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Frequently Asked Questions:
- Is the Slip-Test Mark II or Mark IIB still available?
Mark II was superseded by the re-engineered Mark IIB; both use a
10 pound weight for actuation (rather than the spring used in the Mark
IIIB), but the Mark IIIB is better for most tribometry. Because
of this, and due to lack of demand for the Mark IIB, these are no
longer in production.
- The NFSI floormat test method
101-C, referenced in the NFSI floormat "high-traction" certification
process in NFSI B101.6, specifies the use of the Mark II or Mark III
tribometer. What is the relationship between Slip-Test and NFSI
in terms of this NFSI standard?
- Slip-Test has had no relationship with NFSI and does not support the methodology or reliability of their
floormat certification process. The
Mark II and Mark III (and Mark IIB / Mark IIIB) tribometer designs
require a fairly stiff testfoot material, above approximately Shore 35A
durometer. The tribometer will not work correctly
with softer rubber, foam, or textile substrates below Shore 35A
used on floormats. It would be necessary to basically disable the
normal functionality of the Mark II / III / IIB / IIIB when testing
such softer materials - measurements will not be reliable.
is a lot of information on the internet about the Mark II tribometer
and the withdrawn ASTM F1677 standard for it. What is the
relationship between the re-engineered Slip-Test tribometers
the withdrawn F1677?
F1677 Standard Test Method as
written described the original Slip-Test Mark II PIAST tribometer
produced by Robert Brungraber. The Mark III tribometer and the
re-engineered Mark IIIB and Mark IIB tribometers
all operate similarly and can be used per F1677. The
withdrawn by ASTM in 2006 for two reasons:
F1677 test method referred to a "proprietary device", which is not
allowed by ASTM where "alternatives exist".
But experts know that due to the nature of friction testing
its dependence on the operational characteristics of the
tribometer, there are no "alternatives" to the Mark II - not
English XL, not even the Mark III. These devices are not
alternates to each other. They operate differently and will
provide different results on the same surface - this is expectable, and
does not diminish their individual capabilities.
ASTM-required precision and bias statement was never published
in the F1677 test method.
A precision and bias (P&B) statement is derived from
Interlaboratory Study, involving multiple tribometers and operators,
and statistical analysis of the results. It is widely
that the lack of a published P&B statement in F1677 proves a
critical deficiency in the performance of the Mark II.
numerous Interlaboratory Studies had been conducted using the Mark II,
prior to 2006 - some of these studies are discussed in
Technical Report TR-A1264.3-2007, available from
Nevertheless, there is a difference between having a P&B
statement and actually getting it published in a standard -
procedural and political issues can significantly hamper
standards creation. The results of those past Interlaboratory Studies
speak for themselves, regardless of whether an associated P&B
statement was able to be published in ASTM F1677.
re-engineered Slip-Test Mark IIIB tribometers, though operationally identical to
the original Mark III designed by Robert Brungraber, use improved materials
and manufacturing methods, and provide different results
to the originals) on the same walkway surface. Both the Mark IIIB and the (now out of production) Mark IIB have
successfully passed ASTM
F2508 Validation - a distinction that few tribometer
designs have achieved. Further, the Mark IIIB has
a precision and bias statement as part of its achievement of Certification to ASTM F2508
- see the P&B statement in our Certification Report here!
The report also contains the test method Slip-Test recommends
- which significantly differs from ASTM F1677.
- What is the
status of the NBS/NIST-Brungraber Mark I, as used in the ASTM F462 test?
does not manufacture, rent, sell, or service Mark I tribometers, which
were last sold new in 1993.
Slip-Test offers for purchase full-scale scans of 17 original
Mark I manufacturing drawings, circa 1975.
A few of the
technical publications that reference Slip-Test tribometers:
WR et al. Development of an objective determination of a slip
with a portable inclineable articulated strut slip tester (PIAST). Safety Science 48
- McCorry RW et al. The anatomy of a
slip: kinetic and kinematic characteristics of slip and non-slip
matched trials. Applied
Ergonomics 41 (2010), 41–46.
- Powers CM et al. Validation of
walkway tribometers: establishing a reference standard. Journal of Forensic Sciences,
March 2010, Volume 55, Number 2, 366-370.
- Leffler JP. Forensic engineering
use of walkway traction testing. Journal
of the National Academy of Forensic Engineers, Volume
XXVI, No. 1, June 2009, 121-138.
- Li KW et al. Evaluation of two
models of a slipmeter. Safety
Science 47 (2009), 1434–1439.
Technical Report TR-A1264.3-2007, Using Variable Angle Tribometers
(VAT) for Measurement of the Slip Resistance of Walkway Surfaces.
American Society of Safety Engineers, Des Plaines IL, 2007.
KW et al. Friction measurements on three commonly used floors
a college campus under dry, wet, and sand-covered conditions. Safety Science 45
KW et al. Relationship between the measured friction
of floors on a horizontal surface and on a 10 degree ramp. International Journal of
Industrial Ergonomics 36 (2006), 705-711.
KW et al. Slips and Falls - Employee experience and
floor slipperiness: a field survey in fast-food restaurants. Professional Safety,
September 2006, 34-38.
F1677-05 (Withdrawn) Standard Test Method for Using a Portable
Inclineable Articulated Strut Slip Tester (PIAST) ASTM International,
West Conshohocken PA, 2005.
- Li KW et al. Floor
slipperiness measurement: friction coefficient, roughness of floors,
and subjective perception under spillage conditions. Safety Science 42
- Chang WR et al. The role of
friction in the measurement of slipperiness, Part 2: Survey of friction
measurement devices. Ergonomics,
2001, Volume 44, Number 13, 1233–1261.
- Chang WR, Matz S. The slip
resistance of common footwear materials measured with two
Ergonomics 32 (2001), 549–558.
- Chang WR. The effect of surface
roughness on the measurement of slip resistance. International Journal of
Industrial Ergonomics 24 (1999), 299-313.
Trust the tribometer used by insurance companies, major theme parks, test labs, cruise ship lines, and top forensic experts!