DRAFT KENYA STANDARD                              DKS 77: 2012 
    ICS  
    
                         
 
 
 
 
 
 
 
 
 
 
 
Protective helmets for motorcyclists — 
Specification 
 
 
 
 
DRAFT KENYA STANDARD, APRIL 2012 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
©KEBS 2012        Second Edition 2012  
 DKS 77: 2012                                                                                                            
 
ii                     © KEBS 2012 — All rights res erved  
 
 
TECHNICAL COMMITTEE REPRESENTATION 
 
The following organizations were represented on the  Technical Committee: 
 
Automobile Association of Kenya 
Car and General Ltd. 
Consumer Information Network (C.I.N) 
General Motors (East Africa) Ltd. 
Kenya Auto Bazaar Association (K.A.B.A) 
Kenya Industrial Research and Development Institute  
Kenya Used Motor Parts Importers Association (K.U.M .P.I.A) 
Kenya Vehicle Manufacturers 
Ministry of Roads – Mechanical & Transport Departme nt 
Motor Vehicle Inspection Unit 
Mutsimoto Motor Co. Ltd. 
Nairobi Metropolitan PSV Saccos Union 
Kenya Bureau of Standards — Secretariat 
 
 
 
 
 
 
 
 
 
REVISION OF KENYA STANDARDS 
 
In order to keep abreast of progress in industry, K enya Standards shall be regularly reviewed. Suggest ions 
for improvements to published standards, addressed to the Managing Director, Kenya Bureau of Standards , 
are welcome. 
 
 
 
 
 
© Kenya Bureau of Standards, 2012 
  
Copyright. Users are reminded that by virtue of Sec tion 25 of the Copyright Act, Cap. 12 of 2001  of t he Laws of Kenya, copyright 
subsists in all Kenya Standards and except as provi ded under Section 26 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 with out prior permission in writing 
from the Managing Director. 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 DRAFT KENYA STANDARD                            DKS 77: 2012 
 ICS  
 
 © KEBS 2012 — All rights reserved           iii  
 
 
 
 
           
 
 
 
 
 
 
 
 
 
 
Protective helmets for motorcyclists — 
Specification 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
KENYA BUREAU OF STANDARDS (KEBS) 
 
Head Office:  P.O. Box 54974, Nairobi-00200, Tel.: (+254  020) 60 5490, 602350, Fax: (+254 020)  604031 
E-Mail: info@kebs.org,  Web:http://www.kebs.org   
 
Coast Region    Lake Region         Rift Valley Reg ion  
P.O. Box 99376, Mombasa-80100  P.O. Box 2949, Kisum u-40100       P.O. Box 2138, Nakuru-20100 
Tel.: (+254  041) 229563, 230939/40 Tel.: (+254 057 ) 23549, 22396       Tel.: (+254 051) 210553, 21055 5 
Fax: (+254  041) 229448   Fax: (+254 057) 21814         
 
 
 DKS 77: 2012                                                                                                            
 
iv                     © KEBS 2012 — All rights res erved Foreword 
 
This Kenya Standard was prepared by the Road Vehicl es Technical Committee under the guidance of the 
Standards Projects Committee, and it is in accordan ce with the procedures of the Kenya Bureau of 
Standards. 
 
Experience has shown that the effects of an impact can be considerably mitigated, within the limitatio ns 
stated, because an effective proportion of the ener gy of the impact is absorbed by a helmet:  The forc e of the 
blow which is transmitted to the head of the wearer  is thereby reduced. However, it should be apprecia ted 
that the protection given by a helmet cannot be abs olute regardless of the circumstances and the sever ity of 
an accident and that the use of a helmet cannot alw ays prevent death or long-term disability following  a 
severe accident.    Whilst absorbing energy the str ucture of the helmet may be damaged and any helmet 
which sustains a severe blow shall be replaced by a  new helmet even if damage is not apparent. 
 
Competition helmets are built to more stringent req uirements of other standards and some motorcyclists  may 
prefer the extra protection these offers even for e veryday use. 
 
This standard gives methods of test for the fundame ntal performance requirements and the minimum resul ts 
required from a satisfactory helmet. It sets out th e general principles of design whilst leaving the 
manufacturer as much freedom as possible in respect  of the materials used, the actual design and the 
methods employed to provide the required levels of protection. A helmet shall be as light in weight as  
possible both for the comfort of the wearer and to limit certain effects in the event of an accident a nd it is also 
very important that the helmet is a good fit.  
 
This standard has been revised to address the incre ased failures during the use of helmets and the 
prevalent non use of the helmets due to various fac tors such as discomfort, health concerns among othe rs 
as well as technological changes. 
 
This second edition cancels and replaces the 1978 e dition. 
 
The revision of this standard has been facilitated by World Health Organization (WHO) – Kenya under th e 
Road Safety 10 (RS10) project funded by Bloomberg P hilanthropies.  
 
In the preparation of this standard, reference was made to the following documents: 
 
UNECE R 22 Rev.4, Uniform provisions concerning the  approval of protective helmets and their visors fo r 
drivers and passengers of motor cycles and mopeds 
 
Global Helmet Vaccine Initiative (GHVI), Draft Stan dard Version 1.1, 14 November 2010, Draft specifica tion 
for protective helmets for motorcyclists 
 
IS 4151, Indian Standard, protective helmets for sc ooter and motorcycle riders 
  
Acknowledgement is hereby made for the assistance d erived from these sources. 
 
  
 DRAFT KENYA STANDARD                              D KS 77: 2012  
© KEBS 2009 — All rights reserved                     1  
 
 
 
Protective helmets for motorcyclists — Specificatio n 
 
 
1 Scope 
 
This Kenya Standard specifies the requirements for protective helmets intended for the protection of t he 
driver or of the rider and the pillion (passenger) while riding motorcycles of any kind, including mot orized 
bicycles/tricycles, mopeds, motorbikes, quad bikes and scooters with or without side-car. 
 
The standard does not apply to protective helmets i ntended to be used for competition riding. 
 
 
2 Normative references 
 
The following referenced documents are indispensabl e for the application of this Kenya Standard. For d ated 
references, only the edition cited applies. For und ated references, the latest edition of the referenc ed 
document (including any amendments) applies. 
 
EN 960, Headforms for use in the testing of protective helm ets 
 
ISO 6487, Road vehicles - Techniques of measurement in impact  tests - Instrumentation 
  
3 Definitions 
 
For the purposes of this Standard the following def initions shall apply: 
 
2.1 
motorcycle 
include motor bike, motorized bicycle/tricycles, mo ped, scooters, quad bikes. 
 
2.2 
protective helmet 
a device to be worn on the head intended to reduce the risk of head injury resulting from the impact w hile 
riding on a motorcycle and including 
a) a shock-attenuating system; 
b) the retention system; 
 
2.2 
shell (outer covering) 
the hard part of the protective helmet, which  give s it its general shape 
 
2.3  
protective padding 
a material used to absorb impact energy 
 
2.4 
comfort padding 
a material provided for the wearer's comfort 
 
2.5 
retention system 
the complete assembly by means of which the helmet is maintained in position on the head, including an y 
devices for adjustment of the system or to enhance the wearer's comfort 
 
2.5.1 
chin-strap 
a part of the retention system consisting of a stra p that passes under the wearer's jaws to keep the h elmet in DKS 77: 2012 
            
                              © KEBS 2012 — All rig hts reserved 2 position 
 
2.5.2 
chin-cup 
an accessory of the chin-strap that fits round the point of the wearer's chin 
 
2.6 
peak 
an extension of the shell above the eyes  
 
2.7 
lower face cover 
a detachable, movable or integral (permanently fixe d) part of the helmet covering the lower part of th e face; 
 
 
2.7.1 
protective lower face cover 
a detachable, movable or integral (permanently fixe d) part of the helmet covering the lower part of th e face 
and intended to protect the chin of the user agains t impacts 
 
2.7.2 
non protective lower face cover 
 a detachable or movable part of the helmet coverin g the lower part of the face that does not protect the chin 
of the user against impacts 
 
2.8 
visor 
a transparent protective screen extending over the eyes and covering all or part of the face 
 
2.9 
goggles 
transparent protectors that enclose the eyes 
 
2.10 
disposable protective film 
a removable plastic film that may be applied to pro tect the visor prior to use. The film has to be opa que or 
printed and is removed before use 
 
2.11 
ocular areas 
two circles of minimum diameter 52 mm spaced symmet rically about the vertical centre line of the visor , the 
distance between the centres of the circles being 6 4 mm measured in the horizontal front plane of the visor 
as worn 
 
2.12  
luminous transmittance “ τv" 
 is defined in annex C 
 
2.13 
relative visual attenuation quotient 
the relative visual quotient (Q) and is defined in annex C. 
  
 
2.14 
basic plane of the human head 
a plane at the level of the opening of the external  auditory meatus  (external ear opening) and the lo wer edge 
of the orbits (lower edge of the eye sockets) 
 
2.15 
basic plane of the head form 
a plane which corresponds to the basic plane of the  human head 
                            DKS 77: 2012 
 
 
© KEBS 2012 — All rights reserved         
     3
 2.16 
reference plane 
a construction plane parallel to the basic plane of  the head form at a distance from it which is a fun ction of 
the size of the head form 
 
2.17 
helmet positioning index (HPI) 
the vertical distance measured at the median plane,  from the front edge of the helmet to the basic pla ne, 
when the helmet is placed on the reference headform  
 
2.18 
horizontal plane  
plane that passes across the body at right angles t o both the frontal and median plane  
(See Figure 2) 
 
2.19 
maximum value of acceleration, a max  
highest point on the acceleration-time curve, encou ntered during impact, in units of g, 
 
2.20 
median plane 
vertical plane that passes through the headform fro m front to back and divides the headform into right  and 
left halves (See Figure 2). 
 
2.21 
“g” 
acceleration due to gravity ( 9.81m/s 2) 
 
Figure 1 – Helmet detail 
 
 
 DKS 77: 2012 
            
                              © KEBS 2012 — All rig hts reserved 4  
Horizontal plane
Median planeFrontal plane
 
 
Figure 2: Orientation planes 
 
 
4 Requirements 
 
4.1 General construction requirements 
 
4.1.1 The basic construction of the helmet shall be  in the form of a hard outer shell, containing addi tional 
means of absorbing impact energy, and a retention s ystem. 
  
4.1.2  No component or device may be fitted to or i ncorporated in the protective helmet unless it is 
designed in such a way that it will not cause injur y and that, when it is fitted to or incorporated in  the 
protective helmet, the helmet still complies with t he requirements of this Standard. 
 
4.1.3 The protective helmet may be fitted with ear flaps and a neck curtain. It may also have a detach able 
peak, and a lower face cover. If fitted with a non protective lower face cover the outer surface of th e cover 
shall be marked "Does not protect chin from impacts " and/or with the symbol shown in figure 1 below 
indicating the unsuitability of the lower face cove r to offer any protection against impacts to the ch in. 
  
 
Figure 1: Symbol "Does not protect chin from impact s 
 
4.1.4 The extent of the protection provided shall b e as follows: 
  
4.1.4.1  The shell shall cover all areas above plan e AA' and shall extend downwards at least as far as  the 
lines CDEF on both sides of the headform (Figure 3 A). 
                            DKS 77: 2012 
 
 
© KEBS 2012 — All rights reserved         
     5
  
 
Figure 3 – Minimum extent of protection 
 
 
4.1.4.2   At the rear, the rigid parts and, in part icular, the shell shall not be within a cylinder de fined as follows 
(see Figure 3 B): 
 
(i) Diameter 100 mm; 
(ii) Axis, situated at the intersection of the medi um plane of symmetry of the headform and of a plane  parallel 
to and 110 mm below the reference plane. 
 
4.1.4.3  The protective padding shall cover all the  areas defined in 4.1.4.1, account being taken of t he 
requirements of 4.1.4.4 
 
4.1.4.4  The helmet shall not dangerously affect th e wearer's ability to hear. The temperature in the space 
between the head and the shell shall not rise inord inately; to prevent this, ventilation holes may be provided 
in the shell. Where means for attaching a visor are  not provided, the profile at the front edge shall not prevent 
the wearing of goggles. 
 
4.1.3.5   All external projections shall be radiuse d and any external projections other than press-fas teners 
shall be smooth and adequately faired. 
 
4.1.3.6  All external projections not more than 2 m m above the outer surface of the shell (e.g. rivet heads) 
shall have a radius of a minimum of 1 mm. 
 
4.1.3.8  All external projections more than 2 mm ab ove the outer surface of the shell shall have a rad ius of a 
minimum of 2 mm. 
 
4.1.3.9  There shall be no inward-facing sharp edge s on the inside of the helmet; rigid, projecting in ternal 
parts shall be covered with padding so that any str esses transmitted to the head are not highly concen trated. 
 
4.1.3.10 The various components of the protective h elmet shall be so assembled that they are not liabl e to 
become easily detached as a result of an impact. DKS 77: 2012 
            
                              © KEBS 2012 — All rig hts reserved 6  
4.2 Construction material requirements 
 
4.2.1 All materials used shall be known not to be a dversely affected by ordinary household soap and 
cleaners as recommended by the manufacturer. Paints , glues and finishes used in manufacturing shall be  
compatible with the materials used in the construct ion of the helmet and shall not affect the mechanic al 
performance of the helmet according to the related tests in this Standard. 
 
4.2.2 The characteristics of the materials used in the manufacture of helmets shall be known not to un dergo 
appreciable alteration under the influence of agein g, or of the circumstances of use to which the helm et is 
normally subjected, such as exposure to sun, extrem es of temperature and rain. For those parts of the 
helmet coming into contact with the skin, the mater ials used shall be known not to undergo appreciable  
alteration through the effect of perspiration or of  toilet preparations. The manufacturer shall not us e materials 
known to cause skin irritations, diseases or troubl es. The suitability of a proposed new material shal l be 
established by the manufacturer. 
 
4.2.3 All materials used in the construction of the  helmet shall be resistant to irreversible polymeri c changes 
when exposed to temperatures from -10 oC to 50 oC.  
 
4.2.4 The weight of the helmet shall not exceed 196 0 g.  
 
4.2.5 After the performance of any one of the presc ribed tests, the protective helmet shall not exhibi t any 
breakage or deformation dangerous to the wearer.  
 
4.3 Resistance to external agent  
 
After each conditioning as described in 5.3, the he lmet shall be visually inspected. There shall be no  signs of 
cracking or appreciable distortion of the retro ref lective material. 
 
4.4  Retention system 
 
4.4.1  Retention systems shall be protected from ab rasion. 
 
4.4.2  The helmet shall be held in place on the wea rer's head by means of a retention system which is 
secured under the lower jaw. All parts of the reten tion system shall be permanently attached to the sy stem or 
to the helmet. 
 
4.4.3  If the retention system includes a chin-stra p, the strap shall be not less than 20 mm wide unde r a 
load of 150 ± 5 N. 
 
4.4.4  The chin strap may not include a chin-cup si nce the latter is integral with the shell. 
 
4.4.5  Chin straps shall be fitted with a device to  adjust and maintain tension in the strap. 
 
4.4.6  If a retention system includes a quick-relea se mechanism, then the method of release of this 
mechanism shall be self-evident.  Any levers, tabs, buttons or other components which  need to be operated 
to release the mechanism shall be coloured red, tho se parts of the rest of the system which are visibl e when 
closed shall not be similarly coloured, and the mod e of operation shall be permanently indicated. 
 
4.4.7 The buckle of the retention system shall be d esigned so as to preclude any possibility of incorr ect 
manipulation. It shall not be possible for the buck le to be left in a partially closed position. 
 
 
4.5 Test requirements 
 
4.5.1 Extent of protection  
 
The entire area of the helmet above the test line s tipulated in 5.5 shall attenuate impact energy to t he 
minimum requirements specified in 4.5.5.                            DKS 77: 2012 
 
 
© KEBS 2012 — All rights reserved         
     7
 4.5.2 Peripheral vision 
 
All helmets shall allow unobstructed vision through  a minimum of 105 o to the left and right sides of the 
median plane when measured in accordance with the p rocedures described in 5.7. 
4.5.3 Penetration resistance 
 
When tested in accordance with 5.8 at ambient tempe rature, no contact with the test headform by the te st 
dowel shall be made within any aperture on the helm et. 
 
4.5.4 Effectiveness of retention system 
 
When tested in accordance with 5.9, at ambient temp erature the helmet shall remain on the test headfor m. 
 
4.5.5 Strength of retention system 
 
When tested in accordance with 5.10, the retention system shall not detach and the maximum elongation of 
the retention system shall not exceed 25 mm when me asured between preliminary and test load positions.  
4.5.6 Sound attenuation 
 
When measured in accordance with 5.13, the sound dr op shall not be more that 10 dB. 
4.5.7 Rigidity 
 
When tested in accordance with 5.12:  
 
a) In the test along each axis, the deformation mea sured under the 630 N load shall not exceed that 
measured under the initial 30 N load by more than 4 0 mm. 
 
b) After restoration of the 30 N load, the deformat ion measured shall not exceed that measured under t he 
initial 30 N load by more than 15 mm. 
 
4.5.8 Shock absorption 
 
When the helmet is tested in accordance with 5.11,  the peak headform acceleration (a max ) shall not exceed 
275 g. 
 
 
4.5.9 Visors 
 
4.5.9.1 General requirements for visors 
 
4.5.9.1.1 The systems of attachment of a visor to a  helmet shall be such that the visor is removable. It must 
be possible to manoeuvre the visor out of the field  of vision with a simple movement of one hand. 
 
4.5.9.1.2 Visors shall be free from any significant  defects likely to impair the vision, such as bubbl es, 
scratches, inclusions, dull spots, holes, mould mar ks, scratches or other defects originating from the  
manufacturing process in the field of vision.  
 
4.5.9.1.3 Visors shall in addition be sufficiently transparent, shall not cause any noticeable distort ion of object 
as seen through the visor, shall be resistant to ab rasion, not easily broken and shall not give rise t o any 
confusion between the colour used in road traffic s ign and signals. 
 
 
 DKS 77: 2012 
            
                              © KEBS 2012 — All rig hts reserved 8 4.5.9.2 Test requirements for visors 
  
4.5.9.2.1 Field of vision 
 
4.5.9.2.1.1 The visor shall not comprise any part l iable to impair the user's peripheral vision as def ined 
in 4.5.2 when the visor is in the totally opened po sition. 
  
4.5.9.2.1.2 The field of vision of the visor shall be: 
 
(a) A dihedron defined by the reference plane of th e headform and a plane forming an angle of at least  7° 
upwards, its edge being the straight line L1 L2, wi th points L1 and L2 representing the eyes, 
 
(b) Two segments of dihedral angles symmetrical to the median vertical longitudinal plane of the headf orm. 
Each of these dihedral angles is defined by the med ian vertical longitudinal plane of the headform and  the 
vertical plane forming with this plane an angle of 90°, its edge being the straight line LK, 
 
(c) and the lower edge of the visor. 
 
4.5.9.2.1.3 To determine the field of vision as def ined in 4.5.9.2.1.2 above, the helmet fitted with t he visor 
being tested shall be placed on a test headform of suitable size with the helmet tipped towards the re ar and 
the visor placed in the closed position. 
 
4.5.9.2.2 Luminous transmittance 
 
Visors shall have a luminous transmittance τv 80%, relative to the standard illuminant D65 when  measured in 
accordance with Annex B 
  
4.5.9.2.3 Light diffusion 
 
The light diffusion shall not exceed the limit in t able 1 when measured accordance with 5.14.2.1.2 usi ng one of the 
methods specified in annex B 
  
 
Table 1 — Light diffusion limits  
 
 
a/ measured according to annex B, method (a);  
b/ measured according to annex B, method (b); 
c/ measured according to annex B, method (c). 
 
 
If different results arise when this is assessed, t he requirements on scattered light shall be measure d and 
assessed over an area 5 mm in diameter which includ es the presumed error. In addition, the regular tra nsmittance 
shall not deviate by more than 5 per cent from the reference value, measured in one of two sight point s specified 
in 4.5.9.3.6, at any point within the field of visi on of the visor.  
  
4.5.9.2.4 Reception of signal lights 
 
The relative attenuation quotient shall be measured  by the method given in 5.14.2.1.1 , before the abrasion 
test. The relative visual attenuation quotient (Q) shall not be less than: 
 
0.80 for red and yellow signal lights; 
0.60 for green signal light; 
0.40 for blue signal light. 
  
 
 
                            DKS 77: 2012 
 
 
© KEBS 2012 — All rights reserved         
     9
 4.5.9.2.5 Spectral transmittance 
 
In the range 500 nm to 650 nm, the spectral transmi ttance, measured by the method given in 5.14.2.1.1,  
shall not be less than 0.2 τv. The spectral transmittance shall be measured bef ore the abrasion test. 
 
4.5.9.2.6 Refractive powers 
 
The table contains the permissible refractive power s at the sight points. The sight points are located  in the 
reference plane 32 mm to the right and the left of the longitudinal median plane (see Figure 2). 
 
 
 
Permissible refractive power values for visors 
 
D1, D2: Refractive effect in two main sectors  
The requirements for the prismatic effect apply to the difference between the values at the two sight points. 
The refractive powers shall be measured according t o method specified in annex E.  
 
 
4.5.9.2.7 Mist retardance 
 
The internal face of the visor is regarded as havin g a mist retardant facility if the square of the sp ecular 
transmittance has not fallen below 80 per cent of t he initial value without misting within 20 s when t ested in 
accordance with annex F. Such facility may be indic ated by the English words “MIST RETARDANT”.  
 
4.5.9.2.8 Mechanical properties 
 
When tested in accordance with 5.14.1.3.3, the test  piece shall then be subjected to the abrasion test  
described in annex A, during which 3 kg of abrasive  material shall be projected at the sample. 
 
 
4.5.9.2.9 Optical quality and  scratch resistance 
 
When tested in accordance with annex B , visors shall have a luminous transmittance Ʈv 80%, relative to 
the standard illuminant D65. 
 
 
5 Test methods 
 
5.1   General  
 
Helmets shall be capable of meeting the requirement s in this Standard throughout their full range of a vailable 
sizes. Each helmet shall be tested on the headform size of best fit. All testing shall be done with th e visor 
and all accessories removed (if applicable). DKS 77: 2012 
            
                              © KEBS 2012 — All rig hts reserved 10  
 
5.2  Samples for testing  
  
In order to determine whether a lot of protective h elmets containing up to 500 helmets of one class, t ype, 
size and origin, complies with the standard, a samp le of 6 helmets shall be taken at random from the l ot and 
tested as per the test schedule specified in 5.6. 
 
 
5.3  Conditioning environments 
 
Helmets shall be conditioned to one of the followin g environments prior to testing in accordance with the test 
schedule specified in 5.6.  All test helmets shall be stabilized within the ambient condition for 4 to  6 hours 
prior to further conditioning and testing.  
 
5.3.1 Ambient conditioning 
 
The sample shall be exposed to a temperature of 23 ± 5˚C and a relative humidity not exceeding 75 % fo r 4 
to 6 hours. 
 
5.3.2 Low temperature conditioning 
 
The sample shall be exposed to a temperature of -10 ± 3˚C for 4 to 6 hours. Testing shall begin within 60 s of 
removal from the low temperature conditioning chamb er. Complete all helmet testing within 5 minutes af ter 
removal from the conditioning environment. Helmets may be returned to the conditioning environment in 
order to meet this requirement. Helmets shall remai n in the conditioning environment for 15 minutes fo r each 
5 minutes that they are out of the conditioning env ironment. 
 
5.3.3 Elevated temperature conditioning 
  
The sample shall be exposed to a temperature of 50 ± 2˚C for 4 to 6 hours. Testing shall begin within 60 s of 
removal from the elevated temperature conditioning chamber. Complete all helmet testing within 5 minut es 
after removal from the conditioning environment. He lmets may be returned to the conditioning environme nt in 
order to meet this requirement. Helmets shall remai n in the conditioning environment for 15 minutes fo r each 
5 minutes that they are out of the conditioning env ironment. 
 
5.4  Test headforms 
 
A headform, capable of accepting an accelerometer m ounted at its centre of gravity and conforming to t he 
requirements of a three quarter headform as defined  in EN 960, shall be used. Headforms used for impac t 
testing shall be rigid and be constructed of low re sonance K–1A magnesium alloy. The headform and 
supporting assembly shall have a total combined mas s as described in the following table, with the 
supporting assembly contributing to no more than 25 % of the total mass. 
Table1 — Test headforms 
Headform label Size 
Designation Mass 
A 495 mm 3.10 kg ± 0.10 kg 
E 535mm 4.10 kg ±0.12 kg 
J 575mm 4.70 kg ±0.14 kg 
M 605mm 5.60 kg ±0.16 kg 
O 625mm 6.10 kg ±0.18 kg 
 
                            DKS 77: 2012 
 
 
© KEBS 2012 — All rights reserved         
     11 
 5.5 Marking the test line 
  
A reference headform that is firmly seated with the  basic plane horizontal shall be used for reference  
marking. The complete helmet to be tested shall be placed on the applicable reference headform whose 
circumference is not greater than the internal circ umference of the headband when adjusted to its larg est 
setting, or, if no headband is provided, to the cor responding interior surface of the helmet. 
 
The helmet shall be positioned on the reference hea dform and a static force of 50 N shall be applied n ormal 
to the apex of the helmet. The helmet shall be cent red laterally and seated firmly on the applicable r eference 
headform according to its helmet positioning index (HPI). If the HPI and corresponding headform size a re not 
available from the manufacturer, the test technicia n shall choose the headform and HPI value. Maintain ing 
the force and position described above, a test line  shall be drawn on the outer surface of the helmet 
coinciding with that on the headform as shown in Fi gure 4. 
 
 
  
Headform Label Dimensions (mm) 
a b c d e f g 
A (495 mm) 23 65 88 59 34.5 26.5 113.5 
E (535 mm) 29.5 65 94.5 64 39 33 122 
J (575 mm) 36 65 101 66 41 36 130 
M (605 mm) 41 65 106 67 41.5 37 136 
O (625 mm) 43.5 65 108.5 68 42 38 140 
 
Figure 4 — Extent of protection and test lines 
 
5.6  Test schedule  
 
5.6.1 Helmet samples shall be tested according to t he test schedule shown in Table 2. The sequence of 
testing shall be as follows: 
 DKS 77: 2012 
            
                              © KEBS 2012 — All rig hts reserved 12 1. Peripheral vision test (if applicable) 
2. Penetration resistance test (if applicable) 
3. Effectiveness of retention system test (if appli cable) 
4. Strength of retention system test 
5. Shock absorption test 
6. Sound attenuation test 
7. Rigidity test 
 
  
Table 2 — Helmet test schedule 
Sample Peripheral 
vision 
test Penetration 
resistance 
test Effectiveness 
of retention 
system test Strength 
of 
retention 
system 
test Shock 
absorption 
test Sound 
attenuation 
test Rigidity 
test 
Helmet 1 – 
Ambient 
Temperature  X X  X X   
Helmet 2 – 
Low 
Temperature     X X   
Helmet 3 – 
Elevated 
Temperature     X X   
Helmet 4 – 
Water 
Immersion    X X   
Helmet 5 – 
Ambient 
Temperature    X   X X 
 
 
5.6.2   Visor samples shall be tested according to the test schedule shown in Table 3. 
 
 
Table 3 — Visor test schedule 
 
Sample  Field 
of 
vision  Luminous  
Transmittance,  
Light diffusion,  
Recognition of signal 
lights, Spectral 
transmittance Refractive 
powers Mist 
retardant 
visor 
 Mechanical  
characteristics  Optical 
quality 
and 
scratch 
resistance 
Visor 1 x x    x 
Visor 2   x  x  
Visor 3   x  x  
Visor 4    x   
Visor 5  x    x 
  
  
5.7 Peripheral vision test                            DKS 77: 2012 
 
 
© KEBS 2012 — All rights reserved         
     13 
  
Position the helmet on a reference headform in acco rdance with the HPI and place a 50N preload ballast  on 
top of the helmet to set the comfort or fit padding . (Note:  peripheral vision clearance may be determined 
when the helmet is positioned for marking the test lines). Peripheral vision is measured horizontally from 
each side of the median plane around the point K (s ee Figure 5). Point K is located on the front surfa ce of 
the reference headform at the intersection of the b asic and median planes. The vision shall not be obs tructed 
within 105 degrees from point K on each side of the  median plane. Measurement may be performed with a 
physical measuring device (i.e. peripheral vision t emplate or a test headform with point K clearly mar ked) or 
with laser measurement equipment. 
  
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Figure 4: Peripheral vision test 
 
 
 
 
Figure 5 — Peripheral vision test 
 
 
5.8  Penetration resistance test 
 
5.8.1   Apparatus 
 
The apparatus for the penetration test shall includ e a full size reference headform that meets the 
requirements of EN 960:2006. 
 
5.8.2  Method 
  
Position the helmet on a reference headform in acco rdance with the HPI and place a 50N preload ballast  on 
top of the helmet to set the comfort or fit padding . Using a metal test dowel with a diameter of 20mm (see 
Figure 6) attempt to make contact with the headform  by trying to enter any part of the metal dowel end  
through all of the openings of the helmet. Record t he location of any metal dowel to headform contact.  
  
 
DKS 77: 2012 
            
                              © KEBS 2012 — All rig hts reserved 14 
 
Figure 6 — Metal Dowel for Penetration Test 
 
 
5.9  Retention system effectiveness test 
 
5.9.1 Apparatus 
 
The apparatus for the retention system effectivenes s test shall include a full size reference headform  that 
meets the requirements of EN960:2006.  
 
5.9.2  Method 
 
Secure the reference headform to a fixture that wil l prevent headform movement when a tangential force  is 
applied to the helmet. Position the helmet on a ref erence headform in accordance with the manufacturer ’s 
instructions. A flexible strap and hook mechanism s hall be attached to the front lower edge of the hel met 
such that it is in line with the mid-sagittal plane . The total mass of the falling weight guide appara tus shall be 
3 ± 0.1 kg and shall be able to accommodate drop he ights up to 100 cm. A 10 ± 0.1 kg drop weight shall  then 
be raised to a height of 50 cm ± 0.5 cm and release d (see Figure 7). 
 
This procedure shall be repeated with the hook mech anism attached to the rear edge of the helmet. 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
                            DKS 77: 2012 
 
 
© KEBS 2012 — All rights reserved         
     15 
  
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Figure 6: Typical retention system effectiveness te st apparatus 
 
 
 
 
 
 
 
 
 
 
 
Figure 7 — Typical retention system effectiveness t est apparatus 
 
 
5.10 Retention system strength test 
 
5.10.1  Apparatus 
 
Retention system strength test device consists of b oth an adjustable loading mechanism by which a stat ic 
tensile load is applied to the helmet retention ass embly and a means for holding the test headform and  
helmet stationary. The retention system test device  shall allow the retention assembly to be fastened around 
two freely moving rollers, both of which have a 12. 5 mm diameter and a 75 mm centre-to-centre separati on, 
and which are mounted on the adjustable portion of the tensile loading device (see Figure 8).  
 
 
 
 
 
 
 
 
 
 
 
 
 
 
DKS 77: 2012 
            
                              © KEBS 2012 — All rig hts reserved 16 
 
 
Figure 8: Typical retention system strength test ap paratus 
 
5.10.2   Method 
 
Place the subject helmet on the test headform such that the basic plane is normal to the force of grav ity and 
adjust it in accordance with the manufacturer’s HPI . Securely fasten the retention system around the t wo 
freely moving rollers in a manner that avoids conta ct between the rollers and helmet’s buckle. Apply a  
preliminary load of 45 ± 3 N in the direction norma l to the basic plane to the retention system and ho ld for a 
minimum of 30 seconds. Record the displacement meas urement on the moveable test device. Increase the 
load to 500 ± 5 N and maintain this load for 120 se conds, + 0 seconds, - 10 seconds by adjusting the l oad 
applied to the retention system as necessary. After  120 seconds (+0 seconds, -10 seconds) at full test  load, 
measure and record the displacement measurement of the retention system. The maximum elongation shall 
be the difference between the initial measurement a nd the measurement taken after 120 seconds. 
 
 
5.11    Shock absorption test 
 
5.11.1  Apparatus 
 
The test apparatus for the shock absorption test sh all consist of the following: 
 
(a) The headform employed in this test shall confor m to all requirements under 5.4.  
 
(b) The test headform shall be mounted on a guided freefall system as shown in Figure 8 with an adjust able 
mounting for the helmeted headform to permit impact s to be delivered to any location on the helmet at 
or above the test line. A monorail guided freefall system shall also be acceptable. The total mass of this 
support assembly shall not exceed 25% of the combin ed mass of the drop assembly (i.e., supporting 
assembly plus the test head-form). The centre of gr avity of the drop-assembly unit shall lie within a cone 
having a vertical axis and forming at most a 10 deg ree included angle with the vertex as the point of 
impact.  
 
 
                            DKS 77: 2012 
 
 
© KEBS 2012 — All rights reserved         
     17 
  
Figure 9 — Typical drop assembly apparatus 
 
 (c) A linear accelerometer shall be placed at the centre of gravity of the test head-form and its sen sitive 
axis shall be aligned to within 5 degrees of the ve rtical when the helmet and headform are in the impa ct 
position. The accelerometer shall be capable of wit hstanding a maximum acceleration of 1000 g without 
damage and shall have a frequency response of at le ast 5 to 900 Hz. A triaxial accelerometer with 
identical performance specifications is also accept able. 
 
(d) The flat anvil shall be made of steel or anothe r similar rigid metal and shall be firmly attached to the 
base of the drop assembly. The impact face shall ha ve a minimum diameter of 150 mm. 
 
(e) The hemispherical anvil shall be made of steel or another similar rigid metal and shall be firmly attached 
to the base of the drop assembly. The hemispherical  anvil shall have a hemispherical impact surface 
with a radius of 48 ± 1 mm. 
 
(f) The rigid mount for the anvils shall consist of  a solid mass of at least 135 kg, the upper surface  of which 
shall consist of a steel plate with a minimum thick ness of 12 mm and minimum surface area of 0.1 m2
. 
 
(g) The data acquisition system shall be capable of  collecting impact data at a rate of not less than 10 kHz 
per channel. The measuring system, including the dr op assembly, shall have a frequency response in 
accordance with channel frequency class (CFC) 1000 of ISO 6487. 
 
 
 
5.11.2  System verification 
 
The shock absorption test instrumentation shall be verified before and after each series of tests (at least at 
the beginning and end of each test day) by dropping  a spherical impactor onto a modular elastomer 
programmer (MEP) test surface.  
  
The spherical impactor shall be a device made of lo w resonance material (for example, magnesium), 
aluminum alloy, or stainless steel that couples mec hanically with the ball arm connector of the drop a ssembly 
DKS 77: 2012 
            
                              © KEBS 2012 — All rig hts reserved 18 in place of the impact test headform. When mounted,  the device presents a spherically machined impact 
face with a radius of 73 mm on its bottom surface. All radii from the center of the curvature of the i mpact face 
to its outer edge shall form angles of no less than  40° with the downward vertical axis. The center of  
curvature shall be within 5 mm of the vertical axis  drawn through the center of the ball arm. The tota l mass of 
the spherical impactor drop assembly shall be 5.0 ±  0.1 kg.  
 
The MEP shall be 152 mm in diameter and 25 mm thick , and shall have a durometer of 60 ± 2 Shore A. The  
MEP shall be affixed to the top surface of a flat 6 .35 mm thick aluminum plate. The geometric center o f the 
MEP pad shall be aligned with the center vertical a xis of the accelerometer.  
 
The impactor shall be dropped onto the MEP at an im pact velocity of 5.44 m/s ± 2% as measured within t he 
last 40mm of free fall of the impactor. Typically, this requires a minimum drop height of 1.50 metres plus a 
height adjustment to account for friction losses. S ix impacts, at intervals of 75 ± 15 seconds, shall be 
performed at the beginning and end of the test seri es (at a minimum at the beginning and end of each t est 
day). The first three of six impacts shall be consi dered warm-up drops, and their impact values shall be 
discarded from the series. The second three impacts  shall be recorded. All recorded impacts shall fall  within 
the range of 380 g to 425 g. The mean of the 3 post -test results shall not differ by more than 5% from  the 
mean of the pre-test results. Otherwise, the result s shall be discarded and the tests repeated with ne w 
samples after the source of this difference has bee n rectified.  
 
The components of the data acquisition system, incl uding all transducers shall be calibrated to tracea ble 
national reference standards at an interval of not greater than five years. 
 
5.11.3 Helmet impact test locations 
 
Each helmet shall be tested at four impact location s on or above the test line described in Clause 5.3 . Each 
impact location shall be a distance of at least one -fifth of the circumference of the test headform fr om any 
prior impact location on that helmet.  
 
5.11.4  Method 
 
5.11.4.1 The helmet shall be placed on the appropri ate headform according to the manufacturer’s helmet  
positioning index (HPI). The helmet shall be droppe d onto the flat anvil with an impact velocity of 6. 0 m/s ± 
3%. Typically, this requires a minimum drop height of 1.83 metres, plus a height adjustment to account  for 
friction losses.  
 
The helmet shall be dropped onto the hemispherical anvil with an impact velocity of 5.2 m/s ± 3%. Typi cally, 
this requires a minimum drop height of 1.38 metres,  plus a height adjustment to account for friction l osses. 
The impact velocity shall be measured during the la st 25 mm of free-fall for each test. Following impa ct, the 
drop assembly shall be raised and the headform shal l be oriented to another impact site.  
 
5.9.4.2 The first impact shall be made not more tha n 60 s after the helmet has been removed from the 
conditioning environment. Following testing, the he lmet shall be immediately returned to its condition ing 
environment for a minimum of 15 min before another impact test is conducted. 
 
5.12 Rigidity test 
 
The helmet, after undergoing ambient-temperature an d hygrometry conditioning, shall be placed between 
two parallel plates by means of which a known load can be applied along the longitudinal axis 6/ (line  LL in 
the Figure 10) or the transverse axis (line TT in t he figure). The surface of the plates shall be larg e enough to 
contain a circle of at least 65 mm in diameter. An initial load of 30 N shall be applied, at a minimum  plates 
speed of 20 mm/min, and after two minutes the dista nce between the two plates shall be measured. The 
load shall then be increased by 100 N, at a minimum  plates speed of 20 mm/min, and then wait for two 
minutes. This procedure shall be repeated until the  application of a load of 630 N. 
                            DKS 77: 2012 
 
 
© KEBS 2012 — All rights reserved         
     19 
 
 
Figure 10 — Rigidity test axes 
 
The load applied to the plates shall be reduced to 30 N, at a minimum plates speed of 20 mm/min; the 
distance between the plates shall then be measured.  
 
5.12.3. The helmet used for the test along the long itudinal axis shall be a new helmet, and another ne w 
helmet shall be used for the test along the transve rse axis. 
 
 
 
5.13  Sound attenuation test 
 
The sound test is done with a meter mounted inside a helmeted headform at the left or the right ear lo cation. 
The location should be uninterrupted for 12 m radiu s without any acoustic materials, as in open ground . A 
horn is sounded (90-115 dB, ambient sound should be  10 dB or less) 2 metres from the helmet, mounted 
rigidly 1.2 m off the ground on a stand. The sound level is measured at the sound meter location with and 
without the helmet covering it.  
 
 
5.14   Visor tests 
 
5.14.1. Test procedure 
 
5.14.1.1 The test piece shall be taken from the fla ttest part of the visor in the area specified in 4. 5.9.2.1.2 and 
its minimum dimensions shall be 50 mm x 50 mm. The test shall be carried out on the face corresponding  to 
the outside of the visor. 
 
5.14.1.2 The test piece shall undergo ambient-tempe rature and hygrometry conditioning in accordance wi th 
5.3. 
 
5.14.1.3 The test shall comprise the following sequ ence of operations: 
 
5.14.1.3.1 The surface of the test piece shall be w ashed in water containing 1 per cent detergent and rinsed 
with distilled or demineralised water, then careful ly dried with a grease-free and dust-free linen clo th. 
 
5.14.1.3.2 Immediately after drying and before abra sion, the luminous transmittance shall be measured using 
the method given in 5.14.2.1.1., and the light diff usion shall be measured according to one of the met hods 
specified in annex B. 
 
5.14.1.3.3 The test piece shall then be subjected t o the abrasion test described in annex A, during wh ich 3 
kg of abrasive material shall be projected at the s ample. 
 DKS 77: 2012 
            
                              © KEBS 2012 — All rig hts reserved 20 5.14.1.3.4 Following the test, the test piece shall  again be cleaned in accordance with 5.14.1.3.1 
  
5.14.1.3.5 Immediately after drying the light diffu sion after abrasion shall be measured by using agai n the 
same method used in accordance with 5.14.1.3.2 abov e. 
 
5.14.2  Requirements 
 
5.14.2.1. Three similar test pieces, each from a di fferent visor and taken from the area specified in 
4.5.9.2.1.2, shall meet the requirements of 5.14.2. 1.1 and 5.14.2.1.2. 
 
5.14.2.1.1 In a parallel beam, with the test specim ens being irradiated vertically, determine the spec tral 
transmittance values between 380 nm and 780 nm and then the transmittance and the visual attenuation 
quotient in accordance with the equations given in annex C. 
 
To calculate the luminous transmittance, the spectr al distribution of standard illuminant D65 and the spectral 
values of the colorimetric 2° standard observer CIE  1931 according to ISO/CIE 10526 shall be used. The  
product of the spectral distribution of standard il luminant D65 and the spectral values of the colorim etric 2° 
standard observer CIE 1931 according to ISO/CIE 105 26 is given in annex D. Linear interpolation of the se 
values for steps smaller than 10 nm is permissible.  
 
The light diffusion shall not exceed the following values for each method: 
 
 
6 Acceptance and rejection criteria 
 
Owing to the fact that the destructive nature of pa rt of the tests detailed in the standard does not a llow the 
performance of all the tests on  a single helmet, i t is not possible by testing a single helmet to det ermine its 
compliance with the standard.  Shall any of the fiv e sample helmets fail to comply with the relevant 
requirement of the standard, then the entire lot sh all be rejected as not complying with the standard.  
 
 
7 Labelling, Warnings and Instructions 
 
7.1   Labelling 
 
7.1.1  Helmet markings 
 
Every helmet shall have indelibly printed on it or otherwise permanently affixed to it, the following 
information, clearly and prominently displayed in n o less than 8 point font: 
(a) the name of the manufacturer; 
(b) website address of the manufacturer or other co ntact information; 
(c) the model name or model number of the product; 
(d) the size or size range of the circumference of the helmet, quoted as the circumference (in 
centimeters) of the head which the helmet is intend ed to fit; and 
(e) the week, year of manufacture of the product 
 
(f)  the words, “intended for motorcycle riders” an d “fasten the chin strap” 
 
7.1.2 Packaging 
 
The packaging in which the helmet is sold or is to be sold shall have indelibly printed on it or other wise 
permanently affixed to it, clearly and prominently displayed, the information required by section 7.1. 1. 
 
 
7.2    Warnings 
 
Every product shall have indelibly printed on it or  otherwise permanently affixed to it the following information 
statements, clearly and prominently displayed: 
 
(a) Words to the following effect: For adequate pro tection this helmet must fit closely. Purchasers ar e 
advised to secure the helmet and to ensure that it cannot be pulled or rolled off the head.                            DKS 77: 2012 
 
 
© KEBS 2012 — All rights reserved         
     21 
  
(b) Words to the following effect: This helmet is m ade to absorb some of the energy of a blow by parti al 
destruction of its component parts and, even though  damage may not be apparent, any helmet which 
has suffered an impact to the head in an accident o r received a similar severe blow or other abuse 
should be replaced. 
(c) Words to the following effect: To maintain the full efficiency of this helmet there must be no alt eration 
to the structure of the helmet or its component par ts. 
(d) For helmets fitted with a single chin strap, wo rds to the following effect: The chin strap must pa ss 
underneath the jaw to maintain tension all the time  the helmet is in use. The law requires that the 
helmet be securely fastened to the head. 
(e) Words to the following effect: The protection g iven by this helmet may be severely reduced by the 
application of paint, adhesive stickers and transfe rs, cleaning fluids and other solvents. Use only 
materials recommended by the helmet manufacturer. 
 
7.3   Instructions 
 
Every product shall bear or be accompanied by legib le written instructions that clearly state the foll owing 
information, with line drawings or photographs illu strating the sequence of steps where needed: 
(a) how the product is to be fitted and adjusted pr operly; 
(b) how the product is to be assembled, if applicab le 
(c) how the product should be inspected for deficie ncies; 
(d)  how the product is to be maintained, cleaned a nd dried; and 
(e) how the product is to be stored. 
  
 
8  Test Report 
 
The test report shall include at least the followin g information: 
 
(a) the number and year of publication of this Stan dard;  
(b) the name or trademark of the manufacturer or th e body taking responsibility for manufacture; 
(c) identification details of the protective helmet  tested as specified in clause 7.1.1. 
(d) illustrations of the front and side of the helm et; a test line should be drawn on the illustration . 
(e) results of tests in accordance with Clause 5, i ncluding information to clearly identify the impact  test 
locations for each helmet tested; 
(f) any evidence that shows conformity with require ments in clause 4 and 5; 
(g) date of testing;  
(h) name of technician who performed the testing an d if applicable, the laboratory manager or supervis or, 
and; 
(i) name of testing laboratory. 
 
 
 
 
 
 
 
 
 
 DKS 77: 2012 
            
                              © KEBS 2012 — All rig hts reserved 22  
Annex A 
(normative) 
Abrasion test procedure 
 
A.1 Description of the test equipment 
 
The sand spray test equipment consists essentially of that illustrated in Figure A.1. The gravity tube  consists 
of three separate rigid polyvinylchloride tubes (PV C hard) of the same diameter, with two polyamide si eves 
mounted in between. The sieves should have a mesh s ize of 1.6 mm. The speed of the turntable shall be 
250 + 10 rpm. 
 
A.2  Abrasive material 
 
Natural quartz sand of a grain size of 0.50/0.7 mm,  with no oversize, obtained by sieving on wire siev es 
complying with ISO 565 with a mesh size of 0.50 mm and 0.7 mm. The sand may be used up to 10 times. 
 
A.3 Test procedure 
 
Three kilograms of 0.50/0.7 mm grain size quartz sa nd is allowed to drop through a gravity tube from a  
height of 1,650 mm onto the sample to be tested. Th e test piece and, if necessary, a control-piece are  
mounted on a turntable, the axis of which is at a 4 5° angle to the direction of the sand. 
 
The test pieces are mounted on the turntable in suc h a way that the area to be measured does not exten d 
beyond the turntable. Whilst the turntable is rotat ing, 3 kg of sand are allowed to spray over the tes t pieces. 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
                           DKS 77: 2012 
 
 
© KEBS 2012 — All rights reserved         
     23 
  
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1. Parts of gravity tube 
2. Container with discharge jet as figure 2, contai ning at least 3 kg sand 
3. Upper sieve 
4. Lower sieve 
5. Test piece 
6. Test piece holder (turnable) 
 
Figure A.1 — Sand spray equipment 
 
 
 
 
 
 
 
 
 
 DKS 77: 2012 
            
                              © KEBS 2012 — All rig hts reserved 24  
Annex B 
(normative) 
Methods of measuring light diffusion and light tran smission coefficient 
 
B.1  Method (a)  
 
 
B1.1  Equipment 
 
 
 
 
 
This assembly collects all the unscattered light or iginating from the visor up to an angle of 0.72 deg ree (using 
diaphragm B L) and all scattered light between the angles 1.5 de grees and 2 degrees in relation to the optical 
axis using diaphragm B R. The angular area is important in the case of nigh t riding, where a range in the 
immediate proximity of headlights has to be observe d. The following dimensions are an information for the 
possible realization: 
 
L  High-pressure xenon lamp (for example XBO 75 W)  
 
H1 Spherical concave mirror: focal length 150 mm; dia meter 40 mm 
 
H2 Spherical concave mirror: focal length 300 mm; diam eter 40 mm 
 
H3 Spherical concave mirror: focal length 300 mm; diam eter 70 mm 
 
 
A   Achromatic lens: focal length 200 mm; diameter 30 mm                            DKS 77: 2012 
 
 
© KEBS 2012 — All rights reserved         
     25 
  
U1, U2   Flat mirrors 
 
BR  Annular diaphragm: diameter of outer circle 21.00 m m; diameter of inner circle 15.75 mm 
 
BL  Circular diaphragm: diameter of aperture 7.5 mm 
 
M   Silicon detector corrected according to curve V  ( λ) with diffusing screen MS 
 
IB 1   Iris-diaphragm to adjust diameter of field of ob servation, diameter 40 mm 
 
IB 2   Iris-diaphragm to eliminate edge effects from IB 1  
 
LB   Circular diaphragm, diameter of aperture 1 mm 
 
P, P'   Positions of visor. 
 
Spherical mirror H 1 forms an image of light source L at diaphragm L B which is in the focal plane of H 2. The 
concave mirror H 3 forms an image of diaphragm L B in the plane of diaphragms B L and B R. The achromatic 
lens A is positioned immediately behind the diaphra gm so that a reduced image of the test sample in po sition 
P appears on diffusing screen MS. The image of iris -diaphragm IB 1 is simultaneously formed on IB2. 
 
  
B.1.2 Measurement 
 
The visor is positioned in the parallel beam to pos ition P, then diaphragm BL is set in place. The flu x T1L 
falling onto the detector corresponds to the undiff used light transmitted by the sample. Diaphragm BL is then 
replaced by annular diaphragm BR; flux T1R falling onto the detector corresponds to the total diffused  light 
originating from the visor and from the apparatus. The visor is then placed at position P'. Flux T2R f alling 
onto the detector corresponds to the diffused light  coming from the apparatus only. 
 
The visor is then brought out of the light beam (e. g. between P and P'). The flux TOL falling on the d etector 
with the diaphragm BL in place corresponds to the t otal light. 
 
B.1.3 Optical qualities; definitions  
 
B.1.3.1 Luminous transmittance 
 
τ = T 1L /T OL  x 100 
 
B.1.3.2   Light diffusion before abrasion DB: 
 
DB = 597 x (T 1R  - T2R )/T 1L  
 
 
B.1.3.3 Light diffusion after abrasion 
 
DA = 597 x (T 1R  - T2R )/T 1L  
 
 
 
 
 
 
 
 
 
 
 
 DKS 77: 2012 
            
                              © KEBS 2012 — All rig hts reserved 26 B.2 Method (b) 
 
2.1. Equipment (See Figure B.1) 
 
 
 
 
Figure B.1 — Test equipment 
 
 
 
 
Figure B.2 — Annular diaphragm D 2 
 
The beam of a collimator K of semi-divergence γ/2 = 17.4 x 10 -4 rd is limited by a diaphragm D 1 with an 
opening of 12 mm against which the sample holder is  placed.   
 
An achromatic convergent lens L 2 corrected for spherical irregularities links the d iaphragm D 1 with the 
receiver R, the diameter of the lens L 2 being such that it does not restrict the light dif fused by the sample in a 
cone with a top half angle of β/2 = 14°. 
 
An annular diaphragm D2 with extended angles αo/2 = 1° and αmax /2 = 12° is placed in a focal image plane of 
the lens L 2 (see Figure B.2). 
 
The non-transparent central part of the diaphragm i s necessary to eliminate the light arriving directl y from the 
light source. It must be possible to move the centr al part of the diaphragm away from the light beam i n such 
a manner that it returns exactly to its original po sition. 
 
The distance between the lens L 2 and the diaphragm D 1, and the focal length F 21
 of the lens L 2 are to be 
chosen so that the image of D 1 completely covers the receiver R.  
 
For an initial incident flux of 1,000 units, the ab solute precision of each reading shall be better th an 1 unit. 
                                                      
1 For L 2 a focal diameter of about 80 mm is recommended .                            DKS 77: 2012 
 
 
© KEBS 2012 — All rights reserved         
     27 
  
B.2.2 Measurements 
 
The following reading shall be taken: 
 
 
 
B.2.3  Optical quantities definitions 
 
B.2.3.1 The luminous transmittance is given by: 
 
(T 2/T 1) x 100 
 
B.2.3.2 The light diffusion before abrasion is give n by: 
 
DB = (T 31  - T30 ) x 100/T 2 
 
B.2.3.3 The light diffusion after abrasion is given  by: 
 
DA = (T 4/T 2) x 100 
 
 
Note: Markings DA and DB correspond to paragraph B. 1.3 of this annex. 
  
 
 
B.3 Method (c) 
 
B.3.1 Equipment 
 
The test arrangement is shown in Figure B.3. 
 
NOTE 1 The measurement principle is identical to th e method (a), but the diameter of the measuring is smaller (approximately 2.5 mm) 
and the test arrangement is simplified. 
 
The beam of the laser (L) is expanded using the two  lenses L1 and L2 and is directed towards the measu ring 
point of the ocular (P). Ocular (P) is positioned i n such a way what it can rotate around the axis of the beam. 
 
The deviation of the beam is a function of the pris matic refractive power at the measuring point. 
 DKS 77: 2012 
            
                              © KEBS 2012 — All rig hts reserved 28 The annular or circular diaphragm, whichever is cho sen, is at a distance of (400 ± 2) mm from the cent re of 
the ocular. The lens A then produces the image of t he centre of the ocular on the photoreceptor S. 
 
The part of the test arrangement, comprising the di aphragms, the lens and the receptor is designed to rotate 
about the vertical axis through the centre of the o cular. 
 
The ocular and the detector part of the apparatus h as to pivot in order to compensate for any prismati c 
refractive power of the ocular. 
 
NOTE 2 For oculars without corrective effect, it is  not necessary, in most cases, for the ocular and t he detector part to pivot. 
 
 
B.3.2 Procedure 
 
B3.2.1 Calibration of the apparatus 
 
Set up the apparatus, the essential features of whi ch are shown in Figure B.3, without the ocular in p lace. 
Put the annular diaphragm B R in place. Rotate the detector part of the apparatu s (consisting of a 
photoreceptor S, a lens A and the annular diaphragm  BR) horizontally about P so as to align the light beam 
from the beam expander (consisting of a lens L 1, with a typical focal length of 10 mm, a lens L2 w ith a typical 
focal length of 30 mm and a circular diaphragm B wi th a pinhole of sufficient size so as to provide a uniform 
beam) with the centre of the annular diaphragm B R. Measure the flux Φ1R  falling onto the photoreceptor S, 
corresponding to the total non-diffused light. Repl ace the annular diaphragm B R by the circular diaphragm B L. 
  
Measure the flux Φ1L  falling onto the photoreceptor, corresponding to t he total non-diffused light. 
 
Obtain the reduced luminance factor for the apparat us, I a* for the solid angle ω using the following equation: 
 
 
Where   Φ1R   is the luminous flux without the visor in the par allel beam and with the annular 
diaphragm B R in place 
 
Φ1L is the luminous flux without the visor in the paral lel beam and with circular diaphragm B L in 
place 
 
ω is the solid angle defined by the annular diaphrag m B R 
 
B.3.2.2  Testing of the visor 
 
Place the visor in the parallel beam at position P as shown in figure 3. Repeat B.3.2.1 with the visor  in place 
and with the visor rotated about the axis of the be am to a position such that the prismatic deviation by the 
visor is horizontal. Rotate the detector part of th e apparatus so that the light beam falls on the cen tre of BR. 
Obtain the reduced luminance factor for the apparat us including the visor, I g* , for the solid angle ω using the 
following equation: 
 
 
where Φ2R is the luminous flux with the visor in the paral lel beam and with the annular diaphragm BR in 
place 
 
Φ2L is the luminous flux without the visor in the pa rallel beam and with circular diaphragm BL in place  
 
ω is the solid angle defined by the annular diaphrag m B R 
 
Then calculate the reduced luminance factor I* of t he ocular using the following equation: 
 
 
 
                           DKS 77: 2012 
 
 
© KEBS 2012 — All rights reserved         
     29 
  
 
 
Figure B.3 — Arrangement of apparatus for measureme nt of light diffusion — Method (c) 
 
 
L  = Laser with wavelength of (600 ±70) nm. 
Note: Class 2 laser recommended. 
< 1mW. Diameter of beam between 0.6 and 1 mm 
 
L1  = 10 mm nominal focal length lens 
 
L2  = 30 mm nominal focal length lens  
 
B  = Circular diaphragm - (a hole of 0.1 mm approx produces a uniform light beam) 
 
P  = Visor sample 
 
BR  = Annular diaphragm, the diameter of the external  circle being (28.0 " 0.1) mm and the inner circle 
(21.0 " 0.1) mm. See Note 2 below. 
 
BL  = Circular diaphragm of 10 mm nominal diameter 
 
A  = Lens, 200 mm nominal focal length and 30 mm no minal diameter 
 
S  = Photoreceptor 
 
The distance between the annular/circular diaphragm  and the centre of the ocular shall be (400±2) mm. 
 
NOTE 1 The focal lengths of the lenses are only giv en as a guide. Other focal lengths may be used, for  example, if a wider beam is 
desired or a smaller image of the sample is to be f ormed on the receptor. 
 
NOTE 2 The diameters of the annular diaphragm circl es shall be measured to an uncertainty not exceedin g 0.01 mm in order that the 
solid angle ω may be determined accurately; any deviation from t he nominal diameters shall be taken into account by  calculation. 
 
 
 
 
 
 
 
 
 DKS 77: 2012 
            
                              © KEBS 2012 — All rig hts reserved 30  
Annex C 
(normative) 
Definitions 
 
The luminous transmittance τv is defined as: 
 
 
The relative visual attenuation quotient Q is defin ed as: 
 
 
where: 
 
τv is the luminous transmittance of the visor relati ve to the standard illuminant D65 
 
τsign is the luminous transmittance of the visor rel ative to the spectral power distribution of the tra ffic signal 
light and it is given by the following equation: 
 
 
where: 
 
SA λ ( λ) is the spectral distribution of radiation of CIE standard illuminant A (or 3200 K light source for b lue 
signal light). See: ISO/CIE 10526, "CIE standard co lorimetric illuminants"; 
 
SD65 λ ( λ) is the spectral distribution of radiation of CIE standard illuminant D65. See: ISO/CIE 10526, "CIE 
standard colorimetric illuminants"; 
 
V( λ) is the spectral visibility function for daylight vision. See: ISO/CIE 10527, "CIE standard colorimet ric 
observers"; 
 
τS ( λ) is the spectral transmittance of the traffic sign al lens; 
 
τV ( λ) is the spectral transmittance of the visor. 
 
The spectral value of the product of the spectral d istributions (SA λ ( λ) ⊕ SD65 λ ( λ)) of the illuminant, the 
spectral visibility function V( λ) of the eye and the spectral transmittance τS ( λ) of the traffic signal lenses are 
given in annex D. 
 
 
 
 
 
 
 
 
 
                            DKS 77: 2012 
 
 
© KEBS 2012 — All rights reserved         
     31 
  
Annex D 
(normative) 
Products of the spectral distribution of radiation of the signal lights and 
Standard illuminant D65 as specified in ISO/CIE 105 26 and the spectral 
visibility function of the average human eye for da ylight vision as 
specified in ISO/CIE 10527 
 
Table D.1 
 
 
 
 
 
 DKS 77: 2012 
            
                              © KEBS 2012 — All rig hts reserved 32  
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
                            DKS 77: 2012 
 
 
© KEBS 2012 — All rights reserved         
     33 
  
Annex E  
(normative) 
Test of refractive powers 
 
E.1 Spherical and astigmatic refractive powers  
 
E.1.1 Apparatus 
 
E.1.1.1 Telescope 
 
A telescope with an aperture nominally 20 mm and a magnification between 10 and 30, fitted with an 
adjustable eyepiece incorporating a reticular. 
 
E.1.1.2 Illuminated target 
 
A target, consisting of a black plate incorporating  the cut-out pattern shown in Figure E.1, behind wh ich is 
located a light source of adjustable luminance with  a condenser, if necessary, to focus the magnified image 
of the light source on the telescope objective. 
 
The large annulus of the target has an outer diamet er of 23 ± 0.1 mm with an annular aperture of 0.6 ±  0.1 
mm. The small annulus has a inner diameter of 11.0 ±0.1 mm with annular aperture of 0.6 ± 0.1 mm. The 
central aperture has a diameter of 0.6 ± 0.1 mm. 
 
The bars are nominally 20 mm long and 2 mm wide wit h a nominal 2 mm separation. 
 
 
Figure E.1 — Telescopic target 
 
 
E.1.1.3 Filter 
 
A filter with its maximum transmittance in the gree n part of the spectrum may be used to reduce chroma tic 
aberrations.  
 
E.1.1.4 Calibration lenses 
 
Lenses with positive and negative spherical refract ive powers of 0.06 m -1, 0.12 m -1 and 0.25 m -1 (tolerance ± 
0.01 m -1). 
 
E.1.2 Arrangement and calibration of apparatus 
 DKS 77: 2012 
            
                              © KEBS 2012 — All rig hts reserved 34 The telescope and illuminated target are placed on the same optical axis 4.60±0.02 m apart. 
 
 
The observer focuses the reticule and the target an d aligns the telescope to obtain a clear image of t he 
pattern. This setting is regarded as the zero point  of the focusing scale of the telescope. 
 
The focusing adjustment of the telescope is calibra ted with the calibration lenses (E.1.2.4.) so that a power of 
0.01 m-1 may be measured. Any other calibration met hod may be used. 
 
E.1.3 Procedure 
 
The visor is mounted in front of the telescope as w orn and measurements shall be taken at the sign poi nts as 
specified in 4.5.9.2.6 
 
E.1.3.1 Spherical and astigmatic refractive powers 
 
E.1.3.1.1 Visors without astigmatic refractive powe r 
 
The telescope is adjusted until the image of the ta rget is perfectly resolved. 
 
The spherical power of the visor is then read from the scale of the telescope. 
 
E.1.3.1.2 Visor with astigmatic refractive power 
 
The target, on the visor, is rotated in order to al ign the principal meridians of the visor with the b ars on the 
target. The telescope is focused firstly on one set  of bars (measurement D 1) and then on the perpendicular 
bars (measurement D 2). The spherical power is the mean, (D 1 + D 2)/2, the astigmatic refractive power is the 
absolute difference, | D 1 - D2 |, of the two measurements. 
 
E.2.  Determination of the difference in prismatic refractive power  
 
E.2.1 Apparatus 
 
The arrangement of the reference method is shown in  figure E.2. 
 
E.2.2.1 Procedure 
 
The diaphragm LB 1, illuminated by the light source, is adjusted in s uch a way that it produces an image on 
the plane B when the visor (P) is not in position. The visor is placed in front of the lens L 2 so that the axis of 
the visor is parallel to the optical axis of the te st assembly. 
 
Adjustable tilt visors are positioned with their oc ular regions normal to the optical axis of the equi pment. 
Measure the vertical and horizontal distance betwee n the two displaced images arising from the two ocu lar 
areas of the visor. 
 
These distances in cm are divided by 2 to give the horizontal and vertical prismatic difference in cm/ m. 
 
If the light paths which correspond to the two eye regions cross, the prismatic refractive power is "b ase in" 
and if the light paths do not cross, it is "base ou t". 
                            DKS 77: 2012 
 
 
© KEBS 2012 — All rights reserved         
     35 
 
 
Figure E.2 — Arrangement apparatus for measurement of prismatic difference 
 
 
 
La = light source, for example, small filaments lamp,  laser with wavelength of 600±70 nm, etc. 
 
J  = interface filter, with peak transmittance in t he green part of the spectrum (required only if a f ilament 
lamp is used as the light source). 
 
L1  = achromatic lens focal length between 20 and 50 mm. 
 
LB1  = diaphragm, diameter of aperture 1 mm nominal  
 
P  = visor 
 
LB 2  = diaphragm as shown in detail A 
 
L2  = achromatic lens, 1,000 mm nominal focal length and 75 mm nominal diameter 
 
B  = image plane 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 DKS 77: 2012 
            
                              © KEBS 2012 — All rig hts reserved 36  
Annex F 
(normative) 
Test for mist-retardance 
 
F.1 Apparatus  
 
Apparatus to determine the change in the non-diffus ed transmittance value, as shown in Figure F.1. 
 
The nominal diameter of the parallel beam is 10 mm.  The size of the beam divider, reflector R and lens  L 3 
shall be selected in such a way that diffused light  is captured up to an angle of 0.75°. If a lens L 3 with a 
nominal focal length f3 = 400 mm is used, the nomin al diameter of a diaphragm is 10 mm. The plane of t he 
diaphragm must lie within the focal plane of the le ns L 3. 
 
The following focal lengths f i of the lens L i are nominal examples and will not affect the test results: 
 
f1 = 10 mm and f 2 = 100 mm 
 
The light source shall be a laser with a wavelength  of 600±70 nm.  
 
The volume of air above the water bath is at least 4 litres. The seating ring has a nominal diameter o f 35 mm 
and a nominal height of 24 mm is then measured to t he highest point of the seating ring. A soft rubber  ring, 3 
mm thick and 3 mm wide (nominal dimensions), is ins erted between the sample and the seating ring. 
 
The water bath container also contains a ventilator  to circulate the air. In addition, there must also  be a 
device to stabilise the temperature on the water ba th. 
 
F.2  Samples 
 
At least 3 samples of the same type are to be teste d. Before the test, the samples are conditioned for  one 
hour in distilled water (at least 5 cm 3 water per cm 2 sample surface area) at 23 ±5 °C, then dabbed dry and 
then conditioned in air for at least 12 hours at 23  ± 5 °C and 50 per cent nominal relative humidity. 
 
F.3  Procedure and evaluation 
 
The ambient temperature during the measurement is 2 3 ± 5 °C. 
  
The temperature of the water bath is set at 50 ±0.5  °C. The air above the water bath is circulated usi ng a 
ventilator, so that it becomes saturated with water  vapour. During this time, the measurement opening is to 
be covered. The ventilator is switched off before t he measurement. 
 
 
To measure the change in the value of the transmitt ance  the sample is placed on the seating ring and 
the time determined until the square of  has dropped to less than 80 per cent of the initia l value of the 
sample without fogging (time without fogging). 
 
 
 
Where  
 
Φb is the luminous flux when there is fogging on the  sample 
 
Φu is the luminous flux before fogging 
 
Initial fogging of maximum 0.5 s duration shall not  be taken into consideration in the evaluation. 
 
 
NOTE 1 Since the light beam passes through the samp les twice, this measurement defines,  
. 
                           DKS 77: 2012 
 
 
© KEBS 2012 — All rights reserved         
     37 
 NOTE 2 The period until the start of the fogging ca n usually be determined visually. However, with som e types of coating the 
formulation of the surface water causes diffusion t o increase more slowly so that visual evaluation is  difficult. The detection apparatus 
described in F.1.1 should then be used. 
 
 
 
 
 
Figure F.1 — Test apparatus for mist-retardant viso r