There are four reasons for you to be interested in this Standard:
1. The use of 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 measure, particularly at the time of purchase or use.
4. Snell certification backed by ongoing random sample testing 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.
A fifth element applies to helmets used in automobile racing but not necessarily for those used in kart racing:
5. Flame Resistance - whether the helmet will withstand exposure to direct flame.
This flame resistance may well mean survival for well belted drivers and passengers in a crashed vehicle where a few seconds of additional time may enable escape or rescue. Helmets satisfying Snell requirements for all five of these elements may be identified by the Foundation’s orange “SA2005" certification label. Those meeting requirements for the first four elements but not tested for flame resistance may be identified instead by the Foundation’s light blue “K2005" certification label.
This Standard describes simple tests for all five 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 headforms. 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 that bolts to the helmet in order to cover the lower part of the face. These removable chin bars are often intended to deflect small stones and debris encountered in some 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.
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 as measured on standard headforms. However, the range of vision you obtain may vary considerably from our measurement.
It is also important to remember that the visual field requirements are based on the needs of people participating in well regulated and controlled events. For this reason, the requirements are considerably less than those the Foundation requires for street use headgear such as for motorcycle helmets. Be absolutely certain that the helmet and face shield permit you adequate vision for every intended use. Specifically, if your automotive racing helmet is only sufficient for controlled track events, don't use it for street motorcycling.
Finally, 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. Most people will not wear an uncomfortable helmet, at least, not for very long. A helmet that is not worn won't protect anyone.
In a racing accident, drivers and passengers 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 helmets which definitely meet specified standards for impact (crash) protection 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 .
This 2005 Standard establishes performance characteristics particularly suited to the conditions of automotive racing which may include complete harness and restraint systems, elaborate roll bar cages, and reduced visual field requirements. 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 SA2005 is a certification mark of the Snell Memorial Foundation.
This Standard addresses the problem of protecting the head from direct impact with surfaces or objects that might be encountered in a racing 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 automotive racing 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 racing 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 headform 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 headform when the helmeted headform is dropped in a specified manner onto any of three unyielding anvils. A fourth anvil is used to test impact protection for repeated strikes against a roll cage assembly.
Most racing helmets are intended to accommodate a range of head sizes and shapes. Various thicknesses of resilient padding materials 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 projectiles such as parts of exploding engines or other damaged mechanical assemblies. This capacity is tested by placing the helmet on a headform and dropping a metal cone of specified mass and geometry onto the shell. The tip of this cone must not penetrate to the headform.
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.
Since auto racing drivers are frequently unable to escape quickly from accident involved vehicles, their helmets must also provide some measure of protection against fire. Exposed helmet components, whether internal or external must be flame resistant. They must not be combustible and when exposed to high temperatures, must self extinguish when the heat load is removed. Since flame resistance is not considered important for kart racing applications and since the materials and treatments necessary for flame resistance add appreciably to the production costs of the headgear, these requirements are waived for kart racing helmets.
Helmet components are tested separately for flame resistance by exposing them to a direct propane flame of a specified temperature for specified time periods. When the flame is withdrawn, each of these components must self extinguish within a specified time limit. Furthermore, when the helmet shell is tested, the temperature of the padding or lining materials within the helmet that would presumably touch the wearer's head must not exceed 70°C.
The chin strap must also be flame resistant. The chin strap will be tested similarly to other helmet components. It must not melt and must self extinguish within the allowed time.
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 face shield must also withstand a flame resistance test. As with other components, the face shield must be self extinguishing within an allotted time. Furthermore, the face shield must not melt down allowing the flame to reach the interior of the helmet.
Finally, this face shield must have a positive "hold down". Since inadvertent displacement of the face shield during racing could have disastrous consequences, the only way to remove or raise the face shield from its normal operating position must involve the deliberate disengagement of some catch mechanism. Friction mechanisms will not satisfy this requirement.
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.
Ventilation, and forced air ventilation is an important consideration in automotive racing. This Standard does not limit the diameter of ventilation holes in the helmet shell but makes specific mention of the kinds of ports and fittings appropriate for forced air ventilation. However, there are no direct demands on either the quantity or quality of air flow to the wearer.
Other general features of racing helmets may include eyeshades and accommodations for goggles. These features 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 racing helmets be replaced after five (5) years, or less if the manufacturer so recommends.