1、BRITISH STANDARD BS EN IS0 14163:1998 Incorporating 4mendmentNo. 1 Acoustics - Guidelines for noise control by silencers The European Standard EN IS0 14163A998 has the status of a British Standard ICs 17.140.90 NO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGH LAW BS EN IS0 14163:199
2、8 National foreword This British Standard is the English language version of EN IS0 14163A998. It is identical with IS0 14163:1998. The UK participation in its preparation was entrusted by Technical Committee EW1, Acoustics, to Subcommitke EWll4, Machinery noise, which has the responsibility to: - a
3、id enquirem to undersand the text, - present to the responsible internationavEuropean committee any enquiries on the interpretation, or proposals for change, and keep the UK interests informed; - monitor related international and European developments and promulgate them in the UK. A list of organiz
4、ations represented on this subcommittee can be obtained on request to its secretary. Cross-references Attention is drawn to the fact that CEN and CENELEC Standards normally include an annex which lists normative references to international publications with their comesponing European publications. T
5、he British Standards which implement these internationai or European publications may be found in the BSI Standards Catalogue under the section entitled “Internaiional Standards Correspondence Index”, or by using the “Find” facility of the BSI Standards Electronic Catalogue. A British Standard does
6、not purport to include all the necessary provisions of a coninut 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 f
7、ront cover, the EN IS0 title page, the EN IS0 foreword page, the IS0 title page, pages ii to v, a blank page, pages 1 to 45 and a back cover. The BSI copyright notice displayed throughout this document indicates when the document was last issued. This British Standard, having Amendments issued since
8、 publication been prepared under the direction of the Health and Environment Sector Committee, was published under the authority of the Standards 10529 Committee and comes into effect on 15 December 1998 Amd. No. Date July 1999 I (g BSI 07-1999 ISBN O 580 30661 6 Comments Adds annex zk EUROPEAN STAN
9、DARD NORME EUROPENNE EUROPISCHE NORM EN IS0 14163 October 1998 ICs 17.140.01 Descriptors: see IS0 document English version Acoustics - Guidelines for noise control by silencers (IS0 141 63:1998) Acoustique - Lignes directrices pour la reduction du bruit au moyen de silencieux (IS0 14163:1998) Akusti
10、k - Richtlinien Mr den Schallschutz durch SaialMBmpfer (IS0 141 63: 1998) This European Standard was approved by CEN on 21 September 1998. CEN members are bound to comply with the CENICENELEC Intemal Regulations which aipulate lhe conditions for giving this European Standard the status of a national
11、 standard without any alteration. Up-to-date lists and Mbiiographiical 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 ot
12、her language made by translation under the responsibility of a CEN member into its own language and notified to the CentraJ Secretariat has the sme status as vie official versions. CEN members are the national standards bodies of Austria, Belgium. Czech Republic. Denmark, Finiand. France. - for prev
13、enting or reducing sound transmission through ventilation openings from rooms with high inside sound levels; - for attenuating blow-off noise generated by high-pressure lines; - for attenuating intake and exhaust noise generated by internal combustion engines; and - for attenuating intake and outlet
14、 noise from fans, compressors and turbines. They are classified according to their types, performance characteristics and applications. Active and adaptive passive noise-control systems are not covered in detail in this International Standard. 2 Normative references The following normative documents
15、 contain provisions which, through reference in this text, constitute provisions of this Intemational Standard. For dated references, subsequent amendments to, or revisions of, any of these publications do not apply. However, parties to agreements based on this International Standard are encouraged
16、to investigate the possibility of applying the most recent editions of the normative documents indicated below. For undated references, the latest edition of the normative document referred to applies. Members of IS0 and IEC maintain registers of currently valid International Standards. IS0 3741, Ac
17、oustics - Determination of sound power levels of noise sources using sound pressures - Precision methods for reveheration rooms. IS0 3744, Acoustics - Determination of sound power levels of noise sources - Engineering methods for free-field conditions over a reflecting plane. IS0 7235, Acoustics - M
18、easurement procedures for ducted silencers - Insertion loss, flow noise and total pressure loss. IS0 11691, Acoustics - Measurement of insertion loss of ducted silencers without flow - Laboratory survey method. IS0 11820, Acoustics - Testing of silencers in situ. 1 EN IS0 14163:1998 3 Terms and defi
19、nitions For the purposes of this International Standard, the following terms and definitions apply. 3.1 silencer device reducing sound transmission through a duct, a pipe or an opening without preventing the transport of the medium 3.2 dissipative silencer absorptive silencer silencer providing for
20、broad-band sound attenuation with relatively little pressure loss by partially converting sound energy to heat through friction in porous or fibrous duct linings 3.3 reactive silencer general term for reflective and resonator silencers where the majority of the attenuation does not involve sound ene
21、rgy dissipation 3.4 reflective silencer silencer providing for single or multiple reflections of sound by changes in the cross-section of the duct, duct linings with resonators, or branchings to duct sections with different lengths 3.5 resonator silencer silencer providing for sound attenuation at w
22、eakly damped resonances of elements NOTE 3.6 blow-off silencer silencer used in steam blow-off and pressure release lines throttling the gas flow by a considerable pressure loss in porous material and providing sound attenuation by lowering the flow velocity at the exit and reacting on the source of
23、 the sound (such as a valve) The elements may or may not contain absorbent material. 3.7 active silencer silencer providing for the reduction of sound through interference effects by means of sound generated by controlled auxiliary sound sources NOTE Mostly low-order modes of sound in ducts are affe
24、cted. 3.8 adaptive passive silencer silencer with passive sound-attenuating elements dynamically tuned to the sound field 3.9 insertion loss, Di difference between the levels of the sound powers propagating through a duct or an opening with and without the silencer NOTE 1 The insertion loss is expre
25、ssed in decibels, dB. NOTE 2 Adapted from IS0 7235. 2 STD-BSI BS EN IS0 LLiLb3-ENGL 1998 D Lb2Libb9 0785b79 Lb2 D EN IS0 14163:1998 3.10 insertion sound pressure level difference difference between the sound pressure levels occurring at an immission point, without a significant level of extraneous s
26、ound, without and with the silencer installed Di, NOTE 1 The insertion sound pressure level difference is expressed in decibels, dB. NOTE 2 Adapted from IS0 11 820. 3.1 1 transmission loss difference between the levels of the sound powers incident on and transmitted through the silencer NOTE 1 NOTE
27、2 often differ due to limited measurement possibilities. NOTE 3 Dt The transmission loss is expressed in decibels, dB. For standard test laboratories D, equals Di, whereas results for D, and Di obtained from in situ measurements may Adapted from IS0 11820. 3.1 2 discontinuity attenuation that portio
28、n of the insertion loss of a silencer or silencer section due to discontinuities Ds NOTE The discontinuity attenuation is expressed in decibels, dB. 3.13 propagation loss decrease in sound pressure level per unit length which occurs in the midsection of a silencer with constant cross- section and un
29、iform longitudinal design, characterizing the longitudinal attenuation of the fundamental mode Da NOTE The propagation loss is expressed in decibels per metre, dB/m. 3.14 outlet reflection loss difference between the levels of the sound power incident on and transmitted through the open end of a duc
30、t NOTE Dm The outlet reflection loss is expressed in decibels, dB. 3.15 modes spatial distributions (or transverse standing wave patterns) of the sound field in a duct that occur independently from one another and suffer a different attenuation NOTE higher attenuation. The fundamental mode is least
31、attenuated. In narrow and in lined ducts, higher-order modes suffer substantially 3.16 cut-on frequency lower frequency limit for propagation of a higher-order mode in a hard-walled duct NOTE 1 NOTE 2 speed of sound and C is the duct diameter. In a rectangular duct with larger dimension H, fcH = 0,5
32、ch. The cut-on frequency is expressed in hertz, Hz. In a duct of circular cross-section, the cut-on frequency for the first higher-order mode isf c= 0,57dC where c is the 3 STD-BSI BS EN IS0 LLiLb3-ENGL 1778 1b24bb9 0785b80 78Y EN IS0 14163:1998 3.17 pressure loss difference between the mean total p
33、ressures upstream and downstream of the silencer AR NOTE 1 NOTE 2 3.1 8 regenerated sound flow noise flow noise caused by the flow conditions in the silencer. The pressure loss is expressed in pascals, Pa. Adapted from IS0 7235. NOTE Sound power levels of regenerated sound and pressure losses measur
34、ed in laboratory tests are related to a laterally uniform flow distribution at the inlet of the silencer. If this uniform flow distribution is not attainable under in situ conditions, for example because of the upstream duct design, higher levels of regenerated sound and higher pressure losses will
35、occur. 4 Specification, selection and design considerations 4.1 Requirements to be specified 4.1.1 In general, the sound pressure level (A-weighted, one-third-octave or full-octave) shall not exceed a specified value at a specified position (e.g. at a work station, in the neighbourhood, or in a recr
36、eation room). The permissible contribution from a sound source can then be determined in terms of the sound power level and the directivity index of that source using sound propagation laws and requirements concerning the allocation of contributions to several partial sound sources. The required ins
37、ertion loss of the silencer is given by the difference between the permissible and the actual sound power level of the source. In simple cases where the sound immission is determined solely by the sound source to be attenuated, the necessary insertion sound pressure level difference of the silencer
38、can be calculated directly from the difference between the permissible and the actual sound pressure level at the immission point. When the difference in directivity indices with and without the silencer is negligible, the insertion sound pressure level difference equals the insertion loss of the si
39、lencer. 4.1.2 The permissible pressure loss shall not be exceeded. NOTE This requirement should be specified as clearly as possible. Instead of the imprecise specification “as small as possible“, a sensible limit value has to be found. Even if the pressure loss is considered as “not critical“, a lim
40、it value should be determined from the maximum permissible flow velocity that may not be exceeded for reasons of mechanical stability, regenerated sound or energy consumption costs. 4.1.3 The permissible size of the silencer shall be kept as small as possible (for reasons of cost and weight). NOTE T
41、here is a minimum size which (given the state of the art) cannot be reduced. This size depends on the required reduction in sound level, the permissible pressure loss and on other restrictions concerning materials to be used (or avoided), resistance to different kinds of stress, etc. 4.1.4 Additiona
42、l requirements (concerning materials, durability, leakages, etc.) result from the application of the silencer in hot, dusty, humid or aggressive gases, in pressure lines or for high sound pressure levels and vibration levels, and from the combination of silencers with devices for the control of exha
43、ust gas, sparks and particles. 4.2 Selection and layout of silencers Specific information on silencers can be drawn from - laboratory measurements made in accordance with IS0 7235; - silencer manufacturers test data; 4 STD-BSI BS EN IS0 LLiLb3-ENGL 1998 M lbZqbb9 078Sb81 810 m EN IS0 14163:1998 - th
44、eoretical models to calculate propagation loss and insertion loss for silencers with circular or rectangular cross-section: - pressure loss and regenerated sound prediction methods. The selection of a dissipative, a reactive or a blow-off silencer will be determined by its application or by referenc
45、e to the experience presented in this international Standard. Results obtained from computer programs for the insertion loss of dissipative silencers depend on the assumptions made concerning the magnitude and distribution of airflow resistance in the silencer and the acoustical effect of the cover
46、18. Certain geometrical features like off-setting of splitters or subdividing of absorbers are not easily accessible for calculation. Calculations are most accurate for parameter variations concerning design as well as operating conditions. Effects of flow on the performance of reactive silencers ar
47、e taken into account by special highly sophisticated computer software. 4.3 Design of special silencers The design of a special silencer is usually an iterative process featuring the following stages: a) rough specification of the dimensions of free ducts for the flow and of connected spaces for the
48、 distribution of sound, for example using the manufacturers declarations for similar silencers and taking into account the essential requirements and restrictions; b) construction of a model for predictive calculation or measurements; c) use of the model and comparison of the results with requiremen
49、ts concerning sound level reduction and pressure loss; d) change of dimensions and sound-absorbent materials to fulfil requirements or to optimize the design; e) constructional consideration of special requirements. 5 Types of silencers, general principles and operational considerations 5.1 Overview Silencers are used to - prevent pulsations and oscillations of the gas at the source, - reduce conversion of the pulsations and oscillations into sound energy, and - provide conversion of sound energy into heat. Table 1 - Typical advantages and shortcomings of different types of silence
