 March 2002 BSI 19 January 2006 ISBN 0 580 39112 4 National foreword This British Standard is the official English language version of EN 60068-3-4:2002. It is identical with IEC 60068-3-4:2001. It supersedes The UK participation in its preparation was entrusted to Technical Commit
4、tee GEL/10, Environmental conditions, classification and testing, which has the responsibility to: A list of organizations represented on this committee can be obtained on request to its secretary. From 1 January 1997, all IEC publications have the number 60000 added to the old number. For instance,
5、 IEC 27-1 has been renumbered as IEC 60027-1. For a period of time during the change over from one numbering system to the other, publications may contain identifiers from both systems. Cross-references The British Standards which implement these international or European publications may be found i
6、n the BSI Standards Catalogue under the section entitled “International Standards Correspondence Index”, or by using the “Find” facility of the BSI Standards Electronic Catalogue. A British Standard does not purport to include all the necessary provisions of a contract. Users of British Standards ar
7、e responsible for their correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. aid enquirers to understand the text; present to the responsible international/European committee any enquiries on the interpretation, or proposals for change, a
8、nd keep the UK interests informed; monitor related international and European developments and promulgate them in the UK. Summary of pages This document comprises a front cover, an inside front cover, the EN title page, pages 2 to 16, an inside back cover and a back cover. The BSI copyright date dis
9、played in this document indicates when the document was last issued. Amendments issued since publication Amd. No. DateComments 15889 Corrigendum No. 1 19 January 2006Addition of supersession details BS 2011-2.2 C and D:1990 which is withdrawn. Licensed Copy: sheffieldun sheffieldun, na, Thu Nov 09 0
10、8:06:36 GMT+00:00 2006, Uncontrolled Copy, (c) BSI EUROPEAN STANDARDEN 60068-3-4 NORME EUROPENNE EUROPISCHE NORMJanuary 2002 CENELEC European Committee for Electrotechnical Standardization Comit Europen de Normalisation Electrotechnique Europisches Komitee fr Elektrotechnische Normung Central Secret
11、ariat: rue de Stassart 35, B - 1050 Brussels 2002 CENELEC -All rights of exploitation in any form and by any means reserved worldwide for CENELEC members. Ref. No. EN 60068-3-4:2002 E ICS 19.040;29.020Supersedes HD 323.2.28 S1:1988 English version Environmental testing Part 3-4: Supporting documenta
12、tion and guidance Damp heat tests (IEC 60068-3-4:2001) Essais denvironnement Partie 3-4: Documentation daccompagnement et guide Essais de chaleur humide (CEI 60068-3-4:2001) Umweltprfungen Teil 3-4: Untersttzende Dokumentation und Leitfaden Prfungen mit feuchter Wrme (IEC 60068-3-4:2001) This Europe
13、an Standard was approved by CENELEC on 2001-12-04. CENELEC 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
14、concerning such national standards may be obtained on application to the Central Secretariat or to any CENELEC 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 CENELEC member
15、into its own language and notified to the Central Secretariat has the same status as the official versions. CENELEC members are the national electrotechnical committees of Austria, Belgium, Czech Republic, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Malta, Netherl
16、ands, Norway, Portugal, Spain, Sweden, Switzerland and United Kingdom.Inc Licensed Copy: sheffieldun sheffieldun, na, Thu Nov 09 08:06:36 GMT+00:00 2006, Uncontrolled Copy, (c) BSI Foreword The text of document 104/208/FDIS, future edition 1 of IEC 60068-3-4, prepared by IEC TC 104, Environmental co
17、nditions, classification and methods of test, was submitted to the IEC-CENELEC parallel vote and was approved by CENELEC as EN 60068-3-4 on 2001-12-04 This European Standard supersedes HD 323.2.28 S1:1988. The following dates were fixed: latest date by which the EN has to be implemented at national
18、level by publication of an identical national standard or by endorsement(dop) 2002-09-01 latest date by which the national standards conflicting with the EN have to be withdrawn(dow) 2004-12-01 Annexes designated “informative“ are given for information only. In this standard, annex A is informative.
19、 _ Endorsement notice The text of the International Standard IEC 60068-3-4:2001 was approved by CENELEC as a European Standard without any modification. In the official version, for Bibliography, the following notes have to be added for the standards indicated: IEC 60068-1NOTEHarmonized as EN 60068-
20、1:1994 (not modified). IEC 60068-2-1NOTEHarmonized as EN 60068-2-1:1993 (not modified). IEC 60068-2-10NOTEHarmonized as HD 323.2.10 S3:1988 (not modified). IEC 60068-2-14NOTEHarmonized as EN 60068-2-14:1999 (not modified). IEC 60068-2-17NOTEHarmonized as EN 60068-2-17:1994 (not modified). IEC 60068-
21、2-30NOTEHarmonized as EN 60068-2-30:1999 (not modified). IEC 60068-2-38NOTEHarmonized as EN 60068-2-38:1999 (not modified). IEC 60068-2-39NOTEHarmonized as EN 60068-2-39:1999 (not modified). IEC 60068-2-61NOTEHarmonized as EN 60068-2-61:1993 (not modified). IEC 60068-2-66NOTEHarmonized as EN 60068-2
22、-66:1994 (not modified). IEC 60068-2-67NOTEHarmonized as EN 60068-2-67:1996 (not modified). IEC 60068-2-78NOTEHarmonized as EN 60068-2-78:2001 (not modified). _ Page 2 EN 6006834:2002 Licensed Copy: sheffieldun sheffieldun, na, Thu Nov 09 08:06:36 GMT+00:00 2006, Uncontrolled Copy, (c) BSI CONTENTS
23、INTRODUCTION 4 1Scope 5 2Definitions 5 3Procedures for the production and control of humidity. 6 3.1General 6 3.2Injection of water (spraying) 6 3.3Injection of water vapour (steam) 6 3.4Saturation type 6 3.5 Surface evaporation 6 3.6Aqueous solutions. 7 3.7Dehumidification . 7 3.8Control of humidit
24、y 7 4Physical appearance of the effects of humidity . 7 4.1Condensation 7 4.2Adsorption 8 4.3Absorption 8 4.4Diffusion . 8 5Acceleration. 8 5.1General 8 5.2Acceleration factor 9 6Comparison of steady-state and cyclic tests . 9 6.1Test C: Damp heat, steady-state . 9 6.2Test Db: Damp heat, cyclic test
25、. 9 6.3Sequences of tests and composite tests 9 7Influence of test environment on specimens 10 7.1Change of physical characteristics .10 7.2Change of electrical characteristics10 7.3Corrosion.11 Annexe A (informative) Humidity effects diagram 12 Bibliography 16 Figure A.1 Physical processes involved
26、 in humidity testing14 Page 3 EN 6006834:2002 Licensed Copy: sheffieldun sheffieldun, na, Thu Nov 09 08:06:36 GMT+00:00 2006, Uncontrolled Copy, (c) BSI INTRODUCTION Temperature and relative humidity (RH) of the air, in varying combinations, are climatic factors which act upon a product during stora
27、ge, transportation and operation. Meteorological measurements made over many years have shown that a relative humidity 95 % combined with a temperature 30 C does not occur in free air conditions over long periods, except in regions with extreme climates. In dwelling rooms and workshops temperatures
28、of 30 C may occur but in most cases are combined with a lower relative humidity than in the open air. Special conditions exist in certain wet rooms for example, in the chemical industry, metallurgical plants, mines, electroplating plants and laundries, where the temperature can reach 45 C combined w
29、ith a relative humidity up to saturation over long periods. Certain equipment placed under particular conditions may be subjected to relative humidities of more than 95 % at higher temperatures. This may happen when the equipment is placed in enclosures, such as vehicles, tents or aircraft cockpits,
30、 since this can result in intense heating through solar radiation while, because of inadequate ventilation, any humidity that may be developed will be retained permanently within the interior. In rooms having several heat sources, temperatures and relative humidities may vary in different parts of t
31、he room. Atmospheric pollution can intensify the effects of a damp climate on products. Attention is drawn to this fact because of its general importance, although pollutants are not contained in the atmospheres used for damp heat testing. If the effects of pollutants, for example corrosion and moul
32、d growth, are to be investigated, a suitable test from the IEC 60068-2 series should be used. Page 4 EN 6006834:2002 Licensed Copy: sheffieldun sheffieldun, na, Thu Nov 09 08:06:36 GMT+00:00 2006, Uncontrolled Copy, (c) BSI ENVIRONMENTAL TESTING Part 3-4: Supporting documentation and guidance Damp h
33、eat tests 1 Scope This part of IEC 60068 provides the necessary information to assist in preparing relevant specifications, such as standards for components or equipment, in order to select appropriate tests and test severities for specific products and, in some cases, specific types of application.
34、 The object of damp heat tests is to determine the ability of products to withstand the stresses occurring in a high relative humidity environment, with or without condensation, and with special regard to variations of electrical and mechanical characteristics. Damp heat tests may also be utilized t
35、o check the resistance of a specimen to some forms of corrosion attack. 2 Definitions For the purpose of this part of IEC 60068, the following definitions apply. 2.1 condensation precipitation of water vapour on a surface when the surface temperature is lower than the dewpoint temperature of the amb
36、ient air whereby water is transformed from vapour to the liquid state of aggregation 2.2 adsorption adherence of water vapour molecules to a surface when the surface temperature is higher than the dewpoint temperature 2.3 absorption accumulation of water molecules within a material 2.4 diffusion tra
37、nsportation of water molecules through a material, produced by a partial pressure difference NOTE Diffusion results in a balance of partial pressures, whilst flow (such as through leaks, when the dimensions of such leaks are great enough to provide viscous or laminar flow) always finally results in
38、the balance of the total pressures. 2.5 breathing exchange of air between a hollow space and its surroundings, produced by changes of temperature Page 5 EN 6006834:2002 Licensed Copy: sheffieldun sheffieldun, na, Thu Nov 09 08:06:36 GMT+00:00 2006, Uncontrolled Copy, (c) BSI 3 Procedures for the pro
39、duction and control of humidity 3.1 General There are a great number of humidity test chambers available, equipped with different methods of humidity generation and of humidity control. Distilled or deionized water should be used. The water should have a pH value between 6,0 and 7,2 and a minimum re
40、sistivity of 0,05 M?.cm. All internal parts of the chamber should be maintained in a clean condition. In the following subclauses, only the principal methods of generation of humidity are mentioned. 3.2 Injection of water (spraying) Water is atomized to very fine particles or droplets. The spray pro
41、duced in this way moistens the air stream before it enters the working space, the greater part of the droplets evaporating on the way. Small droplets of water may remain in the airflow. Direct water injection into the working space must be avoided. This simple system gives rapid humidification and r
42、equires little maintenance. 3.3 Injection of water vapour (steam) Evaporated water (steam) is blown into the working space of the chamber. This system gives rapid humidification, and is easier maintained (steam valve). However, the resultant heat input may necessitate additional cooling with possibl
43、e dehumidification effects. 3.4 Saturation type Air is blown through a vessel containing water, thus becoming saturated with vapour. At a fixed airflow, the humidity is controlled by changing the water temperature. If an increase of humidification is produced by increasing the water temperature, thi
44、s may cause a temperature rise in the working space and, due to the thermal capacity of the water, the response time may be longer. This may necessitate additional cooling with possible de- humidification effects. If bubbles occur they may produce a small amount of spray when bursting. 3.5 Surface e
45、vaporation The air is humidified by passing it over a large surface area of water. Different methods are used, for example repeated air flow over standing water or water-jet scrubbing over a vertical surface with the air stream in counter current. Page 6 EN 6006834:2002 Licensed Copy: sheffieldun sh
46、effieldun, na, Thu Nov 09 08:06:36 GMT+00:00 2006, Uncontrolled Copy, (c) BSI In this system, the spray is minimized. The humidity is controlled by changing the water temperature. Due to the thermal capacity of the water, the response time may be longer. 3.6 Aqueous solutions Relative humidity is ge
47、nerated over standardized aqueous solutions of salts in small sealed chambers at constant temperature. This system is not appropriate for heat-dissipating specimens or for specimens absorbing large quantities of moisture. Salt particles may be deposited on the surface of the test specimens. In some
48、cases, for example with ammonium salts, these particles may be hazardous to health and may cause stress corrosion in some materials. 3.7 Dehumidification In order to control humidity, various dehumidification methods are used, including cold surfaces, injection of dry air, desiccants etc. 3.8 Contro
49、l of humidity The size of the chamber, the humidifier and the response time of temperature/humidity sensors have important influences on the possible uncertainties of the humidity control system. The chamber performance can degrade, and therefore uncertainty is affected by the quality of maintenance. 4 Physical appearance of the effects of humidity 4.1 Condensation The dewpoint temperature depends on the content of water vapour in the air. A direct relations