1、January 2010DEUTSCHE NORM English price group 22No part of this standard may be reproduced without prior permission ofDIN Deutsches Institut fr Normung e. V., Berlin. Beuth Verlag GmbH, 10772 Berlin, Germany,has the exclusive right of sale for German Standards (DIN-Normen).ICS 17.140.99!$2“1565815ww
2、w.din.deDDIN EN ISO 7235Acoustics Laboratory measurement procedures for ducted silencers andair-terminal units Insertion loss, flow noise and total pressure loss (ISO 7235:2003)English version of DIN EN ISO 7235:2010-01Akustik Labormessungen an Schalldmpfern in Kanlen Einfgungsdmpfung, Strmungsgerus
3、ch und Gesamtdruckverlust (ISO 7235:2003)Englische Fassung DIN EN ISO 7235:2010-01SupersedesDIN EN ISO 7235:2004-02www.beuth.deDocument comprises 59 pagesDIN EN ISO 7235:2010-01 2 National foreword This standard has been prepared by Technical Committee ISO/TC 43 “Acoustics”, Subcommittee SC 1 “Noise
4、” (Secretariat: DS, Denmark), Working Group WG 44 “Noise control by silencers” in collaboration with Technical Committee CEN/TC 211 “Acoustics” (Secretariat: DS, Denmark). The responsible German body involved in its preparation was the Normenausschuss Akustik, Lrmminderung und Schwingungstechnik im
5、DIN und VDI (Acoustics, Noise Control and Vibration Engineering Standards Committee in DIN and VDI), Working Committee NA 001-02-02 AA Schallschutzeinrichtungen (Schall-dmpfer, Kapseln, elastische Lagerung), Working Group NA 001-02-02-01 AK Schallschutz in Strmungs-kanlen. Amendment of the European
6、Machinery Directive has made it necessary to review Annex Z in terms of the essential requirements of EU Directive 98/37/EC and the revised Directive, 2006/42/EC. The technical substance of the standard has not been changed. The DIN Standards corresponding to the International Standards referred to
7、in this document are as follows: ISO 3741 DIN EN ISO 3741 ISO 5725-6 DIN ISO 5725-6 ISO 3746 DIN EN ISO 3746 ISO 9614-3 DIN EN ISO 9614-3 ISO 5135 DIN EN ISO 5135 ISO 11200 DIN EN ISO 11200 ISO 5136 DIN EN ISO 5136 ISO 11820 DIN EN ISO 11820 ISO 5167-1 DIN EN ISO 5167-1 ISO 14163 DIN EN ISO 14163 IS
8、O 5725-1 DIN ISO 5725-1 IEC 60651 DIN EN 61672 (all parts) ISO 5725-2 DIN ISO 5725-2 IEC 60804 DIN EN 61672 (all parts) ISO 5725-3 DIN ISO 5725-3 IEC 60942 DIN EN 60942 ISO 5725-4 DIN ISO 5725-4 IEC 61260 DIN EN 61260 ISO 5725-5 DIN ISO 5725-5 The national standards are given in Annex NA “Bibliograp
9、hy”. Amendments This standard differs from DIN EN ISO 7235:2004-02 as follows: a) Annexes ZA and ZB have been supplemented to show the relationship between this standard and the Machinery Directive 98/37/EC and the new revised Machinery Directive 2006/42/EC. Previous editions DIN 45646: 1988-09 DIN
10、EN ISO 7235: 1995-09 DIN EN ISO 7235: 2004-02 DIN EN ISO 7235:2010-01 3 National Annex NA (informative) Bibliography DIN EN 60942, Electroacoustics Sound calibrators DIN EN 61260, Electroacoustics Octave-band and fractional-octave-band filters DIN EN 61672-1, Electroacoustics Sound level meters Part
11、 1: Specifications DIN EN 61672-2, Electroacoustics Sound level meters Part 2: Pattern evaluation tests DIN EN 61672-3, Electroacoustics Sound level meters Part 3: Periodic tests DIN EN ISO 3741, Acoustics Determination of sound power levels of noise sources using sound pres-sure Precision methods f
12、or reverberation rooms DIN EN ISO 3746, Acoustics Determination of sound power levels and sound energy levels of noise sources using sound pressure Survey method using an enveloping measurement surface over a reflecting plane DIN EN ISO 5135, Acoustics Determination of sound power levels of noise fr
13、om air-terminal devices, air-terminal units, dampers and valves by measurement in a reverberation room DIN EN ISO 5136, Acoustics Determination of sound power radiated into a duct by fans and other air-moving devices In-duct method DIN EN ISO 5167-1, Measurement of fluid flow by means of pressure di
14、fferential devices inserted in circular cross-section conduits running full Part 1: General principles and requirements DIN ISO 5725-1, Accuracy (trueness and precision) of measurement methods and results Part 1: General principles and definitions DIN ISO 5725-2, Accuracy (trueness and precision) of
15、 measurement methods and results Part 2: Basic method for the determination of repeatability and reproducibility of a standard measurement method DIN ISO 5725-3, Accuracy (trueness and precision) of measurement methods and results Part 3: Intermediate measures of the precision of a standard measurem
16、ent method DIN ISO 5725-4, Accuracy (trueness and precision) of measurement methods and results Part 4: Basic methods for the determination of the trueness of a standard measurement method DIN ISO 5725-5, Accuracy (trueness and precision) of measurement methods and results Part 5: Alternative method
17、s for the determination of the precision of a standard measurement method DIN ISO 5725-6, Accuracy (trueness and precision) of measurement methods and results Part 6: Use in practice of accuracy values DIN EN ISO 9614-3, Acoustics Determination of sound power levels of noise sources using sound inte
18、n-sity Part 3: Precision method for measurement by scanning DIN EN ISO 11200, Acoustics Noise emitted by machinery and equipment Guidelines for the use of basic standards for the determination of emission sound pressure levels at a work station and at other specified positions DIN EN ISO 7235:2010-0
19、1 4 DIN EN ISO 11820, Acoustics Measurements on silencers in situ DIN EN ISO 14163, Acoustics Guidelines for noise control by silencers EUROPEAN STANDARDNORME EUROPENNEEUROPISCHE NORMEN ISO 7235August 2009ICS 91.120.20 Supersedes EN ISO 7235:2003 English VersionAcoustics - Laboratory measurement pro
20、cedures 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 de pression totale(ISO 7235:2003)Aku
21、stik - 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 stipulate the conditions for giving this
22、 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 exists in three official versions (Eng
23、lish, 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 bodies of Austria, Belgium, Bulgaria,
24、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.EUROPEAN COMMITTEE FOR STANDARDIZATIONCO
25、MIT 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: EContentsPage Foreword .3 Introduction.4 1 Scope5 2 No
26、rmative references5 3 Terms and definitions .6 4 Symbols11 5 Test facilities and requirements for instrumentation 13 5.1 Purpose and types of test facilities.13 5.2 Equipment for acoustic testing of silencers 13 5.3 Equipment for acoustic testing of air-terminal units.19 5.4 Equipment for flow testi
27、ng .20 5.5 Equipment for dynamic testing25 6 Test procedures.26 6.1 General .26 6.2 Insertion loss .26 6.3 Transmission loss.28 6.4 Sound power level of the flow noise (or regenerated sound).28 6.5 Volume flow rate and pressure loss coefficient.29 7 Information to be recorded.33 7.1 Description of t
28、he test object.33 7.2 Instrumentation .33 7.3 Sound-source equipment .34 7.4 Test, substitution and transmission ducts.34 7.5 Transitions .34 7.6 Anechoic termination34 7.7 Reverberation room 34 7.8 Acoustical test results 34 7.9 Measurement uncertainty.35 8 Information to be reported35 Annex A (nor
29、mative) Design of the sound field excitation equipment and qualification tests36 Annex B (normative) Transmission element38 Annex C (normative) Duct walls and limiting insertion loss41 Annex D (normative) Conversion of one-third-octave-band attenuation values to octave-band attenuation values.44 Ann
30、ex E (normative) Measurements on large parallel-baffle silencers 45 Annex F (normative) Test of longitudinal attenuation 47 Annex G (informative) Anechoic terminations.48 Annex H (informative) Examples of measurement arrangements .50 Bibliography52 Annex ZA (informative) Relationship between this Eu
31、ropean Standard and the Essential Requirements of EU Directive 98/37/EC54 Annex ZB (informative) Relationship between this European Standard and the Essential Requirements of EU Directive 2006/42/EC55 2 DIN EN ISO 7235:2010-01 EN ISO 7235:2009 (E) Foreword 3 EN ISO 7235:2009 (E) DIN EN ISO 7235:2010
32、-01 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 is held by DS. This European Sta
33、ndard 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 possibility that some of the elements
34、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 Commission and the European Fr
35、ee 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 organizations of the following coun
36、tries 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, Romania, Slovakia, Slovenia, Spa
37、in, 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. Introduction This International Standard specifies the substitution method for determining the insertion loss of ducted silencers and
38、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 substitution duct. The sound pressure level of the transmi
39、tted 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 field at the inlet and on reflections at the outle
40、t 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 least attenuation. For the outlet side, it describes a
41、nechoic 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. The transmission loss of an air-terminal unit is det
42、ermined 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 measured with superimposed airflow if the silencer is to
43、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. Therefore, the limit velocity of 20 m/s may correspond
44、 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 know the sound power level of the flow noise (or rege
45、nerated 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 is to be determined. It is, therefore, useful to eq
46、uip the test facility with the instruments and devices necessary for the determination of the total pressure loss. 4 DIN EN ISO 7235:2010-01 EN ISO 7235:2009 (E) 1 Scope This International Standard specifies methods for determining the insertion loss, in frequency bands, of ducted silencers with and
47、 without airflow, the 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 la
48、boratory measurements 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 s
49、ound and flow fields 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 systems, 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
