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 978-0-626-21059-5 SANS 1451-1:2008Edition 1.2Any reference to SABS 1451-1 is deemedto be a reference to this standard(Government Notice No. 1373 of
4、8 November 2002)SOUTH AFRICAN NATIONAL STANDARD Hearing protectors Part 1: Ear-muffs 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 SANS 1451-1:2008
5、 Edition 1.2 Table of changes Change No. Date Scope Amdt 1 1991 Amended to change the minimum attenuation value for the band centre frequency of 125 Hz. Amdt 2 2008 Amended to change the designation of SABS standards to SANS standards, to change the NOTE in the subclause on seal pressure (3.4.3) to
6、ordinary text, and to update referenced standards. Acknowledgement The South African Bureau of Standards wishes to acknowledge the valuable assistance derived from publications of the following organizations: British Standard Institution International Organization for Standardization Foreword This S
7、outh African standard was approved by National Committee StanSA TC 76, Acoustics, electro-acoustics and vibration, in accordance with procedures of Standards South Africa, in compliance with annex 3 of the WTO/TBT agreement. This document was published in March 2008. This document supersedes SABS 14
8、51-1:1991 (edition 1.1). A vertical line in the margin shows where the text has been technically modified by amendment No. 2. SANS 1451 consists of the following parts, under the general title Hearing protectors: Part 1: Ear-muff. Part 2: Ear-plugs. Part 3: Ear-muffs attached to an industrial safety
9、 helmet. SANS 1451-1:2008 Edition 1.2 1Contents Page Acknowledgement Foreword 1 Scope 3 2 Definitions . 3 3 Requirements 4 4 Marking . 6 5 Information 7 6 Inspection and methods of test . 7 6.1 Inspection . 7 6.2 Samples, conditioning and sequence of testing . 7 6.3 Test for headband force . 8 6.4 S
10、eal pressure test . 9 6.5 Drop test . 10 6.6 Vibration test . 10 6.7 Headband durability test . 10 6.8 Determination of insertion loss . 11 6.9 Seal leakage test 14 Figures 1-7 . 15-20 Appendix A Applicable standards 21 Appendix B Quality evaluation of ear-muffs produced to the requirements laid dow
11、n in this part of the specification 21 SANS 1451-1:2008 Edition 1.2 2This page is intentionally left blankSANS 1451-1:2008 Edition 1.2 3Hearing protectors Part 1: Ear-muffs 1 Scope 1.1 This part of the specification covers constructional, design and performance requirements for ear-muffs intended fo
12、r use as hearing protectors. 1.2 Real-ear attenuation characteristics of the ear-muffs are measured in accordance with the subjective method specified in ISO 4869-1. Amdt 2 NOTE a) Ear-plugs are covered in SANS 1451-2. b) The standards referred to in this part of the specification are listed in appe
13、ndix A. c) Guidance on the verification of the quality of ear-muffs produced to this part of the specification is given in appendix B. 2 Definitions 2.1 For the purposes of this part of the specification the following definitions shall apply: attenuation the algebraic difference, in decibels, betwee
14、n the one-third octave band pressure level, as perceived by a real ear at threshold, in a specified sound field under specified conditions, with the hearing protector absent and with the hearing protector being worn decibel dB a ratio of sound pressures given by the formula 2110/log20ppdB = where p1
15、 = first sound pressure, Pa p2 = reference sound pressure = 20 Pa. SANS 1451-1:2008 Edition 1.2 4earcup shell a hollow, approximately hemispherical component that is mounted on a headband and to which a cushion and a liner are usually fitted ear-muff a hearing protector that circumaurally occludes t
16、he ears headband a band, usually of metal or plastics, designed to hold the ear-muffs securely over the ears by exerting a clamping force headstrap a flexible strap fitted to the earcups (or to the headband close to the earcups) of a pair of ear-muffs and that can be adjusted to support the ear-muff
17、s (usually behind-the-head types) by resting on the top of the head insertion loss the algebraic difference, in decibels, between the one-third octave band pressure level, measured by the microphone of an acoustic test fixture (see 6.8.1(a) in a specified sound field under specified conditions, with
18、 the hearing protector absent and with the hearing protector affixed. liner material contained within an earcup that can increase the attenuation of the ear-muff at certain frequencies pink noise noise of which the sound pressure spectral density is inversely proportional to frequency seal cushion a
19、 deformable cover, usually of foam plastics or liquid-filled, fitted to the rim of an earcup to improve the comfort and fit of ear-muffs 3 Requirements 3.1 Materials Materials of seals which may come into contact with the skin shall be non-staining, soft, pliable and not known to cause skin irritati
20、on or to have any adverse effect on health. 3.2 Design 3.2.1 All parts of a pair of ear-muffs shall be so designed and manufactured that they are not likely to cause any injury to the wearer when they are used as intended. 3.2.2 All parts that are in contact with plastics seals shall be rounded, fin
21、ished smooth and shall be free from sharp edges which could cause damage to the seals. 3.2.3 Where the seals are not intended to last the lifetime of the ear-muffs, the seals shall be replaceable without the use of any tools. 3.3 Dimensions 3.3.1 The longest dimension of the opening of an ear-muff w
22、ith the seals fitted (measured in the plane of the face of the earcup), shall be at least 50 mm, and the width of the opening (measured in the plane of the face of the earcup and at right angles to the longest dimension) shall be at least 35 mm. SANS 1451-1:2008 Edition 1.2 53.4 Performance 3.4.1 De
23、formation of seals Any seal deformation which is present when the ear-muffs are unpacked shall disappear within 30 minutes. 3.4.2 Headband force When a pair of ear-muffs is tested in accordance with 6.3, using the relevant head size settings given in table 1, the headband force shall not exceed 16 N
24、. 3.4.3 Seal pressure When a pair of ear-muffs is tested in accordance with 6.4, using the relevant head size settings given in table 1, the seal pressure shall not exceed 4 kPa. Table 1 Head size settings for headband force and seal pressure tests 1 2 3 4 Head size settings* mm Type of ear-muff Hea
25、d width Head height Head depth Over-the-head 150 130 Not applicable Behind-the-head 150 Not applicable 105 * See also figure 1. Ear-muffs designed to fit very large or very small heads shall be marked as such (see 4.1(e) and the midpoint of the range of head dimensions that they are designed to fit
26、shall be stated by the manufacturer. In this case, when headband force and seal pressure are being measured, these median settings shall be used instead of the settings given in table 1. 3.4.4 Attenuation When a pair of ear-muffs is tested in accordance with the method described in ISO 4869-1, the a
27、ttenuation determined for each one-third octave band shall be at least equal to the values given in table 2. Amdt 2 In the case of universal type ear-muffs, attenuation values shall be determined for both modes of use, and both shall at least comply with the appropriate values given in table 2. Tabl
28、e 2 Minimum attenuation values 1 2 Band centre frequencyHz Attenuation minimum dB 125 250 500 10 15 21 1 000 2 000 4 000 8 000 29 31 32 26 Amdt 1SANS 1451-1:2008 Edition 1.2 6NOTE Ear-muffs used for protection against high energy impulsive noise, e.g. certain military applications, will require high
29、er attenuation values in order to be effective. 3.4.5 Resistance to damage when dropped When a pair of ear-muffs is tested in accordance with 6.5, they shall not crack, rupture or otherwise suffer damage likely to affect their performance. 3.4.6 Resistance to vibration When a pair of ear-muffs is te
30、sted in accordance with 6.6, they shall not crack, rupture or otherwise suffer damage likely to affect their performance. 3.4.7 Headband durability When a pair of ear-muffs is tested in accordance with 6.7, they shall not crack, rupture or otherwise suffer damage likely to affect their performance.
31、3.4.8 Change of headband force When a pair of ear-muffs is re-tested in accordance with 6.3 after they have been tested in accordance with 6.5-6.7, the headband force shall not differ by more than 25 % from that originally determined. 3.4.9 Change in insertion loss When a pair of ear-muffs is tested
32、 in accordance with 6.8, both before and after testing in accordance with 6.3, 6.5, 6.6 and 6.7, the insertion loss determined shall not differ by more than 4 dB at more than one test frequency. 3.4.10 Resistance to leakage When a liquid-filled or gas-filled seal is tested in accordance with 6.9, it
33、 shall not leak. 4 Marking 4.1 Each pair of ear-muffs shall be legibly and indelibly marked with the following information: a) the manufacturers name, trade mark or other identification; b) the model designation and batch number; c) when the ear-muff is intended by the manufacturer to be used in a p
34、articular orientation, an indication of the “FRONT“ or “TOP“ (or both) of the earcup; d) if the total mass of a pair of ear-muffs is greater than 400 g, the total mass of the ear-muffs; e) when the ear-muff is designed by the manufacturer to fit a very large or a very small head, the word “LARGE“ or
35、 “SMALL“, as appropriate; and f) when the earcup is intended by the manufacturer to be worn over a particular ear, an indication of the “RIGHT“ and “LEFT“ earcup. SANS 1451-1:2008 Edition 1.2 75 Information 5.1 Information sheet The following information shall be provided in an information sheet sup
36、plied with each pair of ear-muffs: a) guidance on ensuring correct selection and fit of the ear-muffs; b) the method of fitting and adjustment; c) a description of the type of strap and of the seals; d) a recommended method of cleaning (which does not require the use of cleaning agents that are know
37、n to be harmful to the health of the wearer or detrimental to the performance of the ear-muffs); e) details of any maintenance required; f) the address of the manufacturer, importer or distributor; g) the warning “Hearing protector seals may deteriorate with use and will then need replacement“, h) t
38、he information required when ordering new seals; and i) if appropriate, the method of seal replacement. 5.2 Background technical information The following information shall be available on request: a) attenuation results, measured and presented using the procedures given in ISO 4869-1. In the case o
39、f universal type ear-muffs (where the straps can be used either as headband or neck band), attenuation values shall be provided for both modes of use; Amdt 2 b) results of tests carried out in accordance with this part of the specification; c) the date and place of test; and d) the name of the test
40、institute. 6 Inspection and methods of test 6.1 Inspection Visually examine each pair of ear-muffs for compliance with the requirements of section 4 and those requirements of section 3 for which tests to assess compliance are not given in 6.3-6.9 (inclusive.) 6.2 Samples, conditioning and sequence o
41、f testing 6.2.1 Samples Ear-muffs shall be submitted for testing in the condition and packing in which they are offered for sale. SANS 1451-1:2008 Edition 1.2 86.2.2 Conditioning Samples shall be conditioned and tested in an atmosphere having a temperature of 22 5 C and a relative humidity in the ra
42、nge 25-85 %. 6.2.3 Sequence of testing The sequence of testing shall be as follows: a) Condition the ear-muffs for 4,5 0,5 h with all adjustments set to their mid-positions. b) Check the sample for compliance with 3.4.1-3.4.4, in that order. c) Determine the insertion loss of the sample, using the p
43、rocedure given in 6.8, and record the values. d) Check the sample for compliance with 3.4.5-3.4.7, in that order. e) Condition the sample for 16 0,5 h. f) Check the sample for compliance first with 3.4.8 and then with 3.4.9. g) If appropriate, check the sample for compliance with 3.4.10. 6.3 Test fo
44、r headband force 6.3.1 Apparatus As shown in figure 2. NOTE To ensure low friction, it is recommended that precision mechanical parts be used for the linear ball bearing and its associated hardened and ground spindle. 6.3.2 Setting-up and calibration a) Connect the force transducer to a suitable ind
45、icator. b) So slide the thrust plate that its spindle does not touch the transducer. The indicator should read zero. If necessary, adjust the “zero“ preset control on the indicator. c) With light finger-pressure, push the thrust plate down onto the transducer until the indicator reads approximately
46、0,5 N, then gently release. The indicator should read zero. Repeat several times. A “return“ reading of 0,1 N or greater indicates an equipment fault. d) So position the apparatus that the thrust plate is uppermost and its spindle is vertical. e) Place a known calibration mass on the thrust plate. N
47、ote the indicator reading, which should be the weight of the thrust plate, the spindle, the coupling pin and the calibration mass. If necessary, adjust the “gain“ preset control on the indicator. f) Remove the calibration mass. Return equipment to the original position and repeat (b) and (c) above.
48、g) Repeat (d)-(f) above until consistent settings are found. SANS 1451-1:2008 Edition 1.2 96.3.3 Procedure a) Over-the-head type ear-muffs 1) Adjust the separation of the plates to the appropriate head width dimension given in table 1. 2) Adjust the headband support pad centrally between the moving
49、plates and to the appropriate head height given in table 1. 3) Adjust the headband to its longest position. 4) So fit the ear-muffs onto the apparatus that the seals are central on the plates. Adjust the headband until it touches the headband support. 5) Adjust the headband support pad to its lowest position, being careful not to move the ear-muffs under test. Ensure that only the seals of the ear-muffs are in contact with the apparatus. NOTE Some ear-muffs may not remain in their correct position without the support of the headband. In this case, rotate the entire ap
