DOT... Snell...
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My Name is Nobody
Joined: Jul 2005
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From: Las Vegas, NV
DOT... Snell...
There are two organizations setting safety standards for motorcycle helmets in the United States, the Federal Government's Department of Transportation (DOT) and the Snell Memorial Foundation. DOT sets minimum standards that all helmets sold for motorcycling on public streets must meet. The standard is Federal Motor Vehicle Safety Standard 218 (FMVSS 218) and is known commonly as the DOT helmet standard.
The Snell Memorial Foundation is a private not-for-profit organization that sets voluntary standards for motorcycle helmets, bicycle helmets and auto racing helmets, as well as other kinds of protective headgear. Snell standards are the world's toughest. We demand quite a bit more protective capability in helmets than anybody else on the planet.
The table that follows compares the most significant parts of the Snell and DOT Standards, the impact testing. There are other tests in the standards but a helmet's impact performance determines what will happen when a motorcyclist goes headlong into the pavement.
Both Snell and DOT position the helmet on a test headform and then drop that helmeted headform through a two guided falls onto a fixed steel anvil. The test is repeated so that each helmet is impacted on at least four different sites on its surface against either a flat or hemispherical shaped anvil. Snell testing also impacts the helmet against a steel edge anvil that may simulate the edge of a sign stanchion or guardrail. The differences are in impact severity and impact criteria. How big an impact must the helmet withstand and how do the testers determine that the helmet actually withstood the impact.
The severity of an impact can be expressed in terms of how much mechanical energy is generated during the event. The amount of energy is dependent upon the speed or velocity of the head at the moment of impact and it's mass or weight. In helmet testing, the higher the fall or the heavier the headform, the more severe the impact. Since there is always some frictional loss in the test equipment, both Snell and DOT require that the headform velocity be measured just before the helmet impacts the test anvil. Snell measures impact severity in terms of energy, the mass of the headform times the square of the impact velocity divided by two. The table shows the impact energy in joules for anvil type and headform size for each standard. Snell requires that helmets withstand substantially larger impacts than DOT.
Impact criteria tell the testers how to interpret test results. Ancient wisdom has it that it's not the fall that does the damage, it's the sudden stop. Both Snell and DOT measure the suddenness of the stop with an accelerometer, a device used to measure acceleration or in this case deceleration, that is mounted inside the headform. When the helmet smacks into the anvil, the accelerometer measures the headform deceleration throughout the duration of the impact event. This acceleration pulse is generally plotted as G's versus milliseconds where one G is equal to the acceleration due to gravity on the surface of the earth. The testers analyze the acceleration pulse to determine whether the helmet passed or failed the test.
Snell and DOT use different methods to analyze these pulses. Snell limits the peak value to 300 G's. The DOT Standard requires that the peak acceleration not exceed 400 G's but they also put duration limits on the acceleration pulse. The period of time for which the pulse exceeds 200 G's must not be longer than 2 milliseconds. The period of time for which the pulse exceeds 150 G's must not be longer than 4 milliseconds. Snell, among others, questions the validity of these duration criteria. They were taken directly from a ANSI motorcycle helmet standard in 1972. The ANSI standard committee had developed the criteria for testing on an altogether different test device that was already being superseded at the time. After the DOT standard was drafted, the ANSI committee modified their duration criteria for compatibility with current impact test equipment.
DOT never accepted the modification. When the DOT draft was first prepared, DOT expected to make extensive changes in the criteria after its first eighteen months of operation. The 400 G peak and the duration criteria were to have been discarded in favor of the head injury criterion (HIC) as described in another DOT standard, FMVSS 208. However this never came to pass, instead a measure intended to serve only a year and a half has remained in place for over twenty-five years.
There are also administrative differences between Snell and DOT. Snell Certification means that Snell technicians in Snell labs tested samples of the helmet to Snell standards before the helmet was certified. Furthermore, as a condition of certification, Snell regularly buys samples of all Snell certified products and brings them into our lab for follow-up testing.
DOT certification is done on the honor system. The helmet's manufacturer determines whether his helmets satisfy DOT and then claims the qualification for himself. There is not even a reporting requirement. The government does contract for some spot check testing at commercial and private labs but not very much. In recent years much of their effort has been spent against so-called beanie helmets that are obviously substandard and are worn only by helmet law protesters.
Around 1990 a few magazine articles appeared questioning whether Snell certified helmets met the DOT standard. Some went as far as claiming that it was impossible to meet both standards with the same helmet but others were more cautious and said only that meeting both was very difficult.
In fact, Snell certified helmets do meet DOT. If you want to be sure that your helmet meets the DOT standard, get a Snell certified helmet. Manufacturers apply for and earn Snell certification because they care about quality. These are the very manufacturers for whom the honor system works. A Snell sticker is your best assurance that the helmet meets both Snell and DOT. Without our sticker, it's purely a gamble that the helmet meets any standard at all.
The Snell Memorial Foundation is a private not-for-profit organization that sets voluntary standards for motorcycle helmets, bicycle helmets and auto racing helmets, as well as other kinds of protective headgear. Snell standards are the world's toughest. We demand quite a bit more protective capability in helmets than anybody else on the planet.
The table that follows compares the most significant parts of the Snell and DOT Standards, the impact testing. There are other tests in the standards but a helmet's impact performance determines what will happen when a motorcyclist goes headlong into the pavement.
Both Snell and DOT position the helmet on a test headform and then drop that helmeted headform through a two guided falls onto a fixed steel anvil. The test is repeated so that each helmet is impacted on at least four different sites on its surface against either a flat or hemispherical shaped anvil. Snell testing also impacts the helmet against a steel edge anvil that may simulate the edge of a sign stanchion or guardrail. The differences are in impact severity and impact criteria. How big an impact must the helmet withstand and how do the testers determine that the helmet actually withstood the impact.
The severity of an impact can be expressed in terms of how much mechanical energy is generated during the event. The amount of energy is dependent upon the speed or velocity of the head at the moment of impact and it's mass or weight. In helmet testing, the higher the fall or the heavier the headform, the more severe the impact. Since there is always some frictional loss in the test equipment, both Snell and DOT require that the headform velocity be measured just before the helmet impacts the test anvil. Snell measures impact severity in terms of energy, the mass of the headform times the square of the impact velocity divided by two. The table shows the impact energy in joules for anvil type and headform size for each standard. Snell requires that helmets withstand substantially larger impacts than DOT.
Impact criteria tell the testers how to interpret test results. Ancient wisdom has it that it's not the fall that does the damage, it's the sudden stop. Both Snell and DOT measure the suddenness of the stop with an accelerometer, a device used to measure acceleration or in this case deceleration, that is mounted inside the headform. When the helmet smacks into the anvil, the accelerometer measures the headform deceleration throughout the duration of the impact event. This acceleration pulse is generally plotted as G's versus milliseconds where one G is equal to the acceleration due to gravity on the surface of the earth. The testers analyze the acceleration pulse to determine whether the helmet passed or failed the test.
Snell and DOT use different methods to analyze these pulses. Snell limits the peak value to 300 G's. The DOT Standard requires that the peak acceleration not exceed 400 G's but they also put duration limits on the acceleration pulse. The period of time for which the pulse exceeds 200 G's must not be longer than 2 milliseconds. The period of time for which the pulse exceeds 150 G's must not be longer than 4 milliseconds. Snell, among others, questions the validity of these duration criteria. They were taken directly from a ANSI motorcycle helmet standard in 1972. The ANSI standard committee had developed the criteria for testing on an altogether different test device that was already being superseded at the time. After the DOT standard was drafted, the ANSI committee modified their duration criteria for compatibility with current impact test equipment.
DOT never accepted the modification. When the DOT draft was first prepared, DOT expected to make extensive changes in the criteria after its first eighteen months of operation. The 400 G peak and the duration criteria were to have been discarded in favor of the head injury criterion (HIC) as described in another DOT standard, FMVSS 208. However this never came to pass, instead a measure intended to serve only a year and a half has remained in place for over twenty-five years.
There are also administrative differences between Snell and DOT. Snell Certification means that Snell technicians in Snell labs tested samples of the helmet to Snell standards before the helmet was certified. Furthermore, as a condition of certification, Snell regularly buys samples of all Snell certified products and brings them into our lab for follow-up testing.
DOT certification is done on the honor system. The helmet's manufacturer determines whether his helmets satisfy DOT and then claims the qualification for himself. There is not even a reporting requirement. The government does contract for some spot check testing at commercial and private labs but not very much. In recent years much of their effort has been spent against so-called beanie helmets that are obviously substandard and are worn only by helmet law protesters.
Around 1990 a few magazine articles appeared questioning whether Snell certified helmets met the DOT standard. Some went as far as claiming that it was impossible to meet both standards with the same helmet but others were more cautious and said only that meeting both was very difficult.
In fact, Snell certified helmets do meet DOT. If you want to be sure that your helmet meets the DOT standard, get a Snell certified helmet. Manufacturers apply for and earn Snell certification because they care about quality. These are the very manufacturers for whom the honor system works. A Snell sticker is your best assurance that the helmet meets both Snell and DOT. Without our sticker, it's purely a gamble that the helmet meets any standard at all.
Honda-Tech Member
Joined: May 2000
Posts: 9,817
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From: San Gabriel, CA
Here is a description of the differences between Snell, ECE2205, and BSI6658A.
http://helmetharbor.com/snell/comparison.htm
(text follows):
What are the real differences between Snell M2000, ECE 22-05 and the BSI 6658 Type A safety standards?
NOTE: This comparison has been conducted for informational purposes ONLY. Our intent is not to say one standard is better than the other, we leave that to our customers. No one at the Helmet Harbor protests to be experts of each test, but we have done our best to present the facts as published by each organization.
Pre-release Testing (Before the helmets hit the streets for purchase):
SNELL - Before a helmet can be sold with the SNELL sticker, the company must first submitted 5-6 helmets to SNELL for testing. This number can vary depending on the helmet type and Snell Standard. If ALL helmets pass the testing, the manufacture is free to purchase the SNELL sticker for that helmet model only.
BSI 6658 Type A & ECE 22-05 - Before a helmet can be sold with a BSI 6658 Type A, or ECE 22-05 sticker the manufacture must submit a "batch" to be tested. The batch size depends on how many helmets the manufacture is releasing for sale. 5 for the production batch of 500, 13 for a batch of 501-1,200 and 20 helmets for a production batch of 1,201-2000. If the helmets pass ALL the tests, stickers are released for that specific batch and in that specific quantity.
Note: The ECE 22-05 helmets are tested by BSI, and have the BSI Kitemark.
Failed Tests:
SNELL - The manufacture must correct the problem, and a new set of helmets must be submitted.
BSI 6658 Type A & ECE 22-05 - If any helmet fails the test, the entire batch is rejected. New helmets must be submitted for re-testing, following investigation of the problem and remedial action.
Post-release Testing:
SNELL - SNELL uses random testing, and purchases helmets off the dealer showroom floor. If a helmet fails the random test, the manufacture is notified, and further random tests are preformed. If further tests show repetitive failures, discussions are had between SNELL and the manufactures on ways to come back into compliance. If further issues arise, the manufacture could loose their certification status. SNELL states they test "Up to .25%" of all SNELL certified post-release helmets.
BSI 6658 Type A & ECE 22-05 - Annual re-certification, and quarterly factory inspections.
Testing Procedure:
The following link will take you to a page containing the SNELL impact comparison information. We feel this is an accurate comparison, and does a good job of stating the facts. Again, we leave it to our customers to make decisions based on the information.
SNELL Comparison
What racing organizations are each approved for use?
SNELL - FIM, PIM, AMA, Formula-USA, WERA, CCS.
BSI 6658 Type A - FIM, PIM, AMA, Formula-USA, WERA, CCS.
ECE 22-05 "P" - FIM, PIM, AMA, Formula-USA, WERA, CCS.
http://helmetharbor.com/snell/comparison.htm
(text follows):
What are the real differences between Snell M2000, ECE 22-05 and the BSI 6658 Type A safety standards?
NOTE: This comparison has been conducted for informational purposes ONLY. Our intent is not to say one standard is better than the other, we leave that to our customers. No one at the Helmet Harbor protests to be experts of each test, but we have done our best to present the facts as published by each organization.
Pre-release Testing (Before the helmets hit the streets for purchase):
SNELL - Before a helmet can be sold with the SNELL sticker, the company must first submitted 5-6 helmets to SNELL for testing. This number can vary depending on the helmet type and Snell Standard. If ALL helmets pass the testing, the manufacture is free to purchase the SNELL sticker for that helmet model only.
BSI 6658 Type A & ECE 22-05 - Before a helmet can be sold with a BSI 6658 Type A, or ECE 22-05 sticker the manufacture must submit a "batch" to be tested. The batch size depends on how many helmets the manufacture is releasing for sale. 5 for the production batch of 500, 13 for a batch of 501-1,200 and 20 helmets for a production batch of 1,201-2000. If the helmets pass ALL the tests, stickers are released for that specific batch and in that specific quantity.
Note: The ECE 22-05 helmets are tested by BSI, and have the BSI Kitemark.
Failed Tests:
SNELL - The manufacture must correct the problem, and a new set of helmets must be submitted.
BSI 6658 Type A & ECE 22-05 - If any helmet fails the test, the entire batch is rejected. New helmets must be submitted for re-testing, following investigation of the problem and remedial action.
Post-release Testing:
SNELL - SNELL uses random testing, and purchases helmets off the dealer showroom floor. If a helmet fails the random test, the manufacture is notified, and further random tests are preformed. If further tests show repetitive failures, discussions are had between SNELL and the manufactures on ways to come back into compliance. If further issues arise, the manufacture could loose their certification status. SNELL states they test "Up to .25%" of all SNELL certified post-release helmets.
BSI 6658 Type A & ECE 22-05 - Annual re-certification, and quarterly factory inspections.
Testing Procedure:
The following link will take you to a page containing the SNELL impact comparison information. We feel this is an accurate comparison, and does a good job of stating the facts. Again, we leave it to our customers to make decisions based on the information.
SNELL Comparison
What racing organizations are each approved for use?
SNELL - FIM, PIM, AMA, Formula-USA, WERA, CCS.
BSI 6658 Type A - FIM, PIM, AMA, Formula-USA, WERA, CCS.
ECE 22-05 "P" - FIM, PIM, AMA, Formula-USA, WERA, CCS.
Joined: Feb 2003
Posts: 199
Likes: 0
From: Uranus, Milky Way
Re: DOT... Snell... (MSchu)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by MSchu »</TD></TR><TR><TD CLASS="quote">
DOT certification is done on the honor system. The helmet's manufacturer determines whether his helmets satisfy DOT and then claims the qualification for himself. There is not even a reporting requirement. The government does contract for some spot check testing at commercial and private labs but not very much.</TD></TR></TABLE>
Isn't that scary? They don't even have to be tested first to have a DOT sticker on them.
Will Snell ever rate helmets on a scale versus just a pass/fail?
DOT certification is done on the honor system. The helmet's manufacturer determines whether his helmets satisfy DOT and then claims the qualification for himself. There is not even a reporting requirement. The government does contract for some spot check testing at commercial and private labs but not very much.</TD></TR></TABLE>
Isn't that scary? They don't even have to be tested first to have a DOT sticker on them.
Will Snell ever rate helmets on a scale versus just a pass/fail?
Honda-Tech Member
Joined: Jun 2000
Posts: 4,200
Likes: 0
From: One by one, the penguins steal my sanity.
Re: DOT... Snell... (UNCVLZD)
Yet another article (read the whole thing, including the response, and draw your own conclusions)...
http://www.motorcyclistonline.com/gearbox/hatz/
http://www.motorcyclistonline.com/gearbox/hatz/
