Slip Resistance Testing Standards in 2021
Updated November 4, 2021
Sotter Engineering Corporation, Mission Viejo, CA USA
Please click on Slip Resistance Testing if you would like a slip test done on your flooring, either in our lab or in the field across the USA and beyond.
|At present, the British pendulum slip/skid tester, the BOT-3000E, and Tortus tribometer are the most useful and reliable floor friction testers to aid in accident prevention. Each has its own appropriate safety standard(s), e.g. 36, 0.42, or 0.50 for a level floor. The information below discusses these slip resistance test instruments and slip test safety standards as well as some others that have been used. Safety Direct America can run slip resistance tests both in the lab or at your site with these instruments (and other test methods upon request), and can also sell you your own floor slip resistance test instruments.|
The basics: to assess slip-related safety we need (1) a published, peer-reviewed slip resistance test method, and (2) a minimum numerical safety criterion for each individual test method, e.g. 36, 0.42, R12, 0.50, 0.60, etc. to apply to the slip test results. Anyone who claims that there is a “generic coefficient of friction value that is considered safe”, such as 0.50, is completely misinformed and seemingly does not have a rudimentary understanding of physics or their stated field of “expertise”. People spreading misinformation such as this are usually full-time American courtroom “experts” who specialize in manipulating the minds and decisions of juries, and they often leave internationally-accepted slip resistance science to others, as their job is to win lawsuits, not to assess real-world slip resistance for architects, building owners, and flooring manufacturers who need to know the truth. If a floor is likely to be lubricated with water, grease, etc. in use it needs to be safe (anti-slip or non-skid) under the expected conditions of use. Dry slip resistance is not an indicator of wet slip resistance — in fact they often vary inversely — so valid wet slip resistance testing of floors is often needed.
Slip Resistance Testing Standards and Safety Criteria
For slip resistance testing wet or dry
The American ASTM E303 slip resistance test standard (as well as many others around the world, such as BS 7976, EN 13036, AS/NZS 4586, CEN/TS 16165, SS 485, etc., etc.) defines the British pendulum tester that is now a national standard for measuring pedestrian floor slip resistance in at least 50 nations on five continents, and it has been endorsed by Ceramic Tile Institute of America since 2001. It is the most widely used and trusted pedestrian slip resistance test device worldwide. It has been in use now for over 50 years, which means its safety criterion is backed by 50 years of research into actual slip and fall accidents around the world. The most common safety standard using the pendulum for a level floor is a minimum Pendulum Test Value (PTV) of 36. The pendulum slip tester is also the basis of the Sustainable Slip Resistance test standard that has been specified by McDonalds Restaurants since 2006, which helps architects and designers see how slip resistance will be effected on a particular tile after a year or two of heavy traffic in use. This helps architects avoid installing a problem, or a tile that will become a problem after some heavy use or improper cleaning methods. Here is a video demo of the pendulum slip resistance tester.
Both hard and soft rubbers are specified for the pendulum, with soft rubber (TRL rubber) being used primarily for barefoot situations such as showers, bathroom floors, and swimming pool decks. The hard rubber is referred to as “Standard Shoe Sole Simulating” rubber, or Four S rubber.
Test results are usually quoted as Pendulum Test Values (or sometimes as BPN, which stands for British Pendulum Number) to avoid the confusion that results when different devices are used to give different values for coefficient of friction. Standards Australia HB 198:2014 gives detailed recommendations of minimum wet Pendulum Test Values (PTV) for many different situations: e.g. external ramps, 54; external walkways and pedestrian crossings, 45; shopping center food courts, 35; and elevator lobbies above external entry level may be 25 or less. There are also barefoot area recommendations based on pendulum tests with the softer rubber slider. The Australian recommendations, published in 1999 and expanded in 2014, are the world’s most detailed and sophisticated standards for pedestrian wet slip resistance. They have now been used by cruise ship companies, major worldwide corporations, and endless other companies outside of Australia. The pendulum is easily the most widely trusted instrument in the world today for assessing real-world slip resistance to aid architects, building owners and flooring manufacturers avoid slip and fall accidents on their properties, and help create more slip resistant flooring products.
ANSI A137.1 and ANSI A326.3 are essentially for use of the BOT-3000E digital tribometer. These test methods can be run wet or dry. This device is not patented. It is presently made in the USA by a single manufacturer. Leather and other test foot materials are also available for this instrument. Both ANSI/NFSI B101.1 and ANSI/NFSI B101.3 have expired, and are therefore no longer considered valid standards. Do not be fooled by online misinformation. The manufacturer of the BOT-3000E used in these tests now enthusiastically discourages the use of both ANSI B101.3 and B101.1. Static coefficient of friction (SCOF) testing (such as in the expired ANSI/NFSI B101.1 and the withdrawn ASTM C1028) in the wet condition has long been known to produce nonsensical and misleading results by the international slip resistance testing community, and any American organization who ever promoted the use of these test methods were, at the time, either purposefully misleading their clients for their own financial gain, or profoundly incompetent in the field of floor slip resistance testing. In most cases, it was clearly the former. Whatever these organizations are selling now as “science” should be considered suspect. They have a long track record of misleading people on the issue of floor slip testing now, and their misinformation has no doubt led to countless deaths and horrific life-changing slip and fall accidents across the USA.
The BOT-3000E does perform a test without human input except for setup and the pressing of an electronic button, which helps eliminate user manipulation. The instrument includes many features that help in validating a test as to time, date of last calibration by the manufacturer, date and time of last verification by the user, date and time and location number of test run, as well as test foot (slider) used, etc. These features can help establish courtroom credibility. See a video demonstration of the BOT-3000E.
Both the BOT-3000E and the Tortus (see below) are capable of making significantly more slip tests per hour than the pendulum, making those instruments valuable for testing and/or comparing multiple areas of a large floor fairly quickly to see if slip resistance varies in different areas of the floor (highly trafficked areas, for example).
The 2012 International Building Code (but don’t be fooled by the word “International” – it’s mainly just used in North America) states that ceramic tile shall conform to the requirements of ANSI A137.1, the current version of which says that testing shall conform to a BOT-3000 dynamic coefficient of friction test. ANSI A137.1 states that tile expected to be walked on wet indoors shall have a minimum DCOF of 0.42. It’s a “pass/fail” test, which is far from ideal, since a commercial kitchen would likely need much more slip resistance than a lobby. It does not provide a minimum DCOF for outdoor areas or ramps. However, the latest version of this test method (ANSI A326.3) also states that this test “can provide a useful comparison of tile surfaces, but it does not predict the likelihood a person will or will not slip on a tile surface.” The official ANSI B101.3 test method, and its safety recommendations, were based on some limited slip and fall research in a laboratory under controlled conditions using numerous human subjects. The modified test outlined in ANSI A137.1/A326.3 apparently is not, and should therefore not be used exclusively to assess the slip risk of any flooring. Wildly misleading much higher-than-reality readings can usually be obtained on polished concrete with the BOT-3000E, for example. The BOT can be a useful tool in certain situations, but not for assessing the actual slip and fall potential of a floor. For that, we recommend the pendulum tester (see above). It’s backed by 50 years of research all over the world.
SlipAlert (left) is a roller-coaster type tribometer that is designed to mimic the readings of the pendulum skid tester. It has been used for field testing, but is of limited utility in laboratory testing because it requires a long path length of flooring. It now has an official British standard for its use in the field – BS 8204-6:2008. Click here to see a SlipAlert Video Demonstration.
The Sigler Pendulum Tester is an older version of the modern British pendulum tester. The Sigler was invented in the mid-20th century by Percy Sigler of the U.S. National Bureau of Standards (now NIST). British workers modified Sigler’s design to produce the modern pendulum skid tester (called the TRRL pendulum tester sometimes in the UK), which is for that reason sometimes known in the USA as the “British Pendulum.” The Sigler pendulum is rarely used now because the modern pendulum exists. The Sigler is no longer commercially available, but a few survive.
The Tortus digital tribometer slip resistance test method is based on a proprietary or patented device, which makes it ineligible to become an ASTM standard. The Tortus has, however, been endorsed as a secondary standard by Ceramic Tile Institute of America (CTIOA) since 2001, with the British pendulum being the primary standard. The advantage of the Tortus, compared to the pendulum, is that it can perform many slip resistance tests in a short period of time, dry and wet, using both hard and soft rubbers. CTIOA has endorsed a minimum dynamic coefficient of friction for level floors of 0.50 using the Tortus slip resistance test method. In 2013, the Tortus III became an official part of the Australian floor slip test standard AS 4586-2013 where it is used as the primary instrument for making dry floor slip resistance readings. Here you can find a Tortus video demonstration.
The former ASTM F1677 applies to the Brungraber Mark II (also known as Portable Inclinable Articulated Strut Tribometer or PIAST) test device (pictured to the left). ASTM withdrew this standard in 2006 approximately one year after it was published, with no replacement. (It is still available from ASTM as a withdrawn or historical standard.) The reasons for withdrawal included poor precision in interlaboratory studies, which made it impossible to present a reasonable precision statement as required by ASTM. In other words, it’s not science. It was very popular with expert witnesses, who can easily get whatever result a lawyer wants them to get by manipulating the instrument during the testing procedure. It has been replaced with another easily-manipulated version of the same instrument, the Mark IIIB.
The former ASTM F 1679 applied to the English XL Variable Incidence Tribometer (VIT), which according to its inventor William English was designed primarily for wet testing (pictured right). ASTM also withdrew this standard in 2006 with no replacement, shortly after it had been published. Again, the reasons included poor precision, which made it impossible to present an acceptable and reasonable precision statement as required by ASTM. In other words, the test method was hurriedly published by the expert witnesses in the ASTM F13 committee to help them win lawsuits in court, but after a year of not being able to provide any kind of reasonable precision statement proving that there was real science behind the test method they had quickly published, the ASTM was forced to withdraw this poor standard, which had been published with bad intent mainly by highly-paid full-time “expert” witnesses.
The English XL’s actuating valve pressurizes the actuating cylinder with gas and drives the test foot onto the surface being tested. The now-withdrawn ASTM slip resistance test procedure required the operator to “fully depress the actuating valve for approximately 1/2 second”. This valve is sensitive to the amount of force or speed used by the operator to depress it (no doubt a part of the precision problem), which raises the possibility that the operator can unwittingly (or wittingly) influence the result according to his or her preconceived notion of whether the floor is slippery or non-slip. If the user presses the button for 3/4 of a second, for instance, the result will likely be much better for the plaintiff. If it is depressed for 1/4 second, the result will be likely better for the defense lawyer. That is why this instrument is hugely popular with full-time professional American slip and fall court “experts.” Getting data from the English XL and Mark IIIB into courtrooms outside of the USA has proven to be very difficult, if not impossible, due to the fact that these instruments do not have a peer-reviewed, published test method in any country on earth, and most countries outside of the USA seem to require “experts” to use real, peer-reviewed science in their testimony.
English XL and Brungraber Mark IIIB users often cite (in a desperate attempt to “prove” that their instrument has some sort of validity, despite not having a published test method) that their instrument passed the ASTM F2508-16e1 standard called the “Standard Practice for Validation, Calibration, and Certification of Walkway Tribometers Using Reference Surfaces”. Although it is necessary for a tribometer to pass this test, it is not sufficient in validating a scientific slip test instrument. This standard was in fact created by American “expert” witnesses for the purpose of making their instruments, which have no published test method, appear “scientific” in their courtroom testimony. This test is often conducted and interpreted by people who have a vested interest in their tribometer having passed the test, and it should not be solely relied upon in deciding whether a slip test device (or tribometer) is trustworthy in predicting human traction. An internationally-accepted, reliable slip test instrument will have been found to correlate well with Variable-Angle ramp tests of human traction, have an official (not withdrawn) test method, and be able to provide a reasonable precision statement as required by all official standard-creating agencies in the world.
At present, there are exactly 195 countries on earth. If not one country has a published slip resistance test method for a particular slip test instrument, it’s most likely because that instrument has not been found to be trustworthy, useful or scientific by the international slip resistance testing community. Many people around the world who test floors for slip resistance are interested in helping eliminate slip and fall accidents, but slip and fall lawsuits in the USA are BIG business, so the American “experts” involved full-time in courtroom testimony have gotten “creative” with the “instruments” they design and use, and somehow they have found ways to use these instruments in American courtrooms, despite the fact glaring lack of a peer-reviewed test standard for these instruments.
ASTM F2508 is based on a study that was conducted at the USC Medical Center, which asked tribometer owners to test four different surfaces and rank them in order of slip resistance. Then pedestrians walked on the same surfaces essentially blindfolded and the number of slips on each were recorded. The findings of this study were published in 2010. The only tribometers that were found to correctly rank the four samples in this study were the British pendulum and the Brungraber Mark II and Mark IIIB. However, the Brungraber devices are not capable of a “reasonable precision statement”, which means every user of this instrument will get a much different answer on the same floor, making it an unreliable and unscientific instrument for measuring pedestrian slip resistance.
Users of the Brungraber Mark IIIB and English XL will cite that their instruments passed ASTM F2508, but the English XL passed it AFTER the initial study (when the correct answers had already been published), and failed it during the study (BEFORE the correct answers were published). The pendulum will always pass ASTM F2508, and here is just one published, peer-reviewed study showing it passes. The fact that ASTM E303 exists also shows that a reasonable precision statement has been presented for the pendulum in the USA.
The Mark IIIB did correctly identify the ranking of the four tiles in the study, but an experienced slip resistance test expert could also reasonably rank these four tiles with their eyes, since the four tiles differ in gloss levels and, therefore, apparent slip resistance. According to ASTM F2508, then, an expert’s eyes, if they can correctly rank the four tiles in the correct order, would now be considered “valid scientific slip resistance test devices.” Anyone who says F2508 “validates their instrument” is not being honest, or does not understand how science works. For example, a thermometer must get approximately the same temperature no matter who is using it to record temperature. ASTM F2508 ignores that fact. A thermometer can’t simply rank ice water, pool water and jacuzzi water in the correct order of temperatures, and then be considered a scientific instrument without telling us what the temperatures of the three waters were. A valid thermometer must be able to give the correct temperature (within a degree or two) for each water. The F2508 cheerleaders and creators claim that their instruments can tell that ice water is colder than jacuzzi water (or, it can rank four tiles in order of slip resistance in one study), and that’s all that matters. The truth be damned for these expert court liars.
ANSI A1264.2 is for Provision of Slip Resistance in the Workplace (2006). This standard is published by ANSI (American National Standards Institute) and references two ASTM standards that now no longer exist, as well as ASTM F609 (see below).
Usefulness of dry slip resistance testing
Dry slip testing can also be useful with or without wet testing. There are several reasons: (1) dry tests followed immediately by wet tests on the same floor can help demonstrate that the slip resistance test method is capable of measuring both high and low values on the subject flooring; (2) a floor may be dry and appear clean, but be slippery due to a thin film of contaminant, for instance grease in or near a restaurant kitchen or parking structure; (3) dry data can help diagnose problems such as furniture polish overspray, inadequate maintenance, airborne cooking fat that settles to the floor overnight, etc.; (4) a rare small spill on a normally dry floor might have occurred too recently for the defendant reasonably to have discovered it and cleaned it up; and (5) many claims of slips and falls are made that involve dry floors. The actual cause of the slip and fall might be footwear, substance abuse, illness, or many other factors unrelated to the floor. Dry testing — particularly before the alleged accident and on a periodic monitoring basis (traction auditing) — can help establish that the floor was safe (or anti-slip) when dry.
For dry slip resistance testing only
ASTM F609 applies to the Horizontal Pull Slipmeter (HPS), which was an early electrically-operated dragsled meter, and does not permit wet slip testing. The HPS is no longer commercially available. The method applies only to the HPS and not to any other device. If this instrument is no longer available, then why does this outdated test method still exist? The ASTM F13 committee that creates these standards in the USA is made up mostly of full-time courtroom “experts”, and people who have an interest in helping American flooring manufacturers “prove” that none of their products are slippery, so American test methods over the years have been poorly written with little regard for science and research and have been almost always eventually withdrawn, left to die slow deaths due to disuse (as in the case of F609), or based on zero research and awaiting someone to recognize that fact and have the test method withdrawn.
ASTM F1678 has to do with the Portable Articulated Strut Tribometer (PAST) which is also known as the Brungraber Mark I. It is a static slip tester (essentially a portable version of the James Machine — see below) and because it suffers from a stiction problem it is not useful for wet testing. ASTM withdrew the standard in 2005. Yes, the methods for the Mark I and Mark II were both withdrawn. Instead of publishing a third test method for the newer Mark IIIB, its users have decided to pretend that ASTM F2508 “validates” their instrument, instead of trying to get yet another test method for the “Brungraber Mark” series of instruments published, and then soon thereafter withdrawn.
ASTM C1028-07 for the Horizontal Pull Dynamometer has now officially been withdrawn as a test method (in 2014) and was intended for quality assurance testing of ceramic tile in and out of the factory. Various American “councils”, “institutes” and other “non-profit organizations” soon discovered that almost all tiles “passed” this test, and adopted it as their preferred floor slip resistance test for many years. These bad actors, acting as experts in floor slip resistance testing, sold test reports to American tile companies saying virtually none of their tiles sold in America were slippery. It was a very lucrative business for these “tile councils” and “safety institutes”. Some of these bad actors have since admitted that it was a mistake to use this method, which was based on zero good research and no good science, and was no doubt the cause of thousands upon thousands of avoidable slip and fall accidents in the USA, many leading to death and life-changing injuries.
The C1028 test involved a 50-pound drag sled that is pulled by a hand-held force meter (dynamometer), and the static coefficient of friction (SCOF) was calculated from the horizontal and vertical forces. This method is not capable of assessing valid pedestrian safety under wet conditions. It was once cited by the U.S. Department of Justice Access Board as a potential test method for compliance with the Americans with Disabilities Act (ADA). The Access Board later withdrew this citation, and now provides no suggested test method or safety standard. Please see www.C1028.info for extensive detail and letters of confirmation from the Access Board. Despite the fact that the ADA never truly endorsed this test method, a great deal of confusion has resulted and misinformation abounds amongst flooring and construction professionals about this horrible test method. This dangerous misinformation was and is still spread by the aforementioned bad actors within the American slip resistance testing community. Take this into account when considering if their present advice on test methods is sound.
ASTM D2047 is the basis of the testing of floor “waxes” (floor finishes) for slip resistance under laboratory conditions. It involves the James Machine with a leather friction pad measuring static friction, and specifies that all testing must be performed dry. It is a laboratory machine that tests flooring samples and due to its design is not usable on an actual floor. Leather is not suitable for wet slip testing, as its properties change unpredictably and permanently when it becomes wet. So if you want to know if a floor is slippery when it’s clean and dry, then this is a good test. Otherwise, the test is silly and worthless, but often used by flooring manufacturers since it will “pass” almost every floor created.
UL410 is an Underwriters Laboratories (UL) standard. It provides for rating of various materials and surfaces as “slip resistant.” Materials or coatings may be listed by UL as slip-resistant if they achieve an index of 0.50 or higher on a James Machine with a dry three-inch-square leather pad. Again, the James Machine is measuring dry static COF, which is the measure of how slippery a floor is when someone is standing still on it while it’s clean and dry. This is irrelevant to measuring pedestrian walking floor slip resistance. Because the test method uses a dry leather pad, it gives lower COF results than if a Neolite or rubber pad were used. Therefore the 0.50 safety criterion is not applicable to friction tests of any kind in which a non-leather pad is used. Unfortunately it has often been applied in this way, indicating that the floor complies with a safety standard when in fact it does not. UL410 is testing a floor that is clean and dry. There has likely never been a legitimate slip on a clean and dry floor in the history of the planet. It must be dusty or wet or greasy or have some sort of contaminant issue in order to be the cause of a slip. So why use this test? To help sell slippery flooring and mislead consumers, of course.
The Technical Products Model 80 is a static slip tester as well and therefore is not suitable for wet testing to assess anti-slip pedestrian safety. SCOF testing in wet conditions is now well-known as an unreliable way of assessing safety.
The American Slip Meter ASM 725 and 825A are also static friction testers, and therefore not suitable for wet testing to assess pedestrian safety. Slip testers such as these can, however, be somewhat useful in determining whether floor maintenance practices are affecting slip resistance over time by using it as a regular monitoring device on dry floors. Note that despite the similarity of the abbreviations, “ASM” is not related to ASTM, and the ASM 725/825A test method is not an ASTM standard.
The Bottom Line for the Property Owner
Those who suffer from slip-and-fall accidents are the accident victims, as well as their family members, and the property owners/managers who are often involuntarily the cause of the accident and must pay damages — either directly or through increased insurance premiums and additional policies written. Many other parties benefit financially from these accidents or sale of the slippery flooring that often causes the life-changing or life-ending falls: flooring vendors, hospitals, physicians, physical therapists, lawyers, expert witnesses, “safety institutes” and “tile councils”, and (through increased premiums) property insurers. Having a valid method of assessing floor safety would therefore seem to be of most immediate value to property owners/managers and architects.
The United States OSHA has long recommended a minimum coefficient of friction (COF) of 0.50 for workplace safety without specifying how the COF is to be determined. This unfortunately is counterproductive and misinformed. Different slip resistance test methods give different results, particularly under wet conditions. Thus the same floor could have coefficients of friction of 0.4, 0.5, 0.6, or 0.7 (or anywhere in between) depending entirely on what test method was used. The OSHA recommendation is therefore meaningless, but has caused confusion for many years.
The slip resistance test devices that are valid for the appropriate purposes today are
- Pendulum Tester for reliable dynamic COF testing wet and dry with hard and/or soft rubber sliders, outdoor area testing, barefoot area testing, Sustainable Slip Resistance Testing, and application of long-established detailed situation-specific standards (swimming pool deck, outdoor ramp, etc.)
- BOT-3000E for cost-effective, rapid and automatically documented dry and wet indoor testing. The results should not, however, be used on their own for assessing actual slip risk. For that, you need pendulum testing.
- Tortus for testing where pedestrians are not likely to be running, and where numerous wet and dry tests are needed with hard and/or soft rubber sliders.
No one of these slip resistance testers is capable of doing all the tasks that might be needed. However, the three slip test devices listed above allow the user ample capability for prevention and analysis of slip and fall accidents in almost any situation.
We here at Safety Direct America can slip test your flooring in our lab or on site, or sell you your own slip resistance tester. Feel free to contact us with any questions. Our knowledge and experience in the field of floor slip resistance testing is unmatched in the Americas.