Slip Resistance Testing Standards in 2019
The basics: to assess slip-related safety we need (a) a slip resistance test method, and (b) a minimum numerical safety criterion, e.g. 0.42, 0.50, 0.60, etc. to apply to the slip test results. If the 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 is often needed.
Slip Resistance Testing Standards and Safety Criteria
For slip resistance testing wet or dry
ANSI B101.1, B101.3, A137.1, and A326.3 are essentially for use of the BOT-3000E digital tribometer. It is presently made in the USA by a single manufacturer. The BOT-3000E and the corresponding ANSI standards are for wet testing of floors using hard rubber sliders (test feet). ANSI B101.1 measures static friction, which should not be used on its own for assessing anti-slip safety. ANSI B101.3 measures dynamic friction at a lower speed than the British pendulum. The ANSI dynamic method is sometimes used, without water, to assess dry friction. Leather and other test foot materials are also available for this instrument.
The BOT-3000E performs a test without human input except for setup and the pressing of an electronic button. 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, age of and number of runs on that test foot, etc. These features help establish courtroom credibility. See a video demonstration of the BOT-3000E.
The safety standards ANSI specifies for a level floor using the B101.3 dynamic test method is a “high slip resistance” minimum dynamic coefficient of friction (DCOF) of 0.43 and a “low slip resistance” minimum DCOF of 0.30. When DCOF is assessed for a floor or sample, it is probably not necessary to assess SCOF. The Tile Council of North America and the Concrete Polishing Association of America both specify that their members use the BOT-3000E to do a DCOF test. (Static friction is applicable to a pedestrian who is standing still. An anti-slip floor or slip resistant floor will be anti-slip for someone who is in motion moving across the floor. Static coefficient of friction slip testing is therefore irrelevant.) The 2012 International Building Code states that ceramic tile shall conform to the requirements of ANSI A137.1, the current version of which (2015) 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 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, are based on actual 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.
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
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.
The Bottom Line for the Property Owner
Those who suffer from slip-and-fall accidents are the accident victims, 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 them: flooring vendors, hospitals, physicians, physical therapists, lawyers, expert witnesses, 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.
The United States OSHA has long recommended a minimum coefficient of friction (COF) of 0.50 for workplace safety.