Draft 2010 STANDARD FOR PROTECTIVE
HEADGEAR
For
Use with Motorcycles and Other Motorized Vehicles
Special Note to Helmet Users
There are four reasons for you to be interested in this Standard:
1.
The use of motorcycles and
other motorized vehicles imposes risks of death or permanent impairment due to
head injury.
2.
The proper use of protective
helmets can minimize the risk of death or permanent impairment.
3.
The protective capacity of a
helmet is difficult to estimate, particularly at the time of purchase or use. Protective capability is currently measured
by destructive testing which is beyond the means most helmet wearers.
4.
Snell certification backed by
ongoing destructive testing of random samples taken from dealers and
distributors identifies those helmet models providing and maintaining the
highest levels of head protection.
Four of the most critical elements affecting a helmet's protective
properties are:
1.
Impact management - how well
the helmet protects against collisions with large objects.
2.
Helmet positional stability -
whether the helmet will be in place, on the head, when it's needed.
3.
Retention system strength -
whether the chin straps are sufficiently strong to hold the helmet throughout a
head impact.
4.
Extent of Protection - the area
of the head protected by the helmet.
This Standard
describes simple tests for all four of these items. However, the tests for the second item,
helmet stability, of necessity presume that the helmet is well matched to the
wearer's head and that it has been carefully adjusted to obtain the best fit
possible. Unless you take similar care
in the selection and fitting of your own helmet, you may not obtain the level
of protection that current headgear can provide.
The Foundation
recommends the simple, straightforward procedure recommended to consumers by
most helmet manufacturers:
Position the helmet
on your head so that it sits low on your forehead; if you can't see the edge of
the brim at the extreme upper range of your vision, the helmet is probably out
of place. Adjust the retention system so
that when in use, it will hold the helmet firmly in place. This positioning and adjusting should be
repeated to obtain the very best result possible. The procedure initially may be time
consuming. Take the time.
Try to remove the
helmet without undoing the retention system closures. If the helmet comes off or shifts over your
eyes, readjust and try again. If no
adjustment seems to work, this helmet is not for you; try another.
This procedure is
also the basis of the test for helmet stability described in this
Standard. This test performs the same
steps but uses standard head forms.
However, you must still perform this procedure for yourself when buying
a helmet and every time you wear a helmet.
Only in this way will you be able to make all the proper adjustments to
get the best fit possible. Furthermore,
your test on your own head will be an improvement on ours; you will determine
whether the helmet is appropriate for you personally.
There are several
other important aspects of helmets to consider.
Full face helmets provide a measure of protection from facial
injuries. The external shell of these
helmets includes a rigid "chin" guard that passes from left to right
over the lower part of the face. The
Foundation has devised special tests for the chin bars of full face helmets.
Some helmets come
with a separate structure which bolts to the helmet and which is intended to
cover the lower part of the face. These
removable chin bars are often intended to deflect small stones and debris
encountered in some motorcycle sports and may not be effective facial
protection in falls and accidents. The
Foundation does not test removable chin bars and considers any headgear
equipped with them to be an open face helmet.
Helmets may also be
equipped with a chin or full face guard that pivots or flips up for the rider’s
convenience. These structures are
considered as integral parts of the helmet and helmets equipped with them are
considered full face helmets and are required to meet all of the test criteria
for full face helmets. These flip up
face guards must always be used in their locked position, or in accordance with
the instructions from the manufacturer. Misuse
of these fixtures may diminish the overall protective capabilities of the
helmet.
If a full face helmet
is equipped with a face shield, it may also provide a measure of eye
protection. The Foundation tests the
face shields of full face helmets for particle penetration resistance. Face shields provided with open face helmets
generally do not provide the same levels of eye protection and, for that reason
are not considered.
The shells of both
open and full face helmets should also provide a measure of protection from
penetration. The Foundation tests the
shells of both full and open face helmets for penetration resistance.
Effective headgear
must be removable. Paramedics and other
emergency personnel must be able to quickly remove headgear from accident
victims in order to check for vital signs and to perform emergency procedures. The Foundation has devised tests and criteria
for helmet removability.
The Foundation tests
helmets for visual field. The helmet
must provide a minimum range of vision appropriate to its use as measured on
standard head forms. Most Snell certified
helmets will meet the requirements stated in this Standard and are considered
appropriate for street use. However, the
Foundation may also certify headgear with much more restricted visual fields
for use only in carefully controlled competitive environments. Such headgear will include warning labels
identifying them as appropriate only for certain activities.
Be absolutely certain
that your helmet is appropriate for your intended uses. Furthermore, since the range of vision you
obtain may vary considerably from our measurement, be absolutely certain that
the helmet and face shield permit you adequate vision.
There are several
important factors which the Foundation does not consider directly but which
bear on the effectiveness of protective helmets. Be certain your helmet is wearable, that is,
that it's comfortable and adequately ventilated when worn for prolonged
periods. Few people will wear an
uncomfortable helmet. A helmet that is
not worn won't protect anyone. Also,
while you’re trying the helmet on, take a good look in a mirror and ask some
friends what they think. Most people
will quit an ugly helmet much quicker than one that is merely uncomfortable.
Check for
conspicuity. Bright colors and
reflective patches will make you more visible to others and therefore less
likely to be involved in a collision.
All your riding gear and especially your helmet should be unmistakable,
even to the most inattentive driver.
FOREWORD
In a motorcycle
accident, the rider may suffer injury or death.
Helmets on the market today offer varying degrees of protection, but the
consumer has little basis for judging the relative effectiveness of a given
model. This Standard presents rational
methods for identifying those helmet models which definitely meet specified
standards for impact (crash) protection and retention system strength and,
afterwards, identifying those which
definitely have ceased to meet those standards.
The Snell Foundation
urges that protective helmets be required for all individuals participating in
supervised racing events and encourages the general public to wear helmets
which meet appropriate performance standards[1].
This 2010 Standard
establishes performance characteristics suitable for motorcycling and for use
with other open motorized vehicles in which the driver and passengers may not
be enclosed such as boats, motorized carts, all-terrain vehicles and
snowmobiles. This Standard does not
establish construction and material specifications. The Foundation does not recommend specific
materials or designs. Manufacturers
voluntarily submit helmets to be tested to this Standard and if the submitted
helmets pass, a certification is issued.
The Foundation will
make available the identity of those products which have been Snell certified
but will not attempt to rank those products according to performance nor to any
other criteria. Neither does the
Foundation distinguish between the needs of participants in competitive events
and those of the general public.
All of the
requirements described herein, including both initial certification and random
sample testing, are an integral part of this Standard. No helmet can satisfy the Standard unless it
is subject to both certification and random sample testing by the Foundation.
Snell certification
for protective headgear requires a specific contractual agreement between the
primary headgear manufacturer and the Foundation. Certification procedures may be obtained upon
application to the Foundation.
SNELL MEMORIAL
FOUNDATION is a registered certification mark and M2010 is a certification mark
of the Snell Memorial Foundation.
INTRODUCTION
This Standard
addresses the problem of protecting the head from direct impact with surfaces
or objects that might be encountered in a motorcycling accident. The Standard prescribes direct measures of
several factors bearing on a helmet's ability to protect the head as well as
its general serviceability as motorcyclist headgear. Thus, this Standard is directed towards the
kinds of performance bearing on head protection that may not readily be
discernable by even knowledgeable consumers at the time of purchase.
Some of these
performance requirements have been expressed in terms of limitations on the
various components and features of the single general helmet configuration
currently available. These expressions
have been used only for the sake of clarity and should not be misinterpreted as
requiring specific configurations or materials.
As newer helmet technologies appear, these limitations will be re-examined
and, perhaps, restated.
A motorcycle helmet
consists generally of a rigid head covering and a retention system composed of
flexible straps and hardware. The rigid
covering consists of a stiff outer shell and a crushable liner. The stiff outer shell protects by its
capacity to spread a concentrated load at its outer surface over a larger area
of the liner and the wearer's head. The
crushable liner protects the head from direct impact by its capacity to manage
impact energy.
The retention system
holds the headgear in position throughout normal usage and especially during
falls and accidents. This Standard
applies two different tests to the retention system. The first of these tests for stability by
fitting the headgear to a standard head form and then attempting to displace it
by applying tangential shock loadings.
The second tests retention system strength by applying a shock load to
the system components through a simulated chin.
The quality of the
fit and the care taken with the adjustments are absolutely critical elements in
these tests. The manufacturer must
provide suitable guidance so that the wearer will be able to select and adjust
headgear to obtain the necessary quality of fit and positional stability.
The capacity for
impact protection is determined by direct measurement of the shock delivered
through the helmet to a head form when the helmeted head form is dropped in a
specified manner onto any of three unyielding anvils.
Most motorcycle
helmets are intended to accommodate a range of head sizes and shapes. Various thicknesses of resilient padding are
sometimes placed within otherwise identical helmets during production or during
fitting to configure the helmet to several different ranges of head size. This resilient padding does not significantly
affect the way the helmet absorbs and attenuates impact and is not directly
addressed in this Standard.
The helmet must also
resist penetration by sharp edged and pointed projections and projectiles. This capacity is tested by placing the helmet
on a head form and dropping a metal cone of specified mass and geometry onto
the shell. The tip of this cone must not
penetrate to the head form.
Similarly, the
helmets must resist chemical attack by bodily fluids as well as solvents and chemicals
associated with motorsports. This
capacity may be tested by applying a solvent mix before further conditioning
and testing.
Full face helmets
provide a measure of facial protection in addition to the impact protection
generally sought. The principle feature
of a full face helmet is a chin bar that extends forward to cover the jaw area
converting the facial opening into a visual port. Frequently, a face shield is also provided so
that the wearer's face is completely covered.
In order to be considered
a full face helmet, the chin bar must be an integral part of the helmet
structure. This interpretation
specifically includes configurations in which the chin bar pivots about a hinge
up and away from the face but excludes simple “bolt-on” chin coverings. The Standard then tests the rigidity of the
chin bar by dropping a weight onto it at a specified velocity so as to attempt
to force the chin bar toward the interior of the helmet. The chin bar must not deflect more than a
specified amount.
If a face shield is
provided with a full face helmet, then this face shield must resist penetration
by small particles. A sharp lead pellet
of a specified weight is directed into the face shield at a specified velocity. The pellet must not penetrate into the helmet
interior.
This Standard also
includes a test intended to determine whether the headgear may be removed from
an unconscious accident victim quickly, easily and reliably in spite of any
damage the headgear might reasonably be expected to sustain. Traditional helmet architectures have
satisfied this requirement so readily that many Standards including previous
Snell Foundation Standards have not mentioned it. Even so, it is unthinkable that a headgear
might protect its wearer in an accident only to thwart attempts at rescue
afterward.
Inadequate
ventilation may render a helmet unwearable in hot climates, especially if the
helmet is full faced. But this Standard
makes no direct demands on either the quantity or quality of air flow to the
wearer.
Other general
features of motorcycle helmets may include eyeshades and accommodations for
goggles, and visibility enhancements such as bright colors and reflective
surfaces. These features all deal with
matters of safety and comfort that are not directly addressed in this Standard
but which merit the consideration of wearers as well as manufacturers.
Although helmet use has been shown to reduce
the risk of head injuries significantly, there are limits to a helmet's
protective capability. No helmet can protect
the wearer against all foreseeable accidents.
Therefore injury may occur in accidents which exceed the protective
capability of any helmet including even those helmets meeting the requirements
of this Standard.
A helmet's protective
capability may be exhausted protecting the wearer in an accident. Helmets are constructed so that the energy of
a blow is managed by the helmet, causing its partial destruction. The damage may not be readily apparent and
the Foundation strongly recommends that a helmet involved in an accident be
returned to the manufacturer for complete inspection. If it is not possible to do so, the helmet
should always be destroyed and replaced.
Finally, the
protective capability may diminish over time.
Some helmets are made of materials which deteriorate with age and
therefore have a limited life span. At
the present time, the Foundation recommends that motorcycle helmets be replaced
after five (5) years, or less if the manufacturer so recommends.
CONSTRUCTION
A. General
The
assembled helmet shall have smooth external and internal surfaces. Any feature projecting more than 7 mm beyond
the outer surface must readily break away; all other projections on the outer
surface shall be smoothly faired and offer minimal frictional resistance to
tangential impact forces. Rivets and
similar projections into the helmet interior must offer no laceration or
puncture hazard. Restraint clips may be
used at the rear or on the side of the helmet.
The helmet shall provide as nearly uniform impact protection over the
entire protected area as is possible.
If the absence of any detachable component of the helmet
does not prevent its being worn, then this absence must not compromise either
the retention system or the impact protection.
If any part of the helmet detaches during testing, it must offer no
laceration or puncture hazard nor reduce the coverage of the head.
If the manufacturer provides add-ons such as visors, face
shields and neck curtains with the helmet, these add-ons must not lessen the
protective capability of the basic helmet nor reduce the visual field below
standard requirements nor create a direct hazard for the wearer.
B. Shell
If
rivets are used, the heads shall not have sharp edges and shall not project
more than 2 mm from the outer surface of the helmet.
C. Materials
Ideally, materials
used in the manufacture of the helmet should be of durable quality and not be
harmed by exposure to sun, rain, dust, vibration, sweat or products applied to
the skin or hair. Similarly, the materials
should not degrade due to temperature extremes likely to be encountered in
routine storage or transportation.
Materials which are known to cause skin irritation or are
conducive to disease shall not be used for the parts which contact the skin. Materials that support the growth of fungi or
algae shall not be used. Fabric lining
or padding materials, if used, may be detachable for the purpose of washing so
long as their absence does not degrade the protective capabilities of the
helmet.
D. Finish
All
edges of the helmet shall be smoothed and rounded with no metallic parts or
other rigid projections on the inside of the shell that might injure the
wearer's head in the event of impact.
E. Retention System
The retention system
shall be designed so as to discourage misuse.
That is, of all the ways in which the retention system might be used,
the design use shall be the simplest and quickest to implement. Helmets shall not be fitted with
"non-essential" features which, if misused, can degrade the
performance. Quick release buckles, if
used, shall not be able to be released inadvertently.
Fabric chinstraps, if
used, shall not be secured to the shell by a bolt, pin or rivet passing through
the fabric itself. Although other
alternatives may be proposed, the preferred method of attachment is that the
strap be looped through and sewn about a metal hanger which can then be secured
to the shell by bolt, rivet or other appropriate means.
F.
Peripheral Vision
The helmet shall
provide peripheral visual clearance as measured using a reference head form
appropriate to the size of the helmet.
This peripheral vision includes a horizontal clearance of at least 210º, an upward clearance of at least 7º and a downward clearance of at
least 30º. However, this downward
clearance makes specific allowance for breath deflectors. These clearances are described in terms of
planes fixed in the reference head forms.
Some competitive
applications may require helmets with more restricted visual fields. When justified, special addenda to this
Standard will define reduced visual fields, the procedures for determining
whether a helmet satisfies the requirement and the additional labeling
requirements warning that the headgear may be appropriate only for certain uses.
G. Sizing
The
requirements of this standard are such that most helmets will perform optimally
only when tested within a range of head circumferences. Outside this range, helmets may still provide
a measure of protection but they may not meet requirements for certification. The manufacturer must specify this entire
range when helmets are submitted for certification. Later, when helmets are distributed for sale,
every helmet shall include a permanent label indicating the range of head
circumferences for which it is intended.
QUALIFICATIONS FOR
CERTIFICATION
For qualification testing, helmets shall be in the same
condition as those offered for sale. No
helmet or component which has been subjected to any tests described in this
Standard shall be offered for sale after testing. A total of five (5) complete helmets must be
submitted by the manufacturer for a certification test program for each
distinct structural configuration of the models offered for sale. Four of these samples will be destroyed in testing,
the fifth shall be retained for comparison and reference.
MODIFICATIONS
Cosmetic
changes to certified headgear are permissible.
Such changes are generally limited to marking or trimming the headgear
with manufacturer approved paint or tape.
Otherwise, modifications to certified headgear effectively create new
configurations which shall not have the confidence and certification of the
Foundation until properly evaluated.
Manufacturers must not place the Foundation's certification label in any
modified headgear without the Foundation’s written authorization.
The Foundation
recommends that helmet owners not modify or contract someone else to modify
their helmets. Any structural
modification may adversely affect a helmet's protective capability. The Foundation’s certification and, quite
likely, all manufacturer warranties apply to the headgear only in its as
manufactured condition.
RANDOM SAMPLE
TESTING
In
addition to the certification testing, the Foundation will routinely obtain and
test samples of previously certified models.
These samples will be selected from among those stocks intended for
retail sale to consumers. In this
manner, the Foundation will attempt to ensure that the helmets made available
to the public continue to meet the performance requirements of this Standard.
In cases where helmets are provided directly to users and
do not pass through a normal sales distribution system, the Foundation will set
up alternative procedures to monitor certified products. Specifically, if helmets are provided
directly to teams or individuals for use in events, the Foundation must have
access to the helmets for spot checking and non-destructive evaluation.
LABELING
AND MARKING
Each
helmet shall have durable, visible and legible labeling identifying the
manufacturer, the month and year of manufacture, the model and the size. Labeling shall be uncoded and either in
English or a language common to the area where the helmets are to be
distributed. The headgear shall also be
labeled to the following effect:
1. No helmet can
protect the wearer against all foreseeable impacts. However, for maximum protection, the helmet
must be of good fit and the retention system must be securely fastened to
retain the helmet. The helmet, when
fitted and fastened, shall not be removed easily.
2. This helmet is so
constructed that the energy of an impact may be absorbed through its partial
destruction, though damage may not be visible.
If it suffers an impact, it must either be returned to the manufacturer
for inspection or be destroyed and replaced.
3. Intended for head
circumferences from XX cm through YY cm.
If any of the helmet
components are sensitive to common solvents, adhesives, paints or cleansers;
the helmet must also bear labels to the following effect:
This helmet can be
seriously damaged by some common substances without visible damage. Apply only the following: (Recommended cleaning agents, paints,
adhesives and the like) as appropriate.
If the helmet model
was certified according to a special addendum to this standard, each helmet
shall also include the warning labels required by that addendum.
Each helmet shall
also include one of the Foundation's serialized certification labels. The Snell certification label shall be placed
either inside or on the outside of the helmet, as appropriate, in such a way
that it cannot be removed intact.
The registered
trademark (certification label) of the Snell Memorial Foundation may be used by
the manufacturer only under license from the Snell Memorial Foundation. The specifics of licensure may be obtained
from the Foundation.
MARKING
AND LABELING OF CRITICAL COMPONENTS
If a helmet component
may reasonably be replaced with an inappropriate substitute that might degrade
wearer safety and performance in any of the tests called out in this standard,
the manufacturer must mark those components so that users may avoid the
purchase and use of inappropriate replacement parts. In particular, face shields on full face
helmets must be marked to identify the manufacturer and the month and year of manufacture.
HEAD FORMS
This standard invokes six standard
head forms for helmet inspection, marking and testing. The geometry of these head forms is according
to the definitions for the ‘A’, ‘C’, ‘E’, ‘J’, ‘M’, and ‘O’ head forms
described in International Standards Organization (ISO) Draft Standard ISO DIS
6220-1983. The impact mass
specifications for the impact test phase are comparable to those in ECE 22-05
for these same head form designations.
ISO DIS 6220-1983 includes
descriptions for half head forms suitable for guided fall impact testing or for
full head forms such as those used in the positional stability tests. Figures 1 and 2 depict the general shapes of
the half head form configuration. The
following table lists useful dimensions from the two references given above.
|
Head Form |
Circumference |
Mass (± 100 g) |
Crown to Basic Plane |
Basic to Reference Plane |
|
A |
50 cm |
3.100 kg ± 100 g |
113.5 mm |
24.0 mm |
|
C |
52 cm |
3.600 kg ± 100 g |
118.0 mm |
25.0 mm |
|
E |
54 cm |
4.100 kg ± 100 g |
122.0 mm |
26.0 mm |
|
J |
57 cm |
4.700 kg ± 100 g |
130.0 mm |
27.5 mm |
|
M |
60 cm |
5.600 kg ± 100 g |
136.0 mm |
29.0 mm |
|
O |
62 mm |
6.100 kg ± 100 g |
140.0 mm |
30.0 mm |
EXTENT OF PROTECTION
The extent of protection corresponds
to that region of the head for which protection is sought.
There are a number of planes fixed in the geometry of
these head forms as shown in Figure 1.
This description of the extent of protection uses the ISO definitions of
the basic plane, the longitudinal plane, the transverse plane and the reference
plane. Other planes have also been
defined strictly for convenience and clarity.
The basic plane corresponds to the
anatomical plane (Frankfort plane) that includes the auditory meatuses and the
inferior orbital rims. The reference
plane is above and parallel to the basic plane. The longitudinal or midsagittal
plane is perpendicular to the basic plane and is the plane of symmetry dividing
the right half of the head form from the left.
The transverse or coronal plane is perpendicular to both the
longitudinal and basic planes. It
corresponds to the anatomical plane that contains the two auditory meatuses and
divides the front from the rear portions of the head.
These planes are all well known entities. Several other planes, however, have proven
useful. The S0 plane is
parallel to the basic plane and lies above it at a distance determined by the
size of the head form. The S3
plane is parallel to the S0 plane and the basic plane and lies
between them. The S4 plane is
also parallel to these planes and lies below the basic plane.
The rear plane divides the rear third of the head from
the front two thirds. It is parallel to
the transverse plane and lies at a given distance behind the point where the
reference plane and longitudinal planes intersect with the front surface of the
head form. The distance from this point,
hereafter called the reference point, is determined by the size of the head
form. The fore plane is also parallel to
the transverse plane. It lies behind the
reference point at a distance determined by the size of the head form.
The extent of protection provided by the helmet must
include the entire region above the S0 plane and forward of the fore
plane, the entire region above the S3 plane and between the fore and
rear planes and the entire region above the S4 plane and behind the
rear plane. Figure 2 and the associated
table lay out these additional defined features and show the extent of
protection and the test line.
|
Figure
2 Extent of
Protection |
|
Head form |
Parameters |
||||
|
Designation |
a |
b |
c |
D |
e |
|
ISO A |
39.0 mm |
128.6 mm |
26.1 mm |
46.8 mm |
52.2 mm |
|
ISO C |
40.6 mm |
133.8 mm |
27.2 mm |
48.4 mm |
54.3 mm |
|
ISO E |
42.2 mm |
139.0 mm |
28.2 mm |
50.0 mm |
56.4 mm |
|
ISO J |
45.2 mm |
148.4 mm |
30.0 mm |
53.0 mm |
60.0 mm |
|
ISO M |
47.4 mm |
155.8 mm |
31.5 mm |
55.2 mm |
63.0 mm |
|
ISO O |
49.2 mm |
161.5 mm |
32.2 mm |
57.2 mm |
64.5 mm |
TESTING
A. Helmet Positioning
Each
helmet model may be subject to meeting test requirements on several different
head forms. The largest appropriate head
form shall be the largest head form whose circumference does not exceed the
upper limit of the intended size range set by the manufacturer. The smallest head form shall be the largest
head form whose circumference does not exceed the lower limit of this intended
size range. If the test technician deems
either of these head forms as too large for the helmet, testing shall be
suspended and a clarification sought.
During
testing, the helmet shall be positioned on each appropriate head form, as
necessary, according to helmet positioning indices provided by the
manufacturer. If the manufacturer fails
to provide positioning information with certification samples, the helmets will
be positioned according to the best judgment of the Foundation's technical
personnel. If the helmets meet
certification requirements, the helmet positioning indices will be those used
in all future testing.
These helmet
positioning indices represent distances on the head form measured from the
basic plane along the intersection with the longitudinal plane to the lower
edge of the helmet.
Helmet
positioning indices will be assigned for all head form sizes appropriate to the
headgear. Each headgear could
conceivably require six helmet positioning indices, one each for the 'A', 'C',
'E', 'J', 'M' and 'O' head forms.
B.
Inspection
Each helmet will be
inspected for the required labels and for compliance with the general
limitations made on structure. The
weight and various measurements will be recorded for comparison with other
samples of the same make and model.
Some helmets may
incorporate innovations and other features not anticipated by this Standard but
which raise concerns about the safety and effectiveness of the headgear. These will be referred to members of the Foundation's
Board of Directors for evaluation. Any
feature deemed to reduce the protective capacity of the headgear, whether
explicitly mentioned in this Standard or not, will be a cause for rejection.
C. Marking
The helmet is placed upon the largest appropriate ISO head
form, positioned according to the apposite helmet positioning index and held in
place with an applied force of 50 newtons (11.25 lbs). The intersections of the shell with the
various defined planes are then traced onto the outer surface of the helmet in
the following manner:
The
level of the S0 plane is marked on that portion of the helmet in
front of the fore plane. The level of
the S3 plane is marked on that portion lying between the fore and
rear planes. The level of the S4
plane is marked on that portion behind the rear plane. Finally, line segments along the fore plane
are marked to join the S0 and S3 planes and, similarly,
line segments along the rear plane are marked to join the S3 and S4
planes.
These lines enclose
the top of the helmet and are the boundary of the required extent of
protection. However, it shall not be a
cause for rejection if parts of this boundary fall below the edge of the
helmet. A test line shall be constructed
within the extent of protection 40 mm from the closest point on the boundary as
shown in figure 2.
If identical helmets
are to be configured with different thicknesses of comfort padding to
accommodate different ranges of head size, the required extent of protection
marked on the test samples shall include the required extent of protection for
each different configuration as marked on the largest head form appropriate for
each. That is: the helmet must meet all the requirements of
this Standard in each of the intended configurations.
D. Peripheral Vision
The
clearance for peripheral vision will be checked by placing the helmet on each
appropriate ISO head form, positioning it according to the apposite helmet
positioning index and holding it in place with a force of 50 newtons. The clearance must include the following
solid angles to the front of the head form:
1. The upward visual
clearance.
2.The lateral visual
clearance.
3.The downward visual
clearance except for the breath deflector allowance.
Helmets certified to
a special addendum to this standard and bearing the warning labels specified in
the addendum will not be subjected to the following procedures and criteria for
evaluating clearances for vision. However, the procedures and criteria
specified in the addendum will be applied instead.
The upward visual
clearance is the solid angle bounded by the reference plane of the head form
and a second plane tilted 7º up from the reference plane. This second plane intersects the reference
plane at two points on the front surface of the head form that are 31 mm to the
right and left of the longitudinal plane as shown in figure 3.
Figure
4 Lateral Visual
Clearance
The lateral visual
clearance, as shown in figure 4, is the solid angle bounded by the reference
plane, the S4 plane and two more planes that are perpendicular to
the reference plane and that contain the reference point on the front of the head
form. One of these two planes forms an
angle of 105º with the longitudinal plane and lies to the left of the head form. The other forms the same angle to the right
of the head form.
The downward visual
clearance is the solid angle bounded by the basic plane of the head form and a
second plane tilted 30º down from the basic plane that intersects it at two
points on the front surface of the head form that are 31 mm to the right and
left of the longitudinal plane as shown in figure 5. However, intrusions into this downward
clearance are permitted so long as the intrusions are within the breath
deflector allowance.
Figure
5 Downward Visual
Clearance
The breath deflector
allowance is shown in figure 6. It
includes the region that is within 31 mm to the right and left of the
longitudinal plane and that lies below the two planes that form 45º angles with
the longitudinal plane and that intersect it at the level of the S4
plane.
E. Performance Testing
The performance
testing subjects helmets to a dynamic test of retention system strength, to a
test for positional stability, to impact management tests, to helmet shell
penetration tests, to a removability test, and to chin bar and face shield
tests if appropriate. These tests are
conducted upon helmet samples kept under laboratory ambient temperature and
humidity or that have been conditioned in one of three environments simulating
some of the conditions in which the helmet might reasonably be expected to be
used.
Figure
6 Breath
Deflector Allowance
Prior to conditioning
and testing, samples may be exposed to solvents common to motorsports which
have been found to attack and degrade some helmet components.
In certification
testing, the first of the four samples is kept at laboratory ambient
temperature and humidity and allowed to come to equilibrium. It is subjected first to the positional
stability test and then to the impact management and other tests. The second, third and fourth samples are
conditioned hot, cold and wet, and subjected to the dynamic test of the
retention system, the impact management test and the other tests.
The selection of
tests, conditioning and special conditioning is left to the discretion of the
Foundation's technical personnel.
However, for certification testing, each of the specified tests shall be
applied to at least one sample.
Furthermore, it is expected that all testing will be conducted so as to
exercise all the likely failure modes of the helmet.
E1. Conditioning for Testing
Test samples may be
kept at laboratory ambient temperature and humidity or may be conditioned cold,
hot or wet according to the specifications given below. At the discretion of the Foundation's
technical personnel and at any point during the testing, a sample previously
kept at ambient may be conditioned cold, hot or wet. However, once a sample has been conditioned
cold, hot or wet, the sample must be maintained in that condition throughout
the rest of the testing.
The special solvent
wipe conditioning described below may be applied to any sample at the
discretion of the Foundation's technical personnel.
a. Special Conditioning. Prior to any impact or
retention system testing helmets may first be conditioned with a solvent mix of
50% toluene and 50% isooctane. A cotton
cloth or suitable substitute shall be soaked in the solvent and used as an
applicator. The solvent will be applied
to the shell first in an area within 5 mm of the chin strap attachments for not
less than five (5) seconds on each side and then applied to the remainder of
the shell for not less than ten (10) seconds.
At least thirty minutes shall elapse before further conditioning and
testing.
b. Cold. The sample shall be conditioned by being
exposed to a temperature of -20 ±2º C for a period of not less than four (4)
hours, or more than twenty-four (24) hours.
c. Heat. The sample shall be conditioned by being
exposed to a temperature of 50 ±2º C for a period of not less than four (4)
hours, or more than twenty-four (24) hours.
d. Wet. The sample shall be conditioned by being
continuously sprayed with water at a temperature of 25 ±5º C for a period of
not less than four (4) hours, or more than twenty-four (24) hours. This spray shall be directed at the helmet's
external surfaces. The helmet shall not
be subjected to total immersion.
All testing of these hot, cold and wet helmets
shall begin within two (2) minutes from the time of removal from the
conditioning apparatus. The samples
shall be returned to the conditioning apparatus between tests.
E2. Positional Stability (Roll-Off)
The
test for positional stability shall only be applied to samples kept at ambient
laboratory temperature and humidity. The
helmet shall not have been subjected to any prior performance testing.
The helmet shall be
tested on the smallest appropriate standard full-face head form. The head form shall be supported on a stand
so that its vertical axis points downward at an angle of 135º to the direction
of gravity. The head form shall be
oriented face down. The helmet shall be
placed on the head form and adjusted to obtain the best configuration of the
retention system. An inelastic strap
shall be hooked to the edge of the helmet at the rear centerline and brought
forward so that its free end hangs downward across the top of the helmet. An inertial hammer shall be suspended from
the free end of the strap. This inertial
hammer shall enable a 4.0 kg ±50 g mass to be dropped through a 0.6 m guided
fall in order to deliver an abrupt shock load to the headgear. The shock load will force the helmet to
rotate forward on the head form. The
helmet may be shifted but must remain on the head form.
The head form shall
be repositioned so that it is facing upward but with the vertical axis still
oriented downward at 135º to gravity.
The helmet shall be positioned and adjusted to obtain the best
configuration of the retention system.
The strap/inertial hammer shall be hooked to the brow edge of the helmet
at the center line so that the strap lies along the centerline and the hammer
is suspended from the top of the helmet.
The shock weight shall be dropped through the 0.6 m guided fall
delivering an abrupt shock load forcing the helmet to rotate rearward. The helmet may be shifted but must remain on
the head form.
The entire portion of
the inertial hammer assembly that participates in the loading of the helmet
shall be such that its mass is no more than 5.0 kg including the 4.0 kg shock
mass.
E3. Dynamic Test of Retention
System
The dynamic test of
the retention system may be applied to any sample either kept at ambient
temperature and humidity or conditioned hot, cold or wet. This test may be performed before, after, or
between any of the other procedures in the test sequence. However, the retention test shall not be
valid if an integral chin bar has been removed from a full face helmet.
The helmet shall be
placed on a head form in such a manner that the chin strap may be fastened
under a device whose upper end approximates the contour of the bony structure
of the jaw. The device will then be
given a mechanical pre-load followed by a dynamic loading. The retention system fails if it cannot
support the mechanical loads or if the maximum deflection during the dynamic
load exceeds 30 mm. The retention system
also fails if it cannot be easily and quickly unfastened after testing.
a. This chinstrap loading device shall consist of a simulated jaw and
accommodations for the pre-load and dynamic load. The jaw portion shall consist of two metal
bars or rollers, each one 12.7 ±0.5 mm in diameter, separated by 76 ±0.5 mm on
center. The mass of this device shall
not exceed 6.0 kg.
b. A pre-load shall be applied for at least 60
seconds. This pre-load plus the mass of
the chinstrap loading device shall total 23 kg±500 g.
c. A 38 kg±500 g mass
shall be dropped in a vertical guided fall a distance of 120 mm so as to load
the retaining system abruptly; the 38 kg mass and pre-load mass shall not be
additive. In order to protect the test
mechanism, the impact of the 38 kg mass may be cushioned with a 00-93 durometer
rubber pad 150 mm in diameter by 62 mm thick, or its equivalent.
E4. Impact Management Tests
The
impact management tests may be performed on samples kept at ambient temperature
and humidity or conditioned hot, cold or wet.
The sample shall not have been subjected to the shell penetration test
beforehand.
These tests involve a
series of controlled impacts in which the helmet is positioned on a test head
form. The helmeted head form is then
dropped in guided falls onto specified test anvils. The impact site and the impact energy must
meet certain requirements in order for the tests to be valid.
If the sample is so
constructed that it interferes with the test equipment preventing impacts at
sites within the test line, then, at the discretion of the Foundation's
technical personnel, parts of the helmet may be cut away to facilitate
testing. Every reasonable effort to
minimize such cutting will be made.
However, there shall be no relaxation of the impact levels or of the
test criteria.
Certain tests shall not be valid
when performed on samples that have been cut for impact testing: the dynamic
strength of retention system test of section E3., the positional stability test
of section E2., the chin bar test of section E5. and the removability test of
section E8.
Special
considerations apply when the helmet is a “flip-up” model, that is: configured
with a chin bar that pivots up and away from the face of the wearer. Whenever possible, the impact tests will be
performed with the chin bar locked in the closed position. In these tests, in addition to all the other
test criteria, the chin bar must not release and “flip-up” inadvertently.
E4.1 Impact
Management Test Equipment
The test equipment
shall consist of at least the following items:
a. The smallest and largest of the head forms
appropriate for the helmet sample. This head
form shall be of rigid, low resonance metal such as magnesium alloy and shall
conform to the 'A', 'C', 'E', 'J', 'M' or 'O' geometries specified in ISO DIS
6220‑1983.
b. A ball‑arm/collar assembly which is
fitted to a socket machined into the base of the head form. The ball/socket configuration shall be such
that the geometrical center of the ball is located on the central vertical axis
of the head form 12.7 mm above the reference plane as described in ISO DIS
6220-1983. The ball-arm/collar assembly
shall also include a uniaxial accelerometer fixed firmly into the ball.
c. A head
form support assembly rigidly attached to the ball-arm. This support assembly shall be such that it
and consequently the head form may be guided in a vertical drop. The mass of this support assembly shall not
exceed 1.2 kg. The total mass of the
head form plus ball-arm/collar assembly plus head form support assembly shall
be within 100 grams of: 3.1 kg for the ISO A head form, 3.6 kg for the ISO C
head form, 4.1 kg for the ISO E head form, 4.7 kg for the ISO J head form, 5.6
kg for the ISO M head form and 6.1 kg for the ISO O head form.
d. A guidance system such that the head form/support
assembly is guided in a vertical drop onto a test anvil. This guidance system may consist of two or
more wires or one or more rails. The head
form/support - guidance system - test anvil alignment shall be such that:
d1. The drop trajectory shall be a
straight line within 3º of vertical and within 5º of the sensitive axis of the
uniaxial accelerometer.
d2. The line parallel to the drop
trajectory and passing through the center of the head form ball-socket shall
pass within 5_mm of the center of the test anvil, within 10 mm of the center of
gravity of the head form/support assembly, and within 5 mm of the sensitive
element of the uniaxial accelerometer.
e. A rigid anvil mount consisting of a solid
mass of at least 500 kg. The upper
surface of the anvil mount shall consist of a steel plate with a minimum
thickness of 12 mm and a minimum surface area of 0.10 m2.
f. Three test anvils : flat, hemispherical and
edge.
f1.
The flat anvil shall have a minimum surface
area of 0.0127 m2, e.g. 127 mm diameter face. When fixed in position on the anvil mount,
the surface shall be perpendicular to the head form trajectory.
f2. The hemispherical anvil shall
have a 48 ±0.5 mm radius.
f3. The edge anvil shall have a
striking face 6.3 mm wide with a depth of at least 35 mm. The radius of the edges on the impact face
shall not exceed 0.5 mm. When in
position, the striking face shall be perpendicular to the head form trajectory.
The anvil shall be sufficiently long
that the ends do not contact the helmet during impact.
g. A uniaxial accelerometer. The acceleration data channel must comply
with SAE recommended practice J 211 requirements for channel class 1000 with
the exception that the frequency response need not include the range from dc to
10 hz which may not be obtainable using certain types of transducers.
h. A velocity measurement device
which will yield the velocity of the head form/support assembly within the last
40 mm of travel before impact. The
velocity measurement must be accurate to within ±1%.
E4.2 Test Definitions
a. The impact site refers to the portion of the
helmet struck during an impact test. It
is defined as the point where a line passing through the center of the head
form ball and the center of the anvil intersects the outer surface of the
helmet at the instant the helmet first touches the anvil.
b. The impact velocity is the velocity of the
head form/support assembly as measured within no more than 4 cm of the first
contact between the helmet and the impact surface.
c. This
standard specifies nominal impact velocities which must be adjusted in order to
allow for deviations between the actual mass of the test head form assembly and
the specified ideal value. The actual
test impact velocity shall be the specified nominal velocity multiplied by the
square root of the value obtained by dividing the ideal head form assembly mass
by the actual mass. For example, if, for
the ‘A’ head form, the mass of the head form plus ball-arm/collar and support
assembly as in paragraph E4.1c masses 3.2 kg instead of the ideal mass of 3.1
kg, the test impact velocities shall be obtained by multiplying the nominal
velocities by a factor of 0.984.
d. There are two levels of test: the first is the standard level used to
identify those helmets which definitely meet this standard. It is applied to samples submitted for
certification testing and to those acquired for the Foundation’s random sample
test (RST) program. The second is the
deviation level which is applied to samples acquired for second round RST
procedures, that is: testing of samples of currently certified models for which
previous samples have obtained failing results in RST testing. Failure to meet test criteria at the
deviation levels indicates that the sample definitely does not meet the
requirements of the standard.
E4.3 Test Impacts
Test
impact sites shall be on or above the test line. Rivets, vents and any other helmet feature
within this region shall be valid test sites.
Each impact site will be subjected to a group of one or two impacts
according to the anvil selected for that site.
The impact site for
the first impact within in a group is the target for the successive impacts in
the same group. However, if an impact
group is sited closer than 120 mm to any previous impact group, that later impact
shall be declared invalid. There is no restriction regarding test
anvil selection. The impact velocities
for each test impact depend on the type of test, on the impact anvil and on the
head form designation. Second impacts do
not apply to helmets in tests against the edge anvil.
The technician may
select either the largest or smallest appropriate head form for any particular
group of impacts. In all cases the
technician may impact any site on the helmet surface on or within the test
lines as drawn for any of the head forms considered appropriate for that
helmet.
The nominal impact
velocities are listed in the following table:
|
Nominal Impact Velocity Table |
|||||||
|
|
Head Form |
||||||
|
ISO A |
ISO C |
ISO E |
ISO J |
ISO M |
ISO O |
||
|
Certification |
1st |
7.75 m/s |
7.75 m/s |
7.75 m/s |
7.75 m/s |
7.75 m/s |
7.75 m/s |
|
2nd |
7.75 m/s |
7.38 m/s |
7.09 m/s |
6.78 m/s |
6.35 m/s |
6.22 m/s |
|
|
Deviation |
1st |
7.48 m/s |
7.48 m/s |
7.48 m/s |
7.48 m/s |
7.48 m/s |
7.48 m/s |
|
2nd |
7.48 m/s |
7.13 m/s |
6.85 m/s |
6.55 m/s |
6.13 m/s |
6.00 m/s |
|
a. Each site
tested against the flat anvil shall be tested according to the values in the
impact velocity table adjusted for the mass of the head form assembly.
b. Each site
tested against the hemispherical anvil shall be tested according to the values
in the impact velocity table adjusted for the mass of the head form assembly.
c. Each site
tested against the edge anvil shall be tested according to the values in the
impact velocity table adjusted for the mass of the head form assembly. No helmet shall be subjected to the second
impact for this anvil.
d. If the impact
velocity for any test impact exceeds the specified mass adjusted velocity by more
than 1.5%, that impact shall be declared invalid.
Please Note: The
impacts described above are based on specific velocities and not prescribed
drop heights. To attain the proper
velocity for an impact, it is likely that the drop height will need to be
adjusted to compensate for frictions inherent in most mechanical helmet testing
systems. Height adjustments for these frictions should not account for more
than 10% of the total drop height. Also,
the 1.5% margin allowed for impact velocity reflects the uncertainties expected
even for well maintained drop equipment.
It is expected that drop heights will always be selected to produce, as
closely as possible, the precise impact velocity as called out in the standards
and adjusted for head form assembly drop mass..
E4.4 Impact Test Interpretation
The
peak acceleration of the head form shall not exceed 290 G’s for any valid
certification impact or 300 G's for any other valid test impact. The helmet’s protective structures shall not
break apart throughout the testing. If
the Foundation's technical personnel conclude that fracture of the helmet
shell, impact liner, retention system or other components could reasonably
imply an undue laceration hazard either from the impact surface or from the
helmet itself, the sample shall be considered to have failed. A flip-up configuration tested with the chin
bar closure locked at the outset of a valid impact and which releases
inadvertently as a result of the impact will also be deemed to have failed.
If, in certification
testing, a sample is found to meet all the test criteria but any two of the
impacts were at less than 98.5% of the specified impact velocity as adjusted
for drop assembly mass, the testing for that sample shall be declared
inconclusive and must be repeated.
Similarly, if there are two instances where an impact falls beyond 10 mm
from the first impacts in its group, the testing for the sample shall be
declared inconclusive and must be repeated.
Finally, if an invalid impact produces a peak acceleration exceeding the
test criterion, the testing for the sample shall be declared inconclusive and
must be repeated.
The impact test
procedures leave considerable latitude to the helmet tester regarding site and
anvil selection. It is expected that the
tester will orchestrate each standard test series in order to investigate
potential weaknesses and to exercise each likely failure mode and will conduct
deviation level testing to exercise the failure modes identified previously.
If at the end of a
certification test series, the Foundation's technical personnel conclude that
the results obtained in valid impacts are not sufficient to determine whether
the helmet model meets the performance requirements of this standard,
additional samples may be conditioned and tested. It is expected that all samples submitted
will meet all the test requirements.
E5. Chin Bar Test
The
chin bar test applies to full face helmets only. At least one helmet in each certification
series shall be tested. The helmet shall
be firmly mounted on a rigid base so that the chin bar faces up and the
reference plane is at 65 ±5º from horizontal.
A mass of 5 ± .2 kg with a flat striking face of 0.01 m5 minimum area shall be dropped in a guided fall so as to strike the
central portion of the chin bar with an impact velocity of 3.5 ±0.2 m/sec. The maximum downward deflection of the chin
bar must not exceed 60 mm nor shall any component fail so as to cause a potential
injury to the wearer.
E6. Shell Penetration Test
The shell penetration
test may be applied to helmets kept at laboratory ambient temperature and
humidity or helmets conditioned hot, cold or wet. At least one helmet sample
shall be tested in shell penetration.
The complete helmet shall be placed on a rigidly mounted head form. The test head form for the penetration test
need not be the standard ISO head form shape used in the impact testing and
helmet marking. It is expected only that
the device used will provide reasonable support for the helmet and conformance
with the interior of the helmet immediately beneath the site of the penetration
test. If the helmet contains a sling or
some other adjustable sizing component, it shall be relaxed to its most
extendable position.
The penetration test
striker shall have a mass of 3 kg ±50 g.
The striker shall fall through a height of 3 m ±15 mm. The point of the striker shall be a cone with
an included angle of 60º ±0.5º and an altitude of 38 ±0.38 mm. The striking tip shall have a hardness of 60
Rockwell (scale C ±3 points) and a radius of .5 ±.01 mm.
The test striker may
be directed at any site on or above the test line but the penetration test site
must be at least 7.5 cm removed from the center of any impact test site or any
other penetration test site. At the test
technician’s discretions, samples may be tested at more than one site on the
shell.
For all penetration tests performed, the test striker
must not penetrate to achieve even momentary contact with the test head form.
E7. Face Shield Penetration
Test
If
a face shield is provided with a full face helmet, this face shield shall be
tested for penetration resistance in the following manner:
The face shield shall
be tested on the appropriate helmet, correctly deployed across the facial
opening and under laboratory ambient conditions. A soft lead pellet weighing 1 ±0.1 g with a
diameter of 5.5 ±0.1 mm and traveling at a velocity of 500 ±20 km per hour
shall strike the face shield normal to the surface. The face shield shall be tested in at least
three different locations: the center
line and 80 ±5 mm to either side of the center line. The pellet must not penetrate to the interior
of the helmet.
E8.
Removability
The helmet
removability test determines whether the helmet can be removed from an
unconscious victim without resorting to any buckles, clasps or other mechanisms
which may be rendered non-functional by impact stresses. The helmet is placed on the largest
appropriate complete ISO head form with all the closures and retention systems
engaged. A technician must remove the
helmet from the head form using simple, common hand tools but without accessing
any of the helmet mechanisms.
The hand tools for
this test are limited to shears, simple edged tools and flat bladed screw
drivers. The operation must not require
more than thirty seconds.
E9. Post-testing Disassembly
and Inspection
If a set of helmets
is submitted for and passes certification testing, at least one of the tested
samples shall be disassembled and inspected.
If the laboratory staff identifies any internal feature that is not
plausible for inclusion in a production helmet, the model shall be
rejected. If an internal projection on
the helmet shell is deemed to present an undue laceration or puncture hazard,
the model shall be rejected. In
evaluating these internal projections, no allowance shall be made for liner
thickness.
At the discretion of
the technician, any helmet may be disassembled in order to check for internal
projections, plausibility or for deviations from the originally certified
configuration.