Snell Memorial Foundation
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Started in 1957, the Snell Memorial Foundation is a not-for-profit organization that was created to provide a high quality standard of safety for helmets. As the name implies, the Snell Memorial Foundation was named after William "Pete" Snell, a popular sports car racer who died in 1956 of head injuries he received when the racing helmet he wore failed to protect his head. A group of friends, scientists, doctors, and others joined together to create a group that would promote research and education as well as test and develop standards to improve the effectiveness of helmets.
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[edit] Testing
The Snell Foundation tests helmets in multiple ways, including impact testing, penetration testing, tests on the retaining system and other types depending on the application. After initial laboratory testing, Snell also purchases and tests samples of helmets that are currently on the market in order to confirm compliance. The helmets are vigorously tested in Snell laboratories by Snell technicians. In the event that a certified helmet fails these tests, the manufacturer must take corrective actions to Snell's satisfaction.
[edit] Phases
The testing is done in two phases, the third being optional.
Certification Testing:
- This testing is done before a helmet model may be marketed making any claims of Snell certification. The manufacturer of the helmet submits a number of samples, depending on the helmet type and the standard it is being tested for. These samples are put through the below tests, which are the most exacting tests performed. Any failure on any sample is cause for rejection.
Random Sample Test:
- After passing the initial certification testing, the Snell Foundation acquires additional test samples directly from stocks of helmets that are available to the public. These samples are usually purchased via retail outlets, or directly from a distributor. The number of helmets purchased in this manner relates to the number of other Snell Certified helmets the manufacturer has made. These helmets are then retested. If any of the randomly selected helmets fail any of the tests, three additional helmets are purchased to confirm the test results. If any of these helmets fail, Snell will first demand that the manufacturer discontinue producing the model in question as a Snell certified product. Snell will continue to investigate the matter, and determine a further course of action. This can range from requiring the manufacturer to fix the issue and recertify the helmet, to a complete decertification of the model. In extreme cases, Snell may require that all Snell decals sent to that manufacturer are returned. In order to accomplish this, the manufacturer would have to do a full scale recall of the model in question.
Prototype Testing:
- This test is an unofficial evaluation of a helmet model. Manufacturers may send in one or more sample helmets with a request for specific tests and test configurations. Snell does not consider the results of this test phase when considering a model for certification. This information is available to help manufacturers refine prototypes during product development.
[edit] Tests
In order to qualify for SMF certification, the helmet must pass all or some of the following tests, depending on the application and the requirements of the standard.
Impact Test:
- A series of controlled impacts where the helmet is positioned on a head form and dropped in a guided fall onto variously shaped steel test anvils. Instrumentation in the head form measures the impact in terms of acceleration, or G (gravitational) forces delivered to the head form after absorption by the helmet. If the g forces exceed a certain value, or if the helmet fails to function as designed, the helmet fails.
Positional Stability Test:
- Also known as the Roll-Off test, this test consists of a head form mounted on a stand and pointed with its face downward at an angle of 135 degrees. The helmet is placed on the head form, and adjusted for the best fit. The helmet is also secured with the appropriate straps and buckles as designed by the manufacturer. A wire rope is hooked to the edge of the helmet, and a series of varying rotational loads are placed on the helmet. The helmet passes this test if it does not come off the head form during these trials.
Dynamic Retention Test:
- This test consists of a helmet placed and secured on a head form much like the Roll-Off test. However, in this test, loads are tested against the retaining system, generally consisting of a chin strap, buckling and ancoring hardware of the helmet. The helmet fails this test if the retention system cannot support the mechanical loads or if the maximum instantaneous deflection (stretch) exceeds 30 mm.
Chin Bar Test:
- The chin bar test applies to full face motorcycle helmets, special application racing helmets, and kart racing helmets. The helmet is secured in place facing upwards, and a 5 kg weight is dropped in a guided motion to strike the center of the chin bar. The helmet passes if the strike does not distort the chin bar within a certain distance.
Shell Penetration Test:
- The shell penetration test is applied to motorcycle, special application racing, kart racing, skiing and equestrian helmets. The helmet is mounted to a sturdy base, and a 3 kg striker is dropped in a guided motion to strike the helmet. The striker's end is pointed, and the helmet fails if the shell is penetrated, or the striker manages to contact the head form in any way.
Faceshield Penetration Test:
- This test is commonly performed on full face motorcycle helmets, special application racing helmets, and kart racing helmets that are supplied with a face shield. In this test, the face shield is put into its down position and the helmet is mounted on a rigid base. Using an air rifle loaded with sharp soft lead pellets, the face shield is shot along the centerline in three separate places. The speed of the pellets is approximately 500 km/h. The helmet fails if the shot penetrates, and for racing helmets, if the resulting depression on the inside exceeds 2.5mm.
Flame Resistance Test:
- This test applies to special application racing helmets only. The test consists of using a propane flame with approximately 790 degrees Celsius of heat. The flame is applied to the shell, trim, chin strap, and face shield for a specific number of seconds. Any flame that results from the helmet combusting must extinguish itself within a specified time after the removal of the propane flame. During this test, the interior lining of the helmet must not exceed 70 degrees Celsius.
[edit] Safety
Helmets that pass Snell's testing standards provide the currently highest level of protection available. Snell Standards significantly surpass those set by the U.S. Department of Transportation (DOT), the American National Standards Institute (ANSI), the American Society of Testing Materials (ASTM) and the U.S. Consumer Products Safety Commission's 16 CFR Part 1203.
Because of technical and research developments, and to continue to provide the highest degree of safety to consumers, Snell Standards are updated about every five years. These updates are based on new scientific research and improved, available manufacturing technologies. As such, and in addition to other factors such as typical use wear and tear, Snell recommends that helmets be replaced approximately every five years to ensure good safety.
[edit] Controversy
Published in the June 2005 issue of Motor Cyclist magazine was an in-depth article[1] discussing helmet testing and safety. In the article the Snell Foundation came under some pressure from prominent head injury and helmet design experts, including Dr. Harry Hurt, author of the Hurt Report [2], who described the Snell standards as "a little bit excessive" in reference to the extremely high standard of results the Foundation requires. The Motor Cyclist article found that a softer absorption material would transfer less g-force to the head in the most common motorcycle accidents than the stiffer absorption material found in some Snell-Certified helmets. The Snell Memorial Foundation released a technical critique and rebuttal[3] to the article which is available at their website.
