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KENYA STANDARD Hearing protectors — Part 1:

Ear-muffs — Specification

PUBLIC REVIEW STAGE JANUARY 2007

KS 2093-1:2006

KENYA STANDARD

Hearing protectors — Part 1: Ear-muffs — Specification

KENYA BUREAU OF STANDARDS (KEBS) Head office: P.O. OX 54974, Nairobi-00200, Tel.:(+254 020) 605490, 602350, Fax: (+254 020) 604031

E-Mail:info@kebs.org, Web:http://www.kebs.org Coast Region Lake Region Rift Valley Region P.O. BOX 99376, Mombasa-80100 P.O. Box 2949, Kisumu-40100 P.O. Box 2138, Nakuru-20100

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Tel.: (+254 041)229563, 230939/40 Tel.: (+254 057) 23549, 22396 Tel.:(+254 051) 210553, 210555 Fax: (+254 041) 229448 Fax: (+254 057) 212814 Fax: (+254 051) 210553 Technical Committee representation The following organizations were represented on the Technical Committee. Kenyatta University University of Nairobi Central Workshop, Kenya Railways Ministry of Health, Public Health Department Ministry of Labour, Directorate of Occupational Health and Safety Kenya Police, Traffic department Kenya Industrial Research and Development Institute Civil Aviation of Kenya Kenya Bureau of Standards — secretariat

REVISION OF KENYA STANDARDS In order to keep abreast of progress in Industry, Kenya Standards shall be regularly reviewed. Suggestions for improvement to published standards, addressed to the Managing Director, Kenya Bureau of Standards, are welcome.

© Kenya Bureau of Standards, 2007 Copyright: Users are reminded that by virtue of section of 6 of the Copyright Act, Cap. 130 of the Laws of Kenya, copyright subsists in all Kenya Standards and except as provided under section 7 of this Act, no Kenya Standard produced by Kenya Bureau of Standards may be reproduced, stored in a retrieval system in any form or transmitted by any means without prior permission in writing from the managing Director.

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Preface This Kenya Standard specifies requirement for the material, design and performance of hearing protection devices. The method of attenuation measurement specified is not suitable for determining the attenuation of devices such as electronic earmuffs. The requirements and tests of the standard are concerned primarily with physical performance. However, the standard also calls for the values of sound attenuation afforded by the ear-muffs, to be provided in order to assist purchasers in selecting the most appropriate type of ear-muffs for their needs. During the development of this standard, assistance was obtained from the following sources: BS EN 352-1:1993: British Standards ? Hearing protectors ? Safety requirements and testing ? Part 1: Earmuffs. EN 24869-1:1992: European union Standard ? Acoustics ? Hearing protectors ? Part 1: Subjective method for the measurement of sound attenuation. ISO/TR 4869-3:1989: Acoustics ? Hearing protectors ? Part 3: Simplified method for the measurement of loss of earmuff type protectors for quality inspection purposes. This assistance is hereby acknowledged. 'Field staff of other sizes may be accommodated by 'Small/Large size ear-muffs, which are required to be accompanied by information regarding the range of sizes which they are designed to fit.

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Specification for earmuffs for general use 1 Scope This Draft Kenya Standard specifies design and performance, methods of test, marking and user information for Earmuffs for general use by consumers.

2. Application 2.1 This standard does not deal with earmuffs for attachment to a helmet or which is part of a helmet. 2.2 This standard does not apply to the impulsive noise-hearing protectors. 3. Definitions For the purposes of this standard the following definitions apply. 3.1 Acoustic test fixture (ATF) A device that approximates certain dimensions of an average adult human head and is used for measuring the insertion loss of earmuffs.

3.2 Cup A hollow component, which is mounted on the headband and to which a cushion and a liner are usually fitted.

3.3 Cushion A deformable component, usually containing foam plastic or liquid filling, fitted to the rim of the cup to improve the comfort and fit of the ear-muffs on the head.

3.4 Ear-muff A hearing protector, consisting of a cup to pressed against each pinna or a circumaural cup to be pressed against the head around the pinna. The cups can be pressed against the head with a special headband or neckband. Over-the-head, earmuffs are designed to be worn with the headband passing over the top of the head. 3.5 Headband A band, usually of metal or plastics, designed to enable the ear-muffs to fit securely around the ears by exerting force against the cups and pressure through the cushions. 3.6 Helmet A device which may or may not include hearing protection and which covers a substantial part of the head. 3.7 Insertion loss The algebraic difference in decibels between the one-third octave band sound pressure level, measured by the microphone of the acoustic test fixture in a specified sound field under specified conditions, with the earmuff absent, and the sound pressure level with the ear-muff on, with other conditions identical. 3.8 Liner A device which may not include hearing protection an d which covers a substantial part of the head.

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3.9 Sound attenuation For a given test signal, the difference in decibels between the threshold of hearing, with and without the hearing protector in place, for a test subject. 3.10 Test depth Vertical distance between the axis through the centres of the mounting holes of the pinna simulators and top of the headband support, with the pinna simulators attached with their shorter axes vertical (see figure 1).

3.11 Test height Vertical distance between the axis through the centres of the mounting holes of the pinna simulators and the top of the headband support, with the pinna simulators attached with their longer axes vertical (see figure 1).

3.12 Test width Width between the two centres of the mounting holes for the pinna simulators of the mounting fixture in figure 1.

4. Sizing The requirements of 6.2 give rise to and accord with the classification of ear-muffs into two types, `normal size range' and `small/large size range'. ‘Normal size range' ear-muffs are so classified if their adjustability complies with 6.2.1.1 and 6.2.1.2 as appropriate, when assessed at the test dimensions specified in tables 1 and 3. `Small size range' earmuffs are so classified if their adjustability complies with 6.2.2.1 and 6.2.2.2 as appropriate, when assessed at the test dimensions specified in tables 2 and 3. `Large size range' earmuffs are so classified if their adjustability complies with 6.2.3.1 and 6.2.3.2 as appropriate, when assessed at the test dimensions specified in tables 2 and 3. `Small/large size range' earmuffs shall be accompanied by the information specified in 8.1 (g).

5. Materials and construction 5.1 Materials 5.1.1 Those parts of the earmuff that may come into contact with the skin shall be non-staining, soft, pliable and not known to be likely to cause skin irritation, allergic reaction or any other adverse effect on health. 5.1.2. All materials shall be visibly unimpaired after cleaning by the method specified by the manufacturer. 5.2 Construction 5.2.1 All parts of the earmuffs shall be radiused, finished smooth and be free from sharp edges. 5.2.2 Earmuffs whose cushions and/ or liners are intended by the manufacturers to be replaced by the wearer shall not require the use of tools for this purpose. 5.2.3 All universal earmuffs shall be provided with a head strap. 6 Performance

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6.1 General The requirements specified in 6.2 to 6.12 shall be satisfied. Specimens of earmuffs shall be conditioned and tested as specified in 7.1.1 and 7.1.2. The scheme of testing shall be as specified in 7.1.3.

b) plain view Note: The pinna stimulators shown in figure 2 are fitted to the plates of the fixtures so, that the holes at the centres of the simulators lie on the horizontal axis through the force transducer. Figure 1. Mounting fixture for measurement of rotation of cups and for tests for headband force and cushion pressure and for adjustability.

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6.2 Adjustability When tested in accordance with 7.2. 6.2.1 `Normal size range' earmuffs 6.2.1.1 Over-the-head and under-the-chin earmuffs For each of the combinations of test dimensions shown by the letter N in table 2, the range of adjustment of the cups/headband and of the width between the cushions shall enable the ear-muffs to be fitted to the fixture.

6.2.2 `Small size range' earmuffs 6.2.2.1 Over -the-head earmuffs For each of the combinations of test dimensions shown by the letter S in table 2, the range of adjustment of the cup/headband and of the width between the cushions shall enable the ear -muffs to be fitted to the fixture.

6.2.3 Large size range' ear muffs 6.2.3.1 Over -the-head earmuffs. For each of the combinations of test dimensions shown by the letter L in table 2, the range of adjustment of the cup/headband and of the width between the cushions shall enable the earmuffs to be fitted to the fixture. 6.3 Cup rotation When tested in accordance with 7.3, the contact between the cushions and the plates of the fixture shall be continuous insofar as it provides an unbroken barrier between the inside and outside perimeters of the cushions.

6.4 Lead and force When tested in accordance with7.4, the headband force shall be not greater than 14 N.

6.5 Cushion pressure When tested in accordance with 7.5, the cushion pressure shall be not greater than 4500 Pa. 6.6 Resistance to damage when dropped. Unless 6.7 is to be satisfied, the ear-muffs (except for replaceable cushions) shall not crack when tested in accordance with 7.6. Neither shall any part of the ear-muffs become detached, such that correct reassembly requires the use of either ~ tool or a replacement part. 6.7 Resistance to low temperature When tested in accordance with 7.7 the ear-muffs (except for replaceable cushions) shall not crack. Neither shall any part of the earmuffs become detached, such that correct re-assembly requires the use of either a tool or a replacement part.

6.8 Change in headband force (including optional resistance to high temperature). The headband force shall not change by more than ± 20% from that measured in accordance with 7.4 after the earmuffs have been subjected to the appropriate conditioning and tests specified in 7.1.3.1 to 7.1.3.12.

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6.9 Insertion loss The standard deviations reported in accordance with 7.11.4, shall be not greater than 4.0 dB in four or more adjacent one -third-octave bands, and not greater than 7.0 dB in any individual one-third-octave band.

6.10 Resistance to leakage In the case of liquid filled cushions, they shall not leak when the earmuffs are tested in accordance with 7,12.

6.10 Ignitability When tested in accordance with 7.13 no part of the earmuffs shall ignite or continue to glow after the removal of the heated rod.

6.12 Minimum attenuation. When tested in accordance with 7.14 the values (Mf-sf) of the earmuff shall be not less than the d ata in table 1.

Table 1. Attenuation requirements for earmuffs.

Table 1: Attenuation requirements for ear-muffs F in Hz (Mf -sf) in dB 125 250 500 1000 2000 4000 8000

5 8 10 12 12 12 12

Mf are the mean attenuation data and sf the standard deviations according to Appendix 1 7. Testing 7.1 Specimens conditioning an scheme of testing 7.1.1 Specimens Earmuffs shall be submitted for testing in the condition in which they are offered for sale. Ten specimens shall be submitted and they shall be numbered 1 to 10.

7.1.2 Conditioning and testing atmosphere All specimens shall be conditioned and tested in an atmosphere having a temperature of 22 °C ± 5 °C and a relative humidity of not more than 85 %, unless required otherwise by the test procedure. 7.1.3 Scheme of testing NOTE. Testing may be discontinued in the event of a specimen failing to satisfy the respectiv e requirement. The scheme of testing for the ten specimens shall be as follows (see table 2). 7.1.3:1 Unpack all earmuffs completely.

7.1.3.2 Condition all specimens for not less than 4 h in the atmosphere specified in 7.1.2. 7.1.3.3 Weigh each specimen and report the mean mass of the ten specimens to the nearest gram.

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The scheme of testing for specimens 1 to 6 shall be as follows:

Table 2: Testing scheme flow chart

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All dimensions are in mm to a tolerance of ? 0.1mm

Figure 2: Pinna simulator for the assessment of fit (only for physical measurements). 7.1.3.4 Check each specimen for compliance with the requirements of 6.2 adjustability, 6.3 cup rotation, 6.4 headband force and 6.5 cushion pressure. 7.1.3.5 Unless the optional low temperature performance requirement of 6.7 is to be tested, check each specimen for compliance with the requirements of 6.6 resistance to damage when dropped. 7.1.3.6 Optionally, check each specimen for compliance with the requirements of 6.7 resistance to low temperature. 7.1.3.7 Subject each specimen to 7.8 headband flexing. 7.1.3.8 Remove the cups (if possible) or the cushions and liners from each of the cups of each

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specimen, identifying the cups or liners to enable subsequent identical re-assembly. If the cups are removable and/or replaceable, the cushions and liners shall be protected from the water immersion during the testing. 7.1.3.9 Unless the optional high temperature conditioning of 7.1.3.10 is to be performed, subject each specimen to 7.9 water immersions. 7.1.3.10 As an option , subject each specimen to 7.10, conditioning at high temperature. 7.1.3.11 Remove each specimen from the water bath noting the time of removal and refit the cups (if removed). Remove excess water. If the liners were removed, re-fit them, and for all specimens with replaceable cushions fit new cushions to each of the cups in accordance with the manufacturer's instructions. 7.1.3.12 Condition each specimen for 60 min ± 5 min, measured from the time of removal from the water bath in 7.1.3.11. Under the conditions specified in 7.1.2, and then immediately measure the headband force in accordance with 7.4. 7.1.3.13 Condition each specimen for not less than 16 hours under the conditions specified in 7.1.2. Continue with the scheme of testing for all 10 specimens as follows: 7.1.3.14 Measure the insertion loss of each cup of each specimen in accordance with 7.11. 7.1.3.15 Calculate the standard deviation of insertion loss for all 20 cups, using (N-1) weighing for the sample data. Continue with the scheme of testing for 5 and 6 as follows: 7.1.3.16 If appropriate, check both specimens for compliance with the requirements of 6.10 resistance to leakage. 7.1.3.17 Check specimens for compliance with the requirements of clause 5, materials and construction. 7.1.3.18 Check specimens for compliance with the requirements of 6.11, ignitability. Continue with the scheme of testing for specimens 1 to 4 as follows. 7.1.3.19 Measure the sound attenuation of the specimens in accordance with 7.14. 7.2 Adjustability 7.2.1 Principle The ability of the earmuffs to be adjusted to fit specified test dimensions are assessed using a suitable mounting fixture. 7.2.2 Apparatus 7.2.2.1 Mounting fixture - the outline of an example is shown in figure 1. 7.2.2.2 Pinna simulators - the required dimensions are shown in figure 2. 7.2.2.3 Non-polar cushion adaptor. For earmuffs with non-polar cushions the manufacturer shall supply suitable adaptors, which shall be fitted to the mounting fixture. 7.2.3 Procedure 7.2.3.1 Over -the-head earmuffs 7.2.3:1.1 Fit the pinna simulators to the plates so that their longer axes are vertical and adjust the headband support to the lie midway between the plates.

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7.2.3.1.2 Adjust the cups/headband to their longest position. 7.2.3.1.3 Place the earmuffs on the fixture so that the headband is vertical and the pinna simulators are enclosed by the cushions. 7.2.3.1.4 Adjust the separation of the plates and the height of the headband support to correspond in turn and as appropriate with each of the combinations of dimensions of width and height respectivel y shown in table 2. Check whether the range of adjustment of the cups/headband and of the width between the cushions enable the ear-muffs to be fitted so that: a) the internal apex of the headband touches the headband support pad, and b) the contact between cushions and the plates of the fixtures is continuous insofar as it provides an unbroken barrier between the inside and outside perimeters of the cushions.

Table 2. Test dimensions (over-the -head and under-the-chin earmuffs) Dimensions are in millimetres

Width Head depth 125 145 155

75 S N - 90 N N N 105 - N L N indicates ear -muffs `normal' size range S indicates ear -muffs `small' size range L indicates ear -muffs `large' size range - Indicates no requirements Note. The dimensions given in table 2 have chosen to cover appropriate combinations of the head width and head height of the 5th, 50th and 95th “percentiles” of the adult population.

7.2.2 Report Report the observations noted according to 7.2.3.1.4 and 7.2.3. 7.3 Cup rotation 7.3 Cup rotation 7.3.1 Principle The earmuffs are set to be at a given adjustment and the ability of the cups to accommodate a range of angular movement is tested using a suitable mounting fixture. 7.3.2 Apparatus 7.3.2.1 Mounting fixture - the outline of an example is shown in figure 1. 7.3.2.2 Pinna simulators - the required dimensions are shown in figure 2. 7.3.2.3 Non-polar cushion adaptor. For ear-muffs with non -polar cushions, the Manufacturer shall supply suitable adaptors which shall be fitted to the mounting fixture. 7.3.3 Procedure 7.3.3.1 Fit the pinna simulators to the plates of the apparatus so that their longer axes are vertical for over-the-chin earmuffs or so that their shorter axes are vertical for behind-the-head earmuffs. 7.3.3.2 Adjust the two plates so that they are angled 5 degrees top edges out and their separation, measured on the horizontal centre line is 145 mm.

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7.3.3.3 Place the earmuffs on the fixture so that the headband is vertical and the cushions enclose the pinna simulators. Set the cups/headband to the mid-point of the range of their adjustment. 7.3.3.4 Simultaneously, rotate the plates ± 5 ° about a second axis still in the plane of the plates but orthogonal to the horizontal axis used. 7.3.3.5 Observe whether the contact between the cushions and the plates is continuous throughout this range. 7.3.4 Report Report the observations noted according to 7.3.3.5. 7.4 Headband force 7.4.1 Principle The earmuffs are set to be at a given adjustment and the force exerted through the cushions on to plates which are supporting them is then measured by a method which does not involve a significant change in the separation of the plates. 7.4.2 Apparatus 7.4.2.1 Mounting fixture - the outline of an example shown in figure 1. This fixture measures electronically the force exerted. The pinna simulators are not fitted for this test. 7.4.2.2 Non-polar cushion adaptor. For earmuffs with non-planar cushions the manufacturer shall supply suitable adaptors, which shall be fitted to the mounting fixture. 7.4.3 Procedure 7.4.3.1 Adjust the two plates so that they are parallel and the separation o f their outer surfaces is 145 mm. 7.4.3.2 Place the earmuffs on to the fixture with the headband vertical. The opening in the cushions shall be in a position so that their centres coincide with the mounting holes in the places for the pinna simulators (s ee figure 1).

Adjust the cups/headband of normal size range' ear -muffs to correspond to test height of 130 mm for overhead models. Adjust the cups /headband of small/large size range earmuffs to the midpoint of range of adjustment. Ensure that the headband is not in contact with any part of the fixtures. 7.4.3.3 Read the force indicator 2 minutes after first releasing the ear-muffs in 7.4.3.2. 7.4.3.4 Report Report the force in Newton from 7.4.3.3. Determine and report the mean value of headband force for specimens 1 to 6 tested. 7.5 Cushion pressure 7.5.1.1 Principle The earmuffs are set to be a given adjustment and the force exerted through the cushions on to plates, which are supporting them, is then measured by a method which does not involve a significant change in between one of the cushions, and the plate is also measured.

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This latter requirement is necessary as the force exerted by headband may not be uniformity distributed around the surface of the cushion area of actual contact and will almost certainly be less than the superficial area of the cushion. This requirement precludes the use of special rigs or amounting for the cups in isolation or merely pressing them on the plane by hand. 7:5.2 Apparatus 7.5.2.1 Mounting fixtures- the outline of an example is shown in figure 1. This fixture measures electronically the force exerted. The pinna simulators are not fitted for this test. 7.5.2.2 Marking medium. For example, dilute lithographic ink, white petroleum jelly or emulsion paint. g means for contact area, for example, planimeter. 7.5.2.3 Non-Planar cushion adaptor, for earmuffs with non-planar cushions the manufacturer shall supply suitable adaptors, which shall be fitted to the mounting fixture. 7.5.3 Procedure Note: It is recommended that this test is performed simultaneously with the measurement of headband force described in 7.4. 7.5.3.1 Adjust the two plates so that they are parallel , and the separation of their outer surfaces is 145 mm. Fasten a piece of paper, size just larger than that of the surface of the cushion, to the outer surface of one of the plates. 7.5.3.2 Coat one of the cushions with the marking medium. 7.5.3.3 Place the earmuffs on to the fixture with the headband vertical. The opening in the cushions shall be positioned so that their centres coincide with the mounting holes in the plates for the Pinna simulators (see figure 1)

Adjust the cup/headband of `normal size range' size earmuffs to a height of 130 mm for over-the-head models.

Adjust the cup/headband of `small /large size range' size earmuffs to the mid-point of the range adjustments.

Ensure that an impression of the coated cushion is obtained on the paper. Ensure that the cups, headband or any part of the earmuffs are not in contact with any part of the fixture in such a way as to effect the force measurement.

7.5.3.4 Read the force indicator 2 minutes after first releasing the headband in 7.5.3.3 and remove the earmuffs from the fixture. 7.5.3.5 Remove the piece of paper from the fixture and measure the area of the impression of the cushion contact area. Include in the measurement the area of any voids falling totally within the contact area. 7.5.3.6 Calculate the cushion pressure in Pascal. 7.5.4 Report Report the cushion pressure in Pascal. 7.6 Resistance to damages a w hen dropped 7.6.1 Principle The earmuffs are dropped from a specified height on to a steel plate.

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7.6:2 Apparatus 7.6.2.1 Smooth steel plate, not less than 1 cm thick. A suitable size would be 50 cm x 50 cm. 7.6.2:2 Means of suspending earmuffs, approximately 1.5 m above the plate. 7.6.3 Procedure. 7.6.3.1 Place the steel plate on a level floor. 7.6.3.2 Set the cup/headband to the mid-point of their range of adjustments. 7.6.3.3 Suspend the earmuffs by the centre of the headband with the cups pointing downwards, so that the height of the lowest point of the earmuffs is 1.5m±1 cm above the steel plate. 7.6.3.4 Drop the earmuffs once to the plate and note whether any part of the ear-muffs (except for replaceable cushions) has cracked or has become detached. Note: If any part of the earmuff becomes detached, it should be re-assembled and the testing scheme continued, provided that correct re-assembly can be performed without the use of either a tool or a replacement part. 7.6.4 Report Report whether any part of the earmuffs has cracked or has become detached. 7.7 Resistance to low temperature (optional) 7.7.1 Principle The earmuffs are conditioned at-20°C and dropped from a specified height on to a steel plate. 7.7.2 Apparatus 7.7.2.1 Refrigerated chamber maintained at a constant temperature-20° C±3°C. 7.7.2.2 Smooth steel plate, not less than 1 cm thick, suitable size would be 50 cm x 50 cm. 7.7.2.3 Means of suspending earmuffs, approximately 1.5 above the plate. 7.7.3 Procedure 7.7.3.1 Place the steel plate on a level floor. 7.7.3.2 Set the cup/headband to the mid-point of their range of adjustment. 7.7.3.3 Store the earmuffs from the refrigerated chamber for a period of at least 4 hours. 7.7.3.4 Remove the earmuffs within the refrigerated chamber and within 10 seconds, complete 7 .7.3.5 and 7.7.3.6 below. 7.7.3.5 Suspend the earmuffs by the centre of the headband with the cups pointing downwards, so that the height of the lowest point of the earmuffs is 1.5mm ? 1cm above the steel plate. 7.7.3.6 Drop the earmuffs on the plate and note whether any part of the ear-muffs (except for replaceable cushions) has cracked or has become detached. Note: If any part of the earmuffs becomes detached, it should be re-assembled and the testing scheme continued, provided that correct re-assembly can be performed without the use of either a tool replacement part.

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7.7.4 Report . Report whether any part of the earmuffs has cracked or has become detached. 7.8 Headband flexing 7.8.1 Principle The earmuffs are set to be at a given adjustment and the headband is flexed to a standard extent for a specified number of items. 7.8.2 Apparatus

Flexing device, providing essentially sinusoidal relative movement between two parallel plates - the outline of an example is shown in figure 3. 7.8.3 Procedure 7.8.3.1 Set the cups/headband to the mid-point of the range of their adjustment. If the cups/headband setting tends to change, the adjusted position shall be secured, for example, by means of adhesive tape. Such means shall not interfere with the normal pivoting of the cups on the headband. 7.8.3.2 Place the earmuffs on to the apparatus and secure the cups to the plates using, for example, elasti c bands. 7.8.3.3 Adjust the minimum separation of the plates to correspond with the free state separation of the earmuffs' cushions, or to 25 mm, whichever is the greater. 7.8.3.4 Adjust the maximum separation of the plates to 200 mm ± 5 mm. 7.8:3.5 Cycle the earmuffs between the minimum and maximum separations for 1000 cycles per minute: Note. Ensure that throughout the test no part of the headband touches any object that will interfere with its mechanical action. 7.9 Water immersion 7.9.1 Principle After removal of all replaceable parts, the earmuffs are conditioned by immersion in water. 7.9.2 Apparatus 7.9.2 Water bath containing water maintained at a constant temperature of 50 °C ± 2 °C. 7.9.2.2 Means to hold the earmuffs beneath the surface of the water. 7.9.3 Procedure After removal of the cups (if possible) or cushions and liners from the ear-muffs, immerse the remaining component of the ear-muffs in the water-bath for 24h± 1 h. If the cups are not removable, and the cushions or liner are not removable or replaceable, the cushions and liners shall be protected from water immersion during testing.

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Figure 3: Headband Flexing Apparatus .

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7.10 Conditioning at high temperature (50°C) optional) 7.10.1 Principle After removal of the liners the earmuffs are conditioned by immersion in water, with a plane parallel spacer between the cushions. 7.10.2 Apparatus 7.10.2.1 Water bath containing water maintained at constant temperature of 50°C ?2°C . 7.10.2.2 Means to hold earmuffs beneath the surface of the water. 7.10.2.3 A plane parallel spacer separating the cushions by a distance of 145 mm. 7.10.3 Procedure After removal of the liners (but without removal of the cushions) the ear -muffs are placed over the spacer with the cups/headband set to the position specified in 7.4.3.2. Immerse the earmuffs with the spacer in the water bath for 24h± 1h. If the cushions are not replaceable they shall be protected from water immersion during testing. 7.11 Insertion loss 7.11.1 Principle The insertion loss of each cup of the earmuffs is measured at specified one-third octave band centre frequencies. 7.11.2 Apparatus

The requirement equipment, including acoustic test fixture and test site, is described in ISO/TR 4869-3. 7.11.3 Procedure

ISO/TR 4869-3 shall be used, subject to the following modifications. 7.11.3.1 Either the random incidence sound field or the plane progressive wave may be used. However, if 6.9 is not satisfied, the test shall be repeated using the random incidence field.

7.11.3.2 The insertion loss of each cup shall be measured at one -third octave bands from 250Hz to 8000Hz. 7.11.3.3 The insertion loss of each cup shall be measured three times and the means value of the three measurements at each frequency shall be reported. 7.11.3.4 The means and standard deviation of the means values reported as described in 7.11.3.3, for cups to 20, shall be reported. 7.11.3.5 In the case of universal earmuffs the insertion loss shall be measured in only one mode, preferably over the head 7.11.4 Report Report for each frequency, and for each cup, the individual mean value of insertion loss, and for all cups the mean values, with standard deviation, as described in 7.11.3.3 and 7.11.3.4.

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7.12 Resistance to leakage 7.12.1 Principle Liquid filled cushions are subjected to force and examined for leakage. 7.12.2 7.12.2 Apparatus 7.12.2.1 Smooth steel plate, not less than 10 mm thick and of an area sufficient to accommodate the cushion when deformed. 7.12.2.2 Means for loading the cushion. 7.12.2.3 Procedure 7.12.3.1 Position the plate horizontally on a firm surface. 7.12.3.2 Place one of the cups on plate so that its cushion is in contact with the plate at all points around its periphery. 7.12.3.3 Apply vertical load of 28 N to the cup for 15 min ± min. 7.12.3.4 Remove the load and examine the cushion for leakage of liquid. 7.12.3.5 Repeat 7.12.3.2 to 7.12.3.4 with the other cup /cushion. 7.12.4 Report 7.13. Ignitability 7.13.1 Principle Steel rod is heated to unknown temperature and applied to earmuffs. 7.13.2 Apparatus 7. 13.2.1 Steel rod 300mm long and 6 mm diameter with flat ends. 7.13.2.2 Heat source. 7:13:2.3 Thermocouple temperature measuring device. 7.13.3 Procedure 7.13.3.3.1 Heat one end of the rod over a length of approximately 50 mm to temperature of 650°C ± 20°C and apply its heated end face against the surface of the ear-muffs with the force exerted by its own mass, for a period 5s ± 0.5 s. 7.13.3.3.2 Reheat the rod and repeat the test as many times as is necessary to access the behaviour of all exposed material in corporate in the ear-muffs. 7.13.4 Report Report if any part of the earmuffs ignites or continues to glow after removal of the rod. 7.14 Sound attenuation The sound attenuation of specimens numbered 1 to 4 shall be measured and presented in accordance with EN 24869 -1 (mean values and standards deviations). In the case of universal earmuffs sound attenuation values shall be provided for each intended mode of use.

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8. Information Information according with 8.1 and 8.2 shall be provided at least in the official language (s) of the Kenya. 8.1 Wearer information The following information for the wearer shall be supplied with earmuffs:

a) trade mark , or other means of identification, of manufacturer, importer or distributor b) model designation c) as appropriate the statement(s): i) This model of earmuff has satisfied the optional requirements at 50°C ii) This model of earmuffs has satisfied the optional requirements at -20°C. Note: These statements may be combined. d) description of the type of headband and of the cushions e) method of fitting/adjustments f) for small/large size range' ear-muffs as appropriate a warning on packaging box; “Small /large size range ear-muffs. Refer to wearer information”. g) For each mode of wearing, the following sounds attenuation values: 1) means value and standard deviation at each test frequency 2) APV ? value at each test frequency in accordance with ISO/DIS 4869-2 with the parameter a=1 3) H? , M ? and L ? value in accordance with ISO/DIS 4869-2 with the parameter a=1 4) SNR-value in accordance with ISO/DIS 4869-2 with the parameter a=1 Each set of values shall be given equal prominence. h) Recommendation that the wearer should ensure that: 1) the ear-muffs are fitted , adjusted and maintained in accordance with the

manufacturer's instructions. 2) the ear-muffs are worn at all times in noisy surroundings. 3) the ear -muffs are regularly inspected for serviceability i) a warning that , if the recommendations given in (i) above are not adhered to the protection afforded by the ear -muffs will be severely impaired j) Methods of cleaning and disinfecting which shall specify, and require the use of, cleaning agents that are known not to be harmful to the wearer. k) The statement ` This product may be adversely affected by certain chemicals substances. Further information should be sought from the manufacturer.' l) The statement Earmuffs and in particular cushions may deteriorate with use and should be examined at frequent intervals for cracking and leakag e, for example'. m) Recommended storage conditions before and after use.

n) The designation/reference and other information required when ordering replacement cushions.

KS 2093-1:2006

o) If appropriate, the method of cushions replacement p) The mass of the earmuffs q) The address from which additional information can be obtained 8.2 Additional information The following shall be available from the manufacturer on request: a) range of head sizes fitted b) information as specified in 8.1 c) results of tests performed in accordance with this standard. d) the name and country of the test laboratory, which performed the test, specified in 8.2(c) and the date of the tests. 9. Marking The earmuffs shall be durably marked with following information: a) the name, trade mark or other identification of the manufacturer b) model designation c) in the case of ear muffs intended by the manufacturer to be worn in a particular orientation, an

indication of the FRONT and /or TOP of the cups, and /or an indication of LEFT and RIGHT cup.

10. Workmanship and Finish The finished and assembled Earmuff shall have no any burrs on edges. All sharp corners shall be removed. The metallic headstrap for fastening over the head shall be smooth, free from seams, pits, die marks and rustproof.

11 . Sampling and acceptance criteria Sampling and acceptance criteria for badges shall be as given in the normative Annex A.

12. Packing Earmuffs shall be suitably packed in polyethylene envelopes to avoid scratching against each other before packing them in cartons. Each carton shall contain 100 Earmuffs.

KS 2093-1:2006

© KEBS 2006 – All rights reserved 21

ANNEX A (Normative)

Sampling Scheme and criteria for conformity for Ear-muffs A-1.1 Lot In any consignment, all the Earmuffs manufactured from same material under similar conditions of manufacturer, shall be grouped together to constitute a lot.

A-1.2 For ascertaining the conformity to this standard, samples of Earmuffs shall be selected and tested separately for each lot. A-1.3 The number of badges to be selected at random from a lot depending upon the size of the lot shall be in accordance with column 1 and 2 of table 3.

TABLE 3. Sample size and criteria for conformity for Earmuffs LOT SIZE (Number of Ear -muffs in a lot)

SAMPLE SIZE Number of Ear-muffs to be selected in a sample

PERMISSIBLE NUMBER OF DEFECTIVES

Upto 100 101-200 201 -300 301-400 401 –500 501 and above

4 8 12 16 20 40

0 1 2 3 3 5

A-1.4 The Ear-muffs shall be selected at random from the lot and in order to ensure randomness of selecti on, random number tables may be used. As a first step, suitable number of packages (not less than 10% of the total number in the lot subject to a minimum of 5) shall be chosen at random from each of the packages so chosen; an approximately equal number of Ear-muffs shall be picked at random so as to obtain the required number of Ear -muffs for the sample. In case random number tables are not available, the procedure given in A-1.4.1 may be adopted. A-1.4.1 Starting from any Ear-muff in the lot, count them as 1, 2,.3....up to r and so on order, where r is the integral part of N/n (N being the lot size and n being the number of Ear-muffs to be selected). Every r~" Ear-muff thus counted shall be withdrawn to gi ve sample for inspection. A-2 Number of tests and criteria for conformity A-2.1 The Ear-muffs selected in accordance with A-1.4.1 shall be examined. The lot shall be considered as conforming to the requirements of this standard if the number of Ear -muffs failing in any one or more of the requirements does not exceed the permissible number given in column 3 of table 3.

KS 2093-1:2006

ANNEX B (Informative)

List of standards referred to. 1. SO 4869-1:1990: Acoustics - Hearing protectors Part 1: Subjective method for the measurement of sound attenuation. 2. ISO 4869-2: 1994: Acoustics - Hearing protectors Part 2: Estimation of effective A-weighted sound pressure levels when hearing protectors are worn. 3. ISO/TR 4869-4: 1998: Acoustics - Hearing protectors Part 4: Measurement of effective sound pressure level-dependent sound restoration earmuffs. 4. EN 24869 -1: Hearing protectors - Mean values and standard deviations.