Flooring Friction Testing (The Good, Bad, and Ugly)
If you specify flooring during design (interior designer/architect/engineer), evaluate flooring post slip/fall (HSE, Risk/Loss, Expert Witness), or use walkway auditing to evaluate the performance of your janitorial staff or BSC do you know what standards exist to test rubber flooring?
In this example, ToMkt's flooring material specification sheet for "Runway", TuffTREAD", and "Atmosphere" provides a good, bad, and ugly example measuring what they call "the coefficient of friction".
First, the "Good". They provide a section in their spec sheet for "coefficient of friction". Manufacturers should always provide guidance to specifiers and end-users as to the "slipperiness" of the flooring material. Without that information how can anyone possibly select the appropriate material for use and understand the risk of slips/falls the flooring material delivers to the built environment.
Second, the "Bad". They use ASTM D2047 "Standard Test Method for Static Coefficient of Friction of Polish-Coated Surfaces as Measure by the James Machine". This is a lab-only test used by manufacturers of floor finishes and NOT to be used as a wet test. DRY ONLY. The D2047 also very clearly says the "0.5 static coefficient of friction (SCOF) compliance criterion of this test method is only appropriate for polish-coated surfaces tested in accordance with this machine and test method". The sensor material used to slide across the surface during the D2047 test is "federal spec leather". The problem with this is that a 0.5 SCOF value measured on a dry, polish-coated surface provides a nonhazardous walkway surface. If there is contamination (e.g. water, oil, grease, food), the pedestrian isn't walking, or the surface is anything other than polish, the 0.5 may not be suitable and should be higher.
ToMkt provides D2047 wet and dry coefficient of friction data for the Atmosphere, Runway, and TuffTREAD materials. They then add that the SCOF, as measured, "exceeds ADA recommended of 0.60 for flat surfaces/0.80 for ramps". There are no ADA recommendations with those values.
If a slip/fall occurs, or facility managers want to understand the COF values resulting from their cleaning processes, they can't use D2047 as it isn't a portable devices. The only published COF-based standards currently available are B101.1 (wet SCOF), B101.3 (wet DCOF), and A326.3 (wet DCOF). Europeans and Australians use pendulum testing which is basically a DCOF value but is provided as "Pendulum Threshold Value". It isn't directly a DCOF value.
Third, the "Ugly". They use ASTM F1677 "Standard Test Method for Using a Portable Inclineable Articulated Strut Slip Tester (PIAST)" and give a value of "Dry > 1.00, Wet 0.98 slip resistance". The first "ugly" thing is that this standard was withdrawn in 2006 (over 12 years ago). The second "ugly" thing is that while the specification section is titled "Coefficient of Friction" any slip meter using F1677 does NOT measure COF but "slip resistance index". If you know what F1677 is you'll realize ToMkt added "slip resistance" after the data but to most readers they will think that they coefficient of friction is 0.98 to 1.00. It's very misleading at a minimum but the fact that the standard was withdrawn over a decade ago it's just "ugly".
Resilient flooring manufacturers have published specifications for materials like vinyl, rubber, linoleum that are used in the manufacturing process by their quality control team. None of the specifications neither define how to test coefficient of friction nor specify a COF that can be used to specify a material for a particular floor area. It's rather amusing that a resilient flooring material, whose only physical interaction with humans is by the interaction of our feet and the flooring surface, doesn't have a defined method of COF measurement and selection guidance for specifiers. There is a big opportunity for improvement.
What can you do?
- Ask your manufacturer's for COF specification information for your flooring material.
- Understand what the COF values mean for slip/fall risk once installed in a particular facility.
- Know what testing methods can be used to evaluate flooring material during selection, post-install, to evaluate ongoing maintenance performance, and if a slip/fall incident occurs
We have a 3-hour Interior Design Continuing Education Council online CEU that explains the concepts of slip resistance, the physics of static and dynamic coefficients of friction, best practice cleaning, flooring types, the zone concept of facilities, how to use walk-off mats, slip meter use, and standards. Invest in yourself:
Flooring: Material Selection and Design Considerations for Health, Safety, and Welfare
Learn to use slip meters. We have a 1-hour online course on how to use the American Slip Meter 825A and several upcoming 1-day courses on how to use the Johnson Forensics GS-1 Slip meter:
Johnson Forensics GS-1 Operator Certificate Course Level 1 & 2, Toronto Sept 27
Johnson Forensics GS-1 Operator Certificate Course Level 1 & 2, Orange, CA Nov 8
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American Slip Meter 825A 1-hour online Operator Certificate Course Level 1
Director of Business Development for Homestead Medical Experts--Expert Witnesses, Nurse Services, Background Checks
5 个月David, thanks for sharing!
Senior Advisor at Growth Management Group, LLC.
6 年a great device. I started with an 825. ASM has been great with their support and their meters are super durable in my experience. looking forward to the dcof unit.
Senior Advisor at Growth Management Group, LLC.
6 年just adding in, the ASM is developing a portable DCOF meter, so on to release. I had them on the phone the other day
Dan, great comments. I spent 9 years at Diversey developing floor care cleaning systems for all types of facilities. Residual surfactant (SLS) is probably a red herring as a key slip cause factor. More significant is bad process (e.g. no agitation or rinsing, letting people walk on a wet floor, damp mopping), contaminants (food/oil/grease), and poor material selection. Devices like the BOT move so far during a test that they need SLS so that the water spreads out evenly. SLS may also result in “smoothing” the COF values of a device that moves improving data quality. Both standards use SBR. Sanding for each standard is defined by the manufacturer. The BOT has a curved sensor, requiring a curved sander, while many slip meters, like the GS-1, have a flat sensor. Note, the A326.3 is not a BOT standard as any equivalent device can be used. Meters pre-microprocessor mostly measured SCOF and only measured a COF value once per test. They were prone to error due to adhesion (mistakenly called “sticktion”). On polished tiles adhesion is an issue. Adhesion can be seen in the first SCOF reading in attached picture. Accurate COF measuring methodology needs repeatable, accurate values and gains nothing from human mimicry.
Let’s leave the world a little better than we found it.
6 年The major differences are the concentration of the SLS solution and the preparation of the 'foot' for the BOT is addressed more thoroughly in A326.3.? I know when we did the round robin testing for A326.3 we tried some different SLS concentrations and had the most consistent results with the lower amount which we felt better approximated a tile where mop water had not been completely rinsed getting re-wetted.? Really you wouldn't walk on a freshly mopped floor before it was rinsed which is what the higher amount of SLS simulates.? ?It's been a while but I think the material on the foot is also different? Also, if you leave a ridge or a flat spot on the foot when you prep the rubber, it can really throw off your results.? From a tile perspective, we used SCOF for years with the pull test and if I can be frank, it just never got there from an R&R standpoint.? If you're telling people you need 0.6 SCOF but the individual tests are coming out between 0.4 and 0.8, there's an issue.? That was pretty typical for tile.? We felt that DCOF did a better job of simulating walking on the floor.? As a bonus, it correlated fairly well to the German ramp which has a good track record in Germany, it's just not doable in the field.?