1、 Collection of SANS standards in electronic format (PDF) 1. Copyright This standard is available to staff members of companies that have subscribed to the complete collection of SANS standards in accordance with a formal copyright agreement. This document may reside on a CENTRAL FILE SERVER or INTRA
2、NET SYSTEM only. Unless specific permission has been granted, this document MAY NOT be sent or given to staff members from other companies or organizations. Doing so would constitute a VIOLATION of SABS copyright rules. 2. Indemnity The South African Bureau of Standards accepts no liability for any
3、damage whatsoever than may result from the use of this material or the information contain therein, irrespective of the cause and quantum thereof. ISBN 978-0-626-19405-5 SANS 1470-2:2008Edition 1.2 Any reference to SABS 1470-2 is deemedto be a reference to this standard(Government Notice No. 1373 of
4、 8 November 2002)SOUTH AFRICAN NATIONAL STANDARD Sound power labelling Part 2: Welding generators Published by Standards South Africa 1 dr lategan road groenkloof private bag x191 pretoria 0001 tel: 012 428 7911 fax: 012 344 1568 international code + 27 12 www.stansa.co.za Standards South Africa SAN
5、S 1470-2:2008 Edition 1.2 Table of changes Change No. Date Scope Amdt 1 1999 Amended to facilitate reference to SABS ISO 3744 (which replaced SABS 0195 that is currently referenced) and to correct the criteria for the adequacy of the test environment and the background noise. Amdt 2 2008 Amended to
6、change the designation of SABS standards to SANS standards, and to update referenced standards and the requirement regarding the operation of the welding generator (4.3.4(b). Acknowledgement Standards South Africa wishes to acknowledge the valuable assistance derived from publications of the followi
7、ng organizations: Council of the European Communities International Organization for Standardization Foreword This South African standard was approved by National Committee StanSA TC 76, Acoustics, electro-acoustics and vibration, in accordance with procedures of Standards South Africa, in complianc
8、e with annex 3 of the WTO/TBT agreement. This document was published in February 2008. This document supersedes SABS 1470-2:1999 (edition 1). A vertical line in the margin shows where the text has been technically modified by amendment No. 2. SANS 1470-2:2008 Edition 1.2 1 Contents Page Acknowledgem
9、ent Foreword 1 Scope . 3 2 Definitions. 3 3 Requirements . 4 3.1 Labelling . 4 3.2 Noise emission . 4 4 Inspection and testing. 5 4.1 Inspection . 5 4.2 Test for noise emission. 5 4.3 Modifications to the test method described in SANS 3744 5 Amdt 1 Appendix A Applicable standards 7 Appendix B Two-su
10、rface method to determine the environmental correction K2for in-situ measurements 8 Amdt 1 SANS 1470-2:2008 Edition 1.2 2 This page is intentionally left blank SANS 1470-2:2008 Edition 1.2 3 Sound power labelling Part 2: Welding generators 1 Scope 1.1 This part of the specification covers the requir
11、ements for the labelling of welding generators with a noise emission value and specifies the test method to be used for the verification of the labelled value. NOTE a) The standards referred to in this part of the specification are listed in appendix A. b) The “two-surface method“ (see A.4.3 of SANS
12、 3744) to determine the environmental correction is given in appendix B. Amdt 1 c) This part of the specification refers to SANS 3744 and specifies an engineering method for measuring the sound pressure levels at prescribed microphone positions on a rectangular parallelepiped surface that envelops t
13、he welding generator under investigation. Amdt 1 d) For planning purposes, additional information would be required, e.g. measurements of the octave or one-third octave band pressure levels. 2 Definitions 2.1 For the purposes of this part of the specification, the definitions given in SANS 3744 and
14、the following definitions shall apply: Amdt 1 A-weighted sound power level, in decibels LWAthe sound power level of a machine, determined in accordance with the test method specified in this part of the specification, with frequency weighting A (see SANS 656, SANS 658, SANS 61672-1 and SANS 61672-2)
15、 selected on the measuring instruments Amdt 2 batch a number of welding generators of the same performance and manufactured to the same technical specification by one manufacturer NOTE A batch may be either an entire production series or a portion thereof. SANS 1470-2:2008 Edition 1.2 4 batch labell
16、ing a single labelled value Lc, applied to a batch of welding generators labelled value Lcan integer value, determined by the manufacturer1), representing the maximum sound power level of a welding generator near (sound) field a sound field near a sound source where instantaneous sound pressure and
17、particle velocity are substantially out of phase welding generator any rotary device that produces an electric current suitable for use for electric arc welding 3 Requirements 3.1 Labelling Each welding generator shall bear a label that contains at least the following information: a) The labelled va
18、lue Lc; b) the letter “B“ or “I“ to indicate batch labelling or individual labelling, respectively; c) identification of the labelled product by means of the serial number. NOTE 1) As an example, the labelling for a stationary welding generator of a given power could be as follows: Labelling Interpr
19、etation(B) Lc97 23456 “(B)“ indicates that this welding generator is one of a batch that are labelled with the same value: 97. The labelled value in accordance with this part of the specification is 97. “23456“ is the serial number of the welding generator. 2) The labelled value may be displayed on
20、the existing rating plate affixed to the welding generator. 3) For assessment purposes, e.g. the existence of tonal components, or for planning purposes, additional spectral information for different operating conditions would be required. 3.2 Noise emission When tested in accordance with 4.2, a wel
21、ding generator shall have an A-weighted sound power level LWAnot exceeding the labelled value Lc. 1) Guidelines for the determination of the labelled value Lc by the manufacturer are given in ISO 7574 (parts 2 to 4). Amdt 2 SANS 1470-2:2008 Edition 1.2 5 4 Inspection and testing 4.1 Inspection Inspe
22、ct each welding generator for compliance with 3.1. 4.2 Test for noise emission NOTE The standard deviation of A-weighted sound power level LWAcalculated in accordance with this part of the specification is approximately 2 dB for a source that emits noise without pronounced spectral deviations. Use t
23、he test method described in SANS 3744, modified as described in 4.3, to determine the A-weighted sound power level LWAof the welding generator and check for compliance with 3.2. Amdt 1 4.3 Modifications to the test method described in SANS 3744 Amdt 1 4.3.1 Criterion for adequacy of the test environ
24、ment (see 4.1 and 4.2 of SANS 3744) Amdt 1 When the test is to be carried out indoors, use one of the methods described in annex A of SANS 3744 to determine the environmental correction K2. Amdt 1 If the environmental correction K2 exceeds 2 dB, the test environment is not suitable for measurements
25、in accordance with this part of the specification. Amdt 1 NOTE See note (b) to 1.1. Amdt 1 4.3.2 Criterion for background noise Amdt 1 Determine the correction for the background noise (K1) in accordance with 8.3 of SANS 3744. Amdt 1 Averaged over the microphone positions, the level of the backgroun
26、d noise shall be at least 6 dB, but preferably more than 15 dB, below the sound pressure level to be measured. Amdt 1 4.3.3 Instrumentation (see section 5 of SANS 3744) Amdt 1 When integrating the squared signal over a fixed time-interval, use an integrating device or system that complies with the r
27、equirements of SANS 656, SANS 658, SANS 61672-1 and SANS 61672-2. Amdt 1; amdt 2 4.3.4 Installation and operation of the welding generator (see section 6 of SANS 3744) Amdt 1 a) Installation. Place a skid-mounted welding generator on supports of height 0,40 m, unless otherwise required in the manufa
28、cturers conditions of installation. b) Operation. Use the welding generator in accordance with the manufacturers recommendations. Amdt 2 SANS 1470-2:2008 Edition 1.2 6 4.3.5 Measurement surface and microphone positions (see 7.3 of SANS 3744) Amdt 1 a) Measurement surface. Use a rectangular parallele
29、piped at a constant distance of 1 m from the reference surface. b) Key microphone positions (see figure C.2 of SANS 3744). Use the microphone positions described in 7.3.1 of SANS 3744. Amdt 1 c) Additional microphone positions (see 7.3.2 of SANS 3744). If measurements at additional microphone positi
30、ons are required, choose these positions in accordance with figure C.1 of SANS 3744. Amdt 1 d) Reduction of number of microphone positions. The nine key points may be reduced to five (numbers 1, 2, 3, 4 and 9 in figure C.2 of SANS 3744) if it has been proven that the surface sound pressure level det
31、ermined in this way on a similar welding generator does not deviate by more than 1,0 dB from the value determined using nine key points. Amdt 1 NOTE The overhead microphone position may be omitted for safety purposes. Amdt 1 4.3.6 Measurement of the A-weighted sound pressure level (see 7.5 of SANS 3
32、744) Amdt 1 Obtain the following data: a) the A-weighted sound pressure level during operation of the welding generator under test; and b) the A-weighted sound pressure level of the background noise with the welding generator inoperative. 4.3.7 Calculation of the A-weighted sound power level Calcula
33、te the A-weighted sound power level of the welding generator in accordance with section 8 of SANS 3744. Amdt 1 SANS 1470-2:2008 Edition 1.2 7 Appendix A Applicable standards Reference is made to the latest issues of the following standards: ISO 7574-1, Acoustics Statistical methods for determining a
34、nd verifying stated noise emission values of machinery and equipment Part 1: General considerations and definitions. ISO 7574-2, Acoustics Statistical methods for determining and verifying stated noise emission values of machinery and equipment Part 2: Methods for stated values for individual machin
35、es. ISO 7574-3, Acoustics Statistical methods for determining and verifying stated noise emission values of machinery and equipment Part 3: Simple (transition) method for stated values for batches of machines. ISO 7574-4, Acoustics Statistical methods for determining and verifying stated noise emiss
36、ion values of machinery and equipment Part 4: Methods for stated values for batches of machines. SANS 656, Sound level meters. Amdt 2 SANS 658, Integrating-averaging sound level meters. Amdt 2 SANS 3744/ISO 3744, Acoustics Determination of sound power levels of noise sources using sound pressure Eng
37、ineering method in an essentially free field over a reflecting plane. Amdt 1 SANS 61672-1/IEC 61672-1, Electroacoustics Sound level meters Part 1: Specifications. Amdt 2 SANS 61672-2/IEC 61672-2, Electroacoustics Sound level meters Part 2: Pattern evaluation tests. Amdt 2 SANS 1470-2:2008 Edition 1.
38、2 8 Appendix B Two-surface method to determine the environmental correction K2for in-situ measurements Amdt 1 (This appendix forms part of the requirements of the specification) B.1 General Normally, the noise level of a welding generator is determined outdoors under free-field conditions or in spec
39、ial test rooms for which the environmental correction has been determined. Determination of the sound pressure level of a welding generator can, in some cases, only be carried out in situ, with the result that the acoustic environment is far from ideal. The environmental correction K2which needs to
40、be applied in such cases, may be determined in accordance with the absolute comparison test, or by using one of the methods based on room absorption (see annex A of SANS 3744). The method given in this appendix is based on the “two-surface method“ given in A.4.3 of SANS 3744. Amdt 1 B.2 Measurement
41、surfaces and microphone locations For the qualification of the environment, use two measurement surfaces as follows: a) The first is the same surface as is used when the sound power level of the welding generator under test is being determined and this area is designated S1; b) the second is geometr
42、ically similar to the first one, but located further away from the welding generator under test. The area of this measurement surface is designated S2. A ratio of S2to S1, approximately equal to 4, is recommended. The microphone positions on the second measurement surface are chosen to correspond wi
43、th those for the measurement surface used for the determination of the sound power level. NOTE The determination of the environmental correction K in the range of the ratio S2/S1around 1,0 is less accurate because of the unavoidable errors in the determination of L. The area ratio S2/S1in the range
44、1,0 S2/S1 2,0 should therefore not be used unless it is unavoidable. B.3 Test procedure Calculate the surface sound pressure levels in each frequency band, for the two measurement surfaces. Calculate the difference L to the nearest 0,5 dB: L = 12 ppLL where1pL = the surface sound pressure level, dB,
45、 determined by using the measurement surface S1 2pL = the surface sound pressure level, dB, determined by using the measurement surface S2Determine the environmental correction K from the value of L and the area ratio S2/S1by using figure B.1. SANS 1470-2:2008 Edition 1.2 9 Use this value of K for K
46、2in equation (8) of SANS 3744. Amdt 1 B.4 Qualification requirement The sound field in the vicinity of the measurement surface S1is satisfactory for measurements in accordance with this part of the specification if K is less than or equal to 2 dB. If the above requirement is not fulfilled, the measu
47、rement surface S1may be replaced with a new measurement surface S1, closer to the test source but outside its near field. The procedure described in B.3 is then repeated for this new measurement surface. If the qualification requirement is fulfilled for S1, and if this new measurement surface is out
48、side the near field of the actual sound source, then use S1in the determination of the sound power level of the actual sound source. If the qualification requirement cannot be fulfilled for the measurement surface S1, repeat the procedure with a new measurement surface closer to the sound source unt
49、il a measurement surface is found for which the qualification requirement is fulfilled and which is outside the near field of the actual sound source being tested. If such a measurement surface cannot be found, the test environment cannot be used. SANS 1470-2:2008 Edition 1.2 10 Area ratio S2/S1K = 1212log1011log10SSMSSM = 100,1LFigure B.1 Environmental correction K for measurement areas S1 S2(for measurements on the actual measurement surface S1 and on a surface S2further from the source) Standards South Africa
