Tribometers (Slip Test Meters) Compared
This page contains information about America’s and the world’s most used tribometers, or slip test meters, which measure the coefficient of friction (tile COF) of flooring. They are sometimes called floor friction testing devices, or DCOF rating devices.
Tribometer: Pendulum slip/skid tester
Approximate price, USD: $5,988.00
Slip resistance test methods: ASTM E303-22 or EN 16165 or AS 4663 and others. Endorsed by Ceramic Tile Institute of America (CTIOA).
Validation for pedestrian traction: Greater London Council Bulletins 43 (1971) and 145 (1985), in continuous use since 1971 and adopted by at least 50 nations.
Advantage: Well-validated against accident histories and long used with little controversy
Drawback: Bulky, heavy, requires 2-minute onsite assembly and skilled operator
Use: Primary standard for floor slip resistance testing in 50 nations, E303-22 floor and road slip resistance testing, and for Sustainable Slip Resistance testing
Tribometer: SlipAlert (now sold as iAlert Slip Meter)
Price, USD: $1,980.00
Slip resistance test method: Proprietary product — no ASTM standard required
Validation for pedestrian traction: Studies by British and Australian government agencies of SlipAlert vs. pendulum
Advantage: Much smaller, lighter, simpler, more rugged and less costly than pendulum
Drawback: Needs long path length. Also, cart may sometimes veer, bounce or spin, requiring repeating of some runs
Use: Surrogate where pendulum is not economical. Rapid monitoring by minimally trained staff. Visual demo.
Approximate price, USD: $8,995.00 plus charges for annual calibrations
Slip resistance test method: ANSI A326.2 DCOF Acutest. Can also do ANSI B101.1 for dry SCOF testing only.
Previous validation for pedestrian traction (using earlier version of instrument and different test method): University of Wuppertal comparison with human traction, 72 test points including 12 surfaces, two contaminants, three shoe-bottom materials, correlation coefficient 0.93.
Advantage: Printed and electronic records. Very simple to operate.
Drawback: Measures DCOF up to 1.00 only. Very expensive. Can give misleading results since the TCNA is behind the latest test method and “safety criteria”.
Use: Periodic monitoring and new flooring slip resistance quality control using dynamic coefficient of friction. For comparing surfaces, not assessing safety. For that, the pendulum is much more reliable.
Tribometer: Horizontal dynamometer pull-meter static
Approximate price, USD: Low cost but not recommended for pedestrian safety testing. Device not offered by SDA, although we do perform tests if requested.
Slip resistance test method: ASTM C 1028-07, now withdrawn
Validation for pedestrian traction: None. Can give highly deceptive results if applied to slip potential of pedestrian; J. Forensic Sci. March 2007, p. 400.
Advantage: Good workout: uses 50-pound weight lifted 112 times per test.
Drawback: As stated unanimously by ASTM Committee 21.06, not suitable for evaluating slip-fall potential. This standard was withdrawn in 2014, and anyone who promoted its use over the years should now be considered unreliable for all time. It always gave very suspect and unreliable answers, and anyone who did the test knew that back when they were promoting it’s use.
Use: Surface quality control checks by tile manufacturers, in plant or in field.
Tribometer: Tortus III
Approximate price, USD: $6,798.00
Source of test: Proprietary product — no ASTM standard required. Endorsed by Ceramic Tile Institute of America (CTIOA).
Validation for pedestrian traction: University of Southern California Medical Center Study (Tortus II) published in J. Forensic Sci. March 2007, p. 400.
Advantage: Makes printed record. Cost effective for multiple points on a property. Can test short, narrow samples if needed
Drawback: May not assess hydroplaning potential for running person.
Use: Periodic monitoring, dry and wet, using hard and soft rubber test feet.
Tribometer: English XL (VIT)
Approximate price, USD: $4,200.00
The ASTM standard F1679-04e1, the official test method using the Variable Incidence Tribometer (VIT, or English XL) was withdrawn by ASTM with no replacement in 2006 due to its inability to provide a reasonable precision statement; see what Wikipedia’s floor slip resistance testing page has to say about this “instrument” with poor precision that seems to be loved by full-time expert witnesses, who get paid to get the answer that will help win a lawsuit, the truth be damned. This instrument is highly popular amongst these professional “experts” because the result of the test can be easily and heavily influenced by the user to get the desired result. This makes it an excellent tool for an unscrupulous expert witness who needs to get the result desired by the attorney who hired him/her to run the test.
Tribometer: Brungraber Mark IIIB (MkIIIB)
Approximate price: $6,200.00
The ASTM standard ASTM F1677-05 was written for this instrument’s predecessor, the Brungraber Mark II. The Mark IIIB appears to be the same instrument, only shinier and with grooves in the rubber. The ASTM gave the people using the Brungraber Mark II ten years to come up with a reasonable precision statement showing that this instrument was a valid scientific device, and after ten years the ASTM gave up on them and withdrew their standard in 2006. (Seems like 2006 was a long time ago, which has given the users of this instrument another 15 years now to show the Mark IIIB has precision and reproducibility in inter-laboratory studies. We’re still waiting.) The Brungraber manufacturer seems to have decided not to try to get a published standard for the Mark IIIB after the name change, and it appears the main purpose of the name change and the main use of this instrument is to fool juries into believing it’s a real scientific device. Don’t be fooled. In fact, it doesn’t have a peer-reviewed, published test standard in any nation on earth.
Here’s a video showing which instruments can be reliable for assessing the slip resistance of a floor:
And here’s a broader discussion of the various floor slip resistance test methods and floor friction standards.
Need some floor friction testing done on your floor? Click below: