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1、| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | BRITISH STANDARD BS 7928:1998 ICS 13.340.2
2、0; 97.220.40 NO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAW Specification for head protectors for cricketers Licensed Copy: London South Bank University, London South Bank University, Fri Dec 08 10:40:20 GMT+00:00 2006, Uncontrolled Copy, (c) BSI This British Standard, having
3、 been prepared under the direction of the Sector Board for Health and Environment, was published under the authority of the Standards Board and comes into effect on 15 November 1998 BSI 1998 The following BSI references relate to the work on this standard: Committee reference PH/6 Draft for comment
4、97/540774 DC ISBN 0 580 29585 0 BS 7928:1998 Amendments issued since publication Amd. No.DateText affected Committees responsible for this British Standard The preparation of this British Standard was entrusted to Technical Committee PH/6, Head protection, upon which the following bodies were repres
5、ented: Headway National Head Injuries Association Health and Safety Executive Institution of Mechanical Engineers Royal National Life-Boat Institution Safety Equipment Association The following bodies were also represented in the drafting of the standard, through subcommittees and panels: British Sa
6、fety Industry Federation British Sports and Allied Industries Federation Consumer Policy Committee for BSI England and Wales Cricket Board Nottingham University SATRATechnology Centre Licensed Copy: London South Bank University, London South Bank University, Fri Dec 08 10:40:20 GMT+00:00 2006, Uncon
7、trolled Copy, (c) BSI BS 7928:1998 BSI 1998i Contents Page Committees responsibleInside front cover Forewordii Introduction1 1Scope1 2Normative references1 3Terms and definitions1 4Materials2 5Construction2 6Performance requirements3 7Impact attenuation test3 8Marking5 9Information to be supplied by
8、 the manufacturer6 Figure 1 Definition of helmet test area3 Figure 2 Principle of apparatus for determination of impact attenuation4 Table 1 Impact velocity for impact protection test5 Licensed Copy: London South Bank University, London South Bank University, Fri Dec 08 10:40:20 GMT+00:00 2006, Unco
9、ntrolled Copy, (c) BSI ii BSI 1998 BS 7928:1998 Foreword This British Standard has been prepared by Technical Committee PH/6. A British Standard does not purport to include all the necessary provisions of a contract. Users of British Standards are responsible for their correct application. Complianc
10、e with a British Standard does not of itself confer immunity from legal obligations. Summary of pages This document comprises a front cover, an inside front cover, pages i and ii, pages 1 to 6, an inside back cover and a back cover. Licensed Copy: London South Bank University, London South Bank Univ
11、ersity, Fri Dec 08 10:40:20 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BSI 19981 BS 7928:1998 Introduction The protection given by a helmet depends on the circumstances of the accident and wearing a helmet cannot always prevent death or long term disability. A proportion of the energy of an impact i
12、s absorbed by the helmet, thereby reducing the force of the blow sustained by the head. The structure of the helmet may be damaged in absorbing this energy and any helmet that sustains a severe blow needs to be replaced even if damage is not apparent. In preparing this standard the committee have be
13、en aware that no test exists for measurement of impact attenuation that simulates the impact of a moving cricket ball on a comparatively static helmeted player. The test method given records the impact of a moving helmeted headform on a hemispherical (simulated cricket ball shape) anvil, which is th
14、e nearest approximation to use among existing test methods. A 15 J impact was chosen for the impact attenuation test because: a) it is theoretically equivalent to a cricket ball speed of 25 m/s to 30 m/s; b) this impact enabled a distinction to be made between the protection levels offered by produc
15、ts currently manufactured. 1 Scope This British Standard defines the requirements for head protectors to be worn by cricketers. Requirements and the corresponding methods of test, where appropriate, are given for the following: a) construction; b) impact attenuation properties; c) marking and inform
16、ation to be supplied. 2 Normative references The following normative documents contain provisions which, through reference in this text, constitute provisions of this British Standard. For dated references, subsequent amendments to, or revisions of, any of these publications do not apply. For undate
17、d references, the latest edition of the publication referred to applies. BS EN 960:1995, Specification for headforms for use in the testing of protective helmets. BS AU 228-1:1989, Impact tests for road vehicles Part 1: Specification for measurement techniques and general instrumentation. 3 Terms an
18、d definitions For the purposes of this British Standard, the following terms and definitions apply. 3.1 head protector the complete assembly of helmet and faceguard 3.2 helmet headwear primarily intended to protect against a blow to the part of the wearers head that lies above the ears and eyes 3.3
19、faceguard an extension of, or an attachment to the shell, covering the face and ears, to give protection against impacts 3.4 shell the material that provides the general outer form of the helmet 3.5 padding 3.5.1 protective padding a material used to absorb impact energy 3.5.2 comfort padding a mate
20、rial provided for the wearers comfort 3.5.3 sizing padding a material used for adjustment of the helmet size 3.6 retention system the complete assembly that prevents inadvertent loss of the head protector 3.7 chin strap a strap that passes under the wearers chin or lower jaw and intended to prevent
21、inadvertent loss of the head protector 3.8 basic plane (of a human head) a plane at the level of the external auditory meatus (external ear opening) and the inferior margin of the orbit (lower edge of the eye socket) Licensed Copy: London South Bank University, London South Bank University, Fri Dec
22、08 10:40:20 GMT+00:00 2006, Uncontrolled Copy, (c) BSI 2 BSI 1998 BS 7928:1998 3.9 basic plane (of a headform) that plane relative to the headform that corresponds to the basic plane of the head that the headform simulates NOTEA precise position for the basic plane of a headform conforming to BS EN
23、960 is given in that standard. 3.10 central vertical axis the line relative to a headform conforming to BS EN 960 that lies in the plane of symmetry and normal to the reference plane at a point equidistant from the front and back of the headform in the reference plane 3.11 central longitudinal verti
24、cal plane the vertical plane of the symmetry of a human head or headform or of a helmet as it is intended to be worn on the head 3.12 size (of a helmet) the size of the head which the inner parts and retention system of the head protector are designed to fit NOTESeveral different sizes of helmet may
25、 be manufactured from one size of outer shell. 3.13 positioning index a dimension established by the manufacturer that defines the position in which the helmet is intended to be placed on the appropriate headform for testing purposes NOTE 1The index is equal to the vertical distance measured in the
26、central longitudinal vertical plane between the basic plane of the headform and the edge of the shell above the eyes NOTE 2This index should be furnished to any person who requests the information, with respect to a helmet identified by manufacturer, model designation and size. 3.14 peak an extensio
27、n from the basic form of the helmet above the eyes 4 Materials If the shell is made of any material which is known to be adversely affected by contact with hydrocarbons, cleaning fluids, paints, transfers or other extraneous additions, then the helmet shall carry an appropriate warning as specified
28、in 9.4. For those parts of the head protector coming into contact with skin, the material used shall be known not to undergo appreciable alteration from contact with sweat or from the substances likely to be found in toiletries. Materials which are known to cause skin disorders shall not be used. 5
29、Construction 5.1 Helmet The helmet shall cover areas of the head above the AA9 plane in accordance with Figure 1. There shall be no sharp edges on the inside of the helmet, and any rigid projections inwards shall be covered with protective padding. NOTE 1The helmet normally consists of a shell, not
30、necessarily of hard material, either containing or providing the necessary means of absorbing impact energy. NOTE 2Any irregularity in the internal or external surface should blend into the surrounding surface in a curve, the radius of which is not less than half the thickness of the shell at that p
31、oint. This recommendation need not be applied to holes for fasteners, or to the edges of the shell or to a rigid projection or peak in accordance with the above. NOTE 3The helmet may be pierced by ventilation holes. 5.2 Faceguards 5.2.1 General The faceguard shall be designed so that: a) it has no s
32、harp edges; b) it can be firmly fixed to the helmet for which it is designed, without the use of special tools, and without the need for the consumer to modify the helmet or faceguard; c) it permits the head protector to be readily removed in case of an accident. 5.2.2 Welded wire protectors All wir
33、e ends shall terminate on the outer perimeter of the head protector, away from the face. They shall not project beyond the perimeter of the faceguard, unless they are part of the attachment system. Welded joints shall be located so that a weld failure under stress is unlikely to cause injury to the
34、wearer. 5.2.3 Internal projections Rigid projections on the inside of the faceguard shall be limited to those required for ventilation or for attachment to the helmet or other accessories, and shall be no more than 3 mm in height. 5.2.4 Attachment systems The means of attaching the faceguard to the
35、helmet shall be specified by the manufacturer of the faceguard (see clause 9). 5.3 Retention system Means shall be provided for retaining the head protector on the wearers head. All parts of the retention system shall be permanently attached to the system or to the head protector. Any chin strap sha
36、ll be not less than 15 mm wide and not more than 26 mm wide and shall be elasticated or fitted with a fastening device to adjust and maintain tension in the strap. NOTEChin straps may be fitted with padding or other means of enhancing comfort for the wearer. Licensed Copy: London South Bank Universi
37、ty, London South Bank University, Fri Dec 08 10:40:20 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BSI 19983 BS 7928:1998 A A Figure 1 Definition of helmet test area 6 Performance requirements 6.1 General Head protectors shall be supplied for testing in the condition in which they are offered for sale
38、. Helmets incorporating systems for adjusting their size shall conform to each performance requirement when tested at the size which, in the opinion of the test house, is likely to give the poorest performance in that test. To demonstrate conformity one head protector of each size offered for sale,
39、with a minimum of six evenly distributed across the size range, shall be supplied for testing. Each head protector shall be subject to all necessary non-destructive tests and examinations before being subjected to any destructive test. A head protector that has been tested shall neither be offered f
40、or sale nor worn. 6.2 Impact attenuation When the head protector is tested by the method given in clause 7, the maximum deceleration of the striker shall not exceed 250 gn. NOTE 1The symbol gnsignifies a deceleration of 9.81 m/s2. NOTE 2Ideally, impact attenuation should be assessed using a cricket
41、ball moving at a speed simulating bowling in a match. This is currently impractical in a laboratory environment, however there is good theoretical correlation between a cricket ball impact at a speed of 25 m/s to 30 m/s and a 15 J impact based on the falling headform. 7 Impact attenuation test 7.1 H
42、elmet test area Take a full headform in accordance with BS EN 960:1994, sizes A, E, J, M or O. Place the head protector on the headform. Apply a vertical load of (505) N on the crown of the helmet in order to stabilize the helmet on the headform. Position the front edge of the helmet, using the manu
43、facturers positioning index if appropriate. If the positioning index is not specified, position the front edge of the helmet midway between the AA9 line on the headform and the reference plane. Draw the AA9 line (in the AA9 plane) on the helmet in accordance with Figure 1. 7.2 Faceguard adjustment A
44、djust the faceguard such that the gap between the faceguard and the edge of the helmet is as close as possible to, but without exceeding, 55 mm. Ensure the gap between the faceguard and the headform is as close as possible to, but not less than, 30 mm. NOTE When testing the faceguard, any parts of t
45、he faceguard and its attachment systems may be used as an impact site. 7.3 Conditioning 7.3.1 General Remove the head protector from the headform prior to conditioning. Licensed Copy: London South Bank University, London South Bank University, Fri Dec 08 10:40:20 GMT+00:00 2006, Uncontrolled Copy, (
46、c) BSI 4 BSI 1998 BS 7928:1998 Guides Support dolly Headform with helmet Hemispherical anvil Figure 2 Principle of apparatus for determination of impact attenuation 7.3.2 Ambient temperature Expose the head protector to a temperature of (205) 8C for a period of not less than 4 h. 7.3.3 High temperat
47、ure Place the head protector in a conditioning enclosure with effective circulation, so that it just touches the support on which it rests. Maintain the temperature in the enclosure at (502) 8C for a period of not less than 4 h and not more than 24 h. 7.3.4 Artificial ageing Expose the outer surface
48、 of the head protector to ultraviolet irradiation by a 125 W xenon-filled quartz lamp for (482) h at a range of 250 mm. 7.3.5 Number of samples Condition two or more head protectors for each of the three conditions given in 7.4.2 to 7.4.4; test at least six samples. NOTEThere is no need for further
49、conditioning prior to the second impact. 7.4 Apparatus 7.4.1 General The apparatus is shown in Figure 2 and shall comprise: a) a base; b) a steel anvil; c) a free fall guidance system; d) a mobile system supporting the helmeted head form; e) a metal headform conforming to BS EN 960, sizes A, E, J, M and O, and fitted with a tridirectional accelerometer; f) an accelerometer output recording and conditioning system; g) a system by which the point of impact can be brought into correspondence with the centre of the anvil. Licensed Copy: London South Bank University