1、BS EN ISO7235:2009ICS 91.120.20NO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAWBRITISH STANDARDAcoustics Laboratorymeasurementprocedures for ductedsilencers and air-terminal units Insertion loss, flownoise and totalpressure loss (ISO7235:2003)This British Standardwas published
2、under theauthority of the StandardsPolicy and StrategyCommittee on 30 April2010 BSI 2010ISBN 978 0 580 67420 4Amendments/corrigenda issued since publicationDate CommentsBS EN ISO 7235:2009National forewordThis British Standard is the UK implementation of EN ISO 7235:2009. Itis identical to ISO 7235:
3、2003. It supersedes BS EN ISO 7235:2003 whichis withdrawn.The UK participation in its preparation was entrusted to TechnicalCommittee EH/1/4, Machinery noise.A list of organizations represented on this committee can be obtained onrequest to its secretary.This publication does not purport to include
4、all the necessary provisionsof a contract. Users are responsible for its correct application.Compliance with a British Standard cannot confer immunityfrom legal obligations.EUROPEAN STANDARDNORME EUROPENNEEUROPISCHE NORMEN ISO 7235August 2009ICS 91.120.20 Supersedes EN ISO 7235:2003 English VersionA
5、coustics - Laboratory measurement procedures for ductedsilencers and air-terminal units - Insertion loss, flow noise andtotal pressure loss (ISO 7235:2003)Acoustique - Modes opratoires de mesure en laboratoirepour silencieux en conduit et units terminales - Pertedinsertion, bruit dcoulement et perte
6、 de pression totale(ISO 7235:2003)Akustik - Labormessungen an Schalldmpfern in Kanlen -Einfgungsdmpfung, Strmungsgerusch undGesamtdruckverlust (ISO 7235:2003)This European Standard was approved by CEN on 20 July 2009.CEN members are bound to comply with the CEN/CENELEC Internal Regulations which sti
7、pulate the conditions for giving this EuropeanStandard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such nationalstandards may be obtained on application to the CEN Management Centre or to any CEN member.This European Standard e
8、xists in three official versions (English, French, German). A version in any other language made by translationunder the responsibility of a CEN member into its own language and notified to the CEN Management Centre has the same status as theofficial versions.CEN members are the national standards b
9、odies of Austria, Belgium, Bulgaria, Cyprus, Czech Republic, Denmark, Estonia, Finland,France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal,Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom.EUR
10、OPEAN COMMITTEE FOR STANDARDIZATIONCOMIT EUROPEN DE NORMALISATIONEUROPISCHES KOMITEE FR NORMUNGManagement Centre: Avenue Marnix 17, B-1000 Brussels 2009 CEN All rights of exploitation in any form and by any means reservedworldwide for CEN national Members.Ref. No. EN ISO 7235:2009: EBS EN ISO 7235:2
11、009EN ISO 7235:2009 (E) 3 Foreword The text of ISO 7235:2003 has been prepared by Technical Committee ISO/TC 43 “Acoustics” of the International Organization for Standardization (ISO) and has been taken over as EN ISO 7235:2009 by Technical Committee CEN/TC 211 “Acoustics” the secretariat of which i
12、s held by DS. This European Standard shall be given the status of a national standard, either by publication of an identical text or by endorsement, at the latest by February 2010, and conflicting national standards shall be withdrawn at the latest by February 2010. Attention is drawn to the possibi
13、lity that some of the elements of this document may be the subject of patent rights. CEN and/or CENELEC shall not be held responsible for identifying any or all such patent rights. This document supersedes EN ISO 7235:2003. This document has been prepared under a mandate given to CEN by the European
14、 Commission and the European Free Trade Association, and supports essential requirements of EC Directives. For relationship with EC Directives, see informative Annexes ZA and ZB, which are integral parts of this document. According to the CEN/CENELEC Internal Regulations, the national standards orga
15、nizations of the following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, R
16、omania, Slovakia, Slovenia, Spain, Sweden, Switzerland and the United Kingdom. Endorsement notice The text of ISO 7235:2003 has been approved by CEN as a EN ISO 7235:2009 without any modification. BS EN ISO 7235:2009EN ISO 7235:2009 (E) 4 Annex ZA (informative) Relationship between this European Sta
17、ndard and the Essential Requirements of EU Directive 98/37/EC This European Standard has been prepared under a mandate given to CEN by the European Commission and the European Free Trade Association to provide a means of conforming to Essential Requirements of the New Approach Directive 98/37/EC, am
18、ended by 98/79/EC on machinery. Once this standard is cited in the Official Journal of the European Communities under that Directive and has been implemented as a national standard in at least one Member State, compliance with the normative clauses of this standard confers, within the limits of the
19、scope of this standard, a presumption of conformity with the relevant Essential Requirements of that Directive and associated EFTA regulations. WARNING - Other requirements and other EU Directives may be applicable to the product(s) falling within the scope of this standard. BS EN ISO 7235:2009EN IS
20、O 7235:2009 (E) 5 Annex ZB (informative) Relationship between this European Standard and the Essential Requirements of EU Directive 2006/42/EC This European Standard has been prepared under a mandate given to CEN by the European Commission and the European Free Trade Association to provide a means o
21、f conforming to Essential Requirements of the New Approach Directive 2006/42/EC on machinery. Once this standard is cited in the Official Journal of the European Communities under that Directive and has been implemented as a national standard in at least one Member State, compliance with the normati
22、ve clauses of this standard confers, within the limits of the scope of this standard, a presumption of conformity with the relevant Essential Requirements of that Directive and associated EFTA regulations. WARNING Other requirements and other EU Directives may be applicable to the product(s) falling
23、 within the scope of this standard. BS EN ISO 7235:2009ISO 7235:2003(E) ISO 2003 All rights reserved iiiContents Page Foreword iv Introduction v 1 Scope 1 2 Normative references . 1 3 Terms and definitions. 2 4 Symbols . 7 5 Test facilities and requirements for instrumentation 9 5.1 Purpose and type
24、s of test facilities. 9 5.2 Equipment for acoustic testing of silencers 9 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 So
25、und 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 Transit
26、ions. 30 7.6 Anechoic termination . 30 7.7 Reverberation room 30 7.8 Acoustical test results 30 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 element 34
27、Annex C (normative) Duct walls and limiting insertion loss 37 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 4
28、3 Annex G (informative) Anechoic terminations. 44 Annex H (informative) Examples of measurement arrangements. 46 Bibliography . 48 BS EN ISO 7235:2009ISO 7235:2003(E) iv ISO 2003 All rights reservedForeword ISO (the International Organization for Standardization) is a worldwide federation of nationa
29、l 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 the right to be represented on that committee. Internation
30、al 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. International Standards are drafted in accordance with the rules
31、 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. Publication as an International Standard requires approval by at le
32、ast 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 rights. ISO 7235 was prepared by Technical Committee ISO/TC 43,
33、 Acoustics, Subcommittee SC 1, Noise. This second edition cancels and replaces the first edition (ISO 7235:1991), which has been technically revised. BS EN ISO 7235:2009ISO 7235:2003(E) ISO 2003 All rights reserved vIntroduction This International Standard specifies the substitution method for deter
34、mining the insertion loss of ducted silencers and a method for determining the transmission loss of air-terminal units. In the substitution method, the sound pressure level of the transmitted wave is first determined for the test object and then when the test object has been replaced by the substitu
35、tion 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 field. The methods are listed in order of preference. The acoustic performance of silencers depends on the modal composition of the sound
36、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). This International Standard describes configurations at the inlet side providing for a predominant fundamental mode that suffers the leas
37、t attenuation. For the outlet side, it describes anechoic terminations and measurement procedures which are not sensitive to reflections or which allow for specified corrections. Furthermore, this International Standard gives guidance on the suppression of flanking transmission and noise signals. Th
38、e transmission loss of an air-terminal unit is determined from the results of measurements in a reverberation room and theoretical reflection coefficients of a substitution duct. The insertion loss of a silencer is generally affected by the airflow. The insertion loss is therefore preferably measure
39、d 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 short of 20 m/s, the flow will hardly have an effect on the insertion loss. In practice, non-uniform flow distributions will occur. Ther
40、efore, 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 regenerated sound) establishes the lowest sound pressure level that can be achieved after the silencer. It is, therefore, necessary to kno
41、w 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 via a transmission element. In accordance with this International Standard, the total pressure loss of a silencer to be used with flow i
42、s 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. BS EN ISO 7235:2009BS EN ISO 7235:2009INTERNATIONAL STANDARD ISO 7235:2003(E) ISO 2003 All rights reserved 1Acoustics Laboratory measur
43、ement 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, the sound power level, in freque
44、ncy 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 measurements at ambient temperature. Meas
45、urements 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 fields will yield different results.
46、 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 systems, air intake and exhaust o
47、f 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 vehicles. NOTE 1 Annex A specifies t
48、he 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 o
49、n large parallel-baffle silencers. Annex F specifies a test of longitudinal attenuation. Annex G gives guidelines on anechoic terminations and Annex H shows examples of measurement arrangements. NOTE 2 Acoustic testing of air-terminal devices and fan-coil units is to be carried out as described for air-terminal units. NOTE 3 Sound power measurements on air-terminal units are specified in ISO 5135. Measurements of the pressure loss of air-terminal units are described in EN 12238, EN 12239 and EN 12589. 2 Normative references The follo
