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1、BRITISH STANDARD BS EN ISO 7235:2003 Incorporating Corrigendum No. 1 Acoustics Laboratory measurement procedures for ducted silencers and air-terminal units Insertion loss, flow noise and total pressure loss The European Standard EN ISO 7235:2003 has the status of a British Standard ICS 91.120.20 ?
2、Licensed Copy: sheffieldun sheffieldun, na, Mon Nov 20 03:08:57 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS EN ISO 7235:2003 This British Standard was published under the authority of the Standards Policy and Strategy Committee on 8 September 2003 BSI 23 October 2003 ISBN 0 580 42578 9 National fo
3、reword This British Standard is the official English language version of EN ISO 7235:2003. It is identical with ISO 7235:2003. It supersedes BS EN ISO 7235:1996 and BS 4718:1971 which are withdrawn. The UK participation in its preparation was entrusted by Technical Committee EH/1, Acoustics, to Subc
4、ommittee EH/1/4, Machinery noise, which has the responsibility to: A list of organizations represented on this subcommittee can be obtained on request to its secretary. Cross-references The British Standards which implement international or European publications referred to in this document may be f
5、ound in the BSI Catalogue under the section entitled “International Standards Correspondence Index”, or by using the “Search” facility of the BSI Electronic Catalogue or of British Standards Online. This publication does not purport to include all the necessary provisions of a contract. Users are re
6、sponsible for its 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, and kee
7、p 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 ISO title page, the EN ISO foreword page, the ISO title page, pages ii to v, a blank page, pages 1
8、 to 49, the Annex ZA page, the Annex ZB page and a back cover. The BSI copyright notice displayed in this document indicates when the document was last issued. Amendments issued since publication Amd. No. DateComments 14785 Corrigendum No. 1 23 October 2003Correction to EN ISO foreword page, incorpo
9、rating the Annex ZA and Annex ZB pages Licensed Copy: sheffieldun sheffieldun, na, Mon Nov 20 03:08:57 GMT+00:00 2006, Uncontrolled Copy, (c) BSI EUROPEAN STANDARD NORME EUROPENNE EUROPISCHE NORM EN ISO 7235 August 2003 ICS 91.120.20Supersedes EN ISO 7235:1995 English version Acoustics - Laboratory
10、measurement procedures for ducted silencers and air-terminal units - Insertion loss, flow noise and total pressure loss (ISO 7235:2003) Acoustique - Modes opratoires de mesure en laboratoire pour silencieux en conduit et units terminales - Perte dinsertion, bruit dcoulement et perte de pression tota
11、le (ISO 7235:2003) Akustik - Labormessungen an Schalldmpfern in Kanlen - Einfgungsdmpfung, Strmungsgerusch und Gesamtdruckverlust (ISO 7235:2003) This European Standard was approved by CEN on 20 June 2003. CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the
12、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 Management Centre or to any CEN member. This European Standard exists in thr
13、ee 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 Management Centre has the same status as the official versions. CEN members are the national standards bodies of Aust
14、ria, Belgium, Czech Republic, Denmark, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Luxembourg, Malta, Netherlands, Norway, Portugal, Slovakia, Spain, Sweden, Switzerland and United Kingdom. EUROPEAN COMMITTEE FOR STANDARDIZATION COMIT EUROPEN DE NORMALISATION EUROPISCHES KOMI
15、TEE FR NORMUNG Management Centre: rue de Stassart, 36 B-1050 Brussels 2003 CENAll rights of exploitation in any form and by any means reserved worldwide for CEN national Members. Ref. No. EN ISO 7235:2003 E Licensed Copy: sheffieldun sheffieldun, na, Mon Nov 20 03:08:57 GMT+00:00 2006, Uncontrolled
16、Copy, (c) BSI CORRECTED 2003-09-24 Foreword This document (EN ISO 7235:2003) has been prepared by Technical Committee ISO/TC 43 “Acoustics“ in collaboration with Technical Committee CEN/TC 211 “Acoustics“, the secretariat of which is held by DS. This European Standard shall be given the status of a
17、national standard, either by publication of an identical text or by endorsement, at the latest by February 2004, and conflicting national standards shall be withdrawn at the latest by February 2004. This document supersedes EN ISO 7235:1995. This document has been prepared under a mandate given to C
18、EN by the European Commission and the European Free Trade Association, and supports essential requirements of EU Directive(s). For relationship with EU Directive(s), see informative annex ZB, which is an integral part of this document. According to the CEN/CENELEC Internal Regulations, the national
19、standards organizations of the following countries are bound to implement this European Standard: Austria, Belgium, Czech Republic, Denmark, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Luxembourg, Malta, Netherlands, Norway, Portugal, Slovakia, Spain, Sweden, Switzerland and
20、the United Kingdom. Endorsement notice The text of ISO 7235:2003 has been approved by CEN as EN ISO 7235:2003 without any modifications. NOTE Normative references to International Standards are listed in Annex ZA (normative). EN ISO 7235:2003 Licensed Copy: sheffieldun sheffieldun, na, Mon Nov 20 03
21、:08:57 GMT+00:00 2006, Uncontrolled Copy, (c) BSI Reference number ISO 7235:2003(E) INTERNATIONAL STANDARD ISO 7235 Second edition 2003-08-01 Acoustics Laboratory measurement procedures for ducted silencers and air-terminal units Insertion loss, flow noise and total pressure loss Acoustique Modes op
22、ratoires de mesure en laboratoire pour silencieux en conduit et units terminales Perte dinsertion, bruit dcoulement et perte de pression totale EN ISO 7235:2003 Licensed Copy: sheffieldun sheffieldun, na, Mon Nov 20 03:08:57 GMT+00:00 2006, Uncontrolled Copy, (c) BSI ii EN ISO 7235:2003 Licensed Cop
23、y: sheffieldun sheffieldun, na, Mon Nov 20 03:08:57 GMT+00:00 2006, Uncontrolled Copy, (c) BSI IS:5327 O3002(E) iii Contents Page Forewordiv Introduction v 1 Scope1 2 Normative references .1 3 Terms and definitions.2 4 Symbols .7 5 Test facilities and requirements for instrumentation9 5.1 Purpose an
24、d types of test facilities.9 5.2 Equipment for acoustic testing of silencers9 5.3 Equipment for acoustic testing of air-terminal units 15 5.4 Equipment for flow testing.16 5.5 Equipment for dynamic testing .21 6 Test procedures 22 6.1 General.22 6.2 Insertion loss.22 6.3 Transmission loss.24 6.4 Sou
25、nd power level of the flow noise (or regenerated sound)24 6.5 Volume flow rate and pressure loss coefficient 25 7 Information to be recorded 29 7.1 Description of the test object 29 7.2 Instrumentation.29 7.3 Sound-source equipment.30 7.4 Test, substitution and transmission ducts.30 7.5 Transitions.
26、30 7.6 Anechoic termination .30 7.7 Reverberation room30 7.8 Acoustical test results30 7.9 Measurement uncertainty.31 8 Information to be reported.31 Annex A (normative) Design of the sound field excitation equipment and qualification tests 32 Annex B (normative) Transmission element34 Annex C (norm
27、ative) Duct walls and limiting insertion loss37 Annex D (normative) Conversion of one-third-octave-band attenuation values to octave-band attenuation values.40 Annex E (normative) Measurements on large parallel-baffle silencers 41 Annex F (normative) Test of longitudinal attenuation 43 Annex G (info
28、rmative) Anechoic terminations.44 Annex H (informative) Examples of measurement arrangements.46 Bibliography .48 EN ISO 7235:2003 Licensed Copy: sheffieldun sheffieldun, na, Mon Nov 20 03:08:57 GMT+00:00 2006, Uncontrolled Copy, (c) BSI IS:5327 O3002(E) iv Foreword ISO (the International Organizatio
29、n for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of preparing International Standards is normally carried out through ISO technical committees. Each member body interested in a subject for which a technical committee has been established has
30、 the right to be represented on that committee. International organizations, governmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization. Inter
31、national Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2. The main task of technical committees is to prepare International Standards. Draft International Standards adopted by the technical committees are circulated to the member bodies for voting. Publicat
32、ion as an International Standard requires approval by at least 75 % of the member bodies casting a vote. Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. ISO shall not be held responsible for identifying any or all such patent righ
33、ts. ISO 7235 was prepared by Technical Committee ISO/TC 43, Acoustics, Subcommittee SC 1, Noise. This second edition cancels and replaces the first edition (ISO 7235:1991), which has been technically revised. EN ISO 7235:2003 Licensed Copy: sheffieldun sheffieldun, na, Mon Nov 20 03:08:57 GMT+00:00
34、2006, Uncontrolled Copy, (c) BSI IS:5327 O3002(E) v Introduction This International Standard specifies the substitution method for determining the insertion loss of ducted silencers and a method for determining the transmission loss of air-terminal units. In the substitution method, the sound pressu
35、re level of the transmitted wave is first determined for the test object and then when the test object has been replaced by the substitution duct. The sound pressure level of the transmitted wave can be measured in a reverberation room, in a test duct after the silencer, or in an essentially free fi
36、eld. The methods are listed in order of preference. The acoustic performance of silencers depends on the modal composition of the sound field at the inlet and on reflections at the outlet side, on flanking transmission and on level differences between signals and flow noise (or regenerated sound). T
37、his International Standard describes configurations at the inlet side providing for a predominant fundamental mode that suffers the least attenuation. For the outlet side, it describes anechoic terminations and measurement procedures which are not sensitive to reflections or which allow for specifie
38、d corrections. Furthermore, this International Standard gives guidance on the suppression of flanking transmission and noise signals. The transmission loss of an air-terminal unit is determined from the results of measurements in a reverberation room and theoretical reflection coefficients of a subs
39、titution duct. The insertion loss of a silencer is generally affected by the airflow. The insertion loss is therefore preferably measured with superimposed airflow if the silencer is to be used in ducts with high flow velocity. For absorptive silencers where the maximum internal flow velocity falls
40、short of 20 m/s, the flow will hardly have an effect on the insertion loss. In practice, non-uniform flow distributions will occur. Therefore, the limit velocity of 20 m/s may correspond to a design velocity of 10 m/s to 15 m/s. An airflow through a silencer regenerates noise. This flow noise (or re
41、generated sound) establishes the lowest sound pressure level that can be achieved after the silencer. It is, therefore, necessary to know the sound power level of the flow noise (or regenerated sound) behind the silencer. This is preferably determined in a reverberation room connected to the object
42、via a transmission element. In accordance with this International Standard, the total pressure loss of a silencer to be used with flow is to be determined. It is, therefore, useful to equip the test facility with the instruments and devices necessary for the determination of the total pressure loss.
43、 EN ISO 7235:2003 Licensed Copy: sheffieldun sheffieldun, na, Mon Nov 20 03:08:57 GMT+00:00 2006, Uncontrolled Copy, (c) BSI Licensed Copy: sheffieldun sheffieldun, na, Mon Nov 20 03:08:57 GMT+00:00 2006, Uncontrolled Copy, (c) BSI INTERNATIONAL STANDARD ISO 7235:2003(E) I SO 3002 All irhgts seredev
44、r 1 Acoustics Laboratory measurement procedures for ducted silencers and air-terminal units Insertion loss, flow noise and total pressure loss 1 Scope This International Standard specifies methods for determining the insertion loss, in frequency bands, of ducted silencers with and without airflow, t
45、he sound power level, in frequency bands, of the flow noise (or regenerated sound) generated by ducted silencers, the total pressure loss of silencers with airflow, and the transmission loss, in frequency bands, of air-terminal units. The measurement procedures are intended for laboratory measuremen
46、ts at ambient temperature. Measurements on silencers in situ are specified in ISO 11820. It is to be noted that the results determined in a laboratory according to this International Standard will not necessarily be the same as those obtained in situ (installation), as different sound and flow field
47、s will yield different results. For example, the pressure loss will be lower under laboratory conditions than in situ, but will be comparable between different laboratories. This International Standard is applicable to all types of silencer including silencers for ventilating and air- conditioning s
48、ystems, air intake and exhaust of flue gases, and similar applications. Other passive air-handling devices, such as bends, air-terminal units or T-connectors, can also be tested using this International Standard. This International Standard is not applicable to reactive silencers used for motor vehi
49、cles. NOTE 1 Annex A specifies the sound field excitation equipment. Annex B gives requirements for the transition element. Annex C gives details of duct walls and limiting insertion loss. Annex D specifies how to convert one-third-octave band attentuation values to octave band values. Annex E gives requirements for measurements on large parallel-baffle silencers. Annex F specifies a test of longitudinal attenuation. Annex G gives guidelines on anechoic terminat