ISO-10494-1993.pdf
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1、INTERNATIONAL STANDARD ISO 10494 First edition 1993-07-01 Gas turbines and gas turbine sets - Measurement of emitted airborne noise - Engineeringlsurvey method Turbines 2 gaz et groupes de turbines 8 gaz - Mesurage du bruit akien 6mis - Methode dexpertiselde contr6le Reference number ISO 10494:1993(
2、E) ISO 10494:1993(E) Foreword ISO (the International Organization 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. Esch member body interested in a
3、subject for which a technical committee has been established has 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
4、 (IEC) on all matters of electrotechnical standardization. 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 least 75 % of the member bodies casting a vote. International
5、Standard ISO 10494 was prepared jointly by Technical Com- mittees lSO/TC 192, Gas turbines and lSO/rC 43, Acoustics. Annex A forms an integral part of this International Standard. Annexes B, C and D are for information only. 0 ISO 1993 All rights reserved. No part of this publication may be reproduc
6、ed or utilized in any form or by any means, electronie or mechanical, including photocopying and microfilm, without per- mission in writing from the publisher. International Organization for Standardization Case Postale 56 l CH-l 211 Geneve 20 l Switzerland Printed in Switzerland ii ISO 10494:1993(E
7、) Introduction Control of noise from machines or equipment requires effective exchange of acoustical information among the several Parties concerned. These in- clude the manufacturer, specifier, installer and user of the machine or equipment. This acoustical information is obtained from measurements
8、. These measurements are useful only if they are carried out under speci- fied conditions to obtain defined acoustical quantities using standardized instruments. The Sound power level data determined according to this International Standard is essentially independent of the environment in which the
9、data are obtained. This is one of the reasons for using Sound power level to characterize the Sound emitted by various types of machine equipment. Sound power level data are useful for: a) calculating the approximate Sound pressure Ievel at a given distance from a machine operating in a specified en
10、vironment; b) comparing the noise radiated by machines of the same type and size; c) comparing the noise radiated by machines of different types and sizes; d) determining whether a machine camplies with a specified upper limit of noise emission; e) planning in Order to determine the amount of transm
11、ission loss or noise control required under certain circumstances; f) engineering work to assist in developing quiet machinety and equip- ment. This International Standard gives requirements for the measurement of the noise emission of gas turbine and gas turbine Sets. lt has been pre- pared in acco
12、rdance with ISO 3740 on the basis of ISO 3744. Due to the special conditions concerning gas turbines and gas turbine Sets, it is necessary to define different noise sources and to use measurement surfaces differing from those specified in ISO 3744. . . . 111 -,-,- This page intentionally left blank
13、INTERNATIONAL STANDARD ISO 10494:1993(E) Gas turbines and gas turbine sets - Measurement of emitted airborne noise - Engineeringlsurvey method 1 Scope 1 .l This International Standard specifies methods for measuring the Sound pressure levels on a measurement surface enveloping a Source, and for calc
14、ulating the Sound power Ievel produced by the Source. lt gives requirements for the test environment and instrumentation, as weil as techniques for ob- taining the surface Sound pressure Ievel from which the A-weighted Sound power level of the Source and octave or one-third-octave band Sound power I
15、evels are calculated. This method may be used to perform acceptance tests. 1.2 The aim of this International Standard is a grade 2 (engineering) result (see table 1). When the correction for background noise exceeds the limit of 1,3 dB but is less than 3 dB, and/or the correction for environment exc
16、eeds the limits of 2 dB but is less than 7 dB, then a grade 3 (Survey) result is obtained. 1.3 This International Standard applies to gas tur- bines and gas turbine sets - for industrial applications (e.g. stationary), - for installation on board ships, or offshore instal- lations, road and railway
17、vehicles. lt does not apply to gas turbines in aircraft appli- cations. 1.4 The methods defined in this International Stan- dard apply to the measurement of the noise emission of a gas turbine or gas turbine set under steady-state operating conditions. The results are expressed as Sound pressure Iev
18、els, and Sound power levels in A- weighted and in octave bands. 1.5 Measurements made in conformity with this International Standard should result in Standard devi- ations which are equal to or less than those given in table3. The uncertainties in table 3 depend not only on the accuracies with which
19、 Sound pressure Ievels and measurement surface areas are determined, but also on the “near-fieId error” which increases for smaller measurement distances and lower fre- quencies (i.e. those below 250 Hz). The near-field er- ror always leads to Sound power Ievels which are higher than the real Sound
20、power levels. NOTES 1 If the methods specified in this International Standard are used to compare the Sound power levels of similar ma- chines that are omnidirectional and radiate broad-band noise, the uncertainty in this comparison tends to result in Standard deviations which are less than those gi
21、ven in table3, provided that the measurements are performed in the same environment with the same shape of measure- ment surface. 2 The Standard deviations given in table3 reflect the cumulative effects of all Causes of measurement uncer- tainty, excluding variations in the Sound power levels from t
22、est to test which may be caused, for example, by changes in the mounting or operating conditions of the Source. The reproducibility and repeatability of the test result may be considerably better (i.e. smaller Standard deviations) than the uncertainties given in table3 would indicate. -,-,- ISO 1049
23、4:1993(E) Table 1 - International Standards specifying various methods for determining the Sound power levels of machines and equipment Inter- national Classification Test Volume of Character of Sound power Optional levels information Standard of methodl) environment*) Source noise obtainable availa
24、ble ISO 3741 Steady, broad- Reverberation band Precision room meeting In one-third- (grade 1) Steady, octave or A-weighted Sound specified re- ISO 3742 quirements discrete- octave bands power level Preferably less frequency or than 1 % of test narrow-band room volume Steady, broad- Engineering Speci
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