ASTM Tribometer Standards

Slips, Trips and Falls

ASTM is the American Society for Testing and Materials, a nationally recognized consensus standards-making organization, active in the development of slip resistance related standards. Some methods are only approved for specific uses. For example, the standard for the horizontal dynamometer pullmeter method (ASTM C1028) specifies this device is approved only for use on ceramic tile. Using it to test walkway surfaces other than ceramic tile has no validity, since the device was only evaluated and approved for use on this specific material.

ASTM F13 TRIBOMETER STANDARDS

The title of the ASTM F-13 technical committee is Safety and Traction for Footwear. Its name is a bit misleading, since it's scope also includes safety and traction for walkway surfaces, as well as practices related to the prevention of slips and falls. F-13 is made up of several subcommittees, one of which is F13.10 Traction, which has jurisdiction over all tribometer standards. There are currently five (5) tribometers for which there is an F-13 standard.

the James Machine, a laboratory only device for dry testing only under standard F489, Standard Test method for Using a James Machine.

The James Machine has a several inherent biases, which prompted users of this instrument to make modifications to achieve good repeatability on a single instrument and good correlation between several machines. The device needs continuous maintenance and adjustment, in part due to the required release of an 80-pound weight.

As a laboratory-based machine, it can only be used on flooring materials, not floors. Since the device is subject to ' sticktion' , and it specifies the use of leather (whose properties change when wet, delivering overly-optimistic readings), this device can only be used to test dry surfaces. Set-up instructions have never been standardized, an issue made more complex by the presence of at least four different versions of the James Machine, none of which are still in production. Despite it's shortcomings, the device is still used to validate the merchantability of new flooring materials and treatments.

the Horizontal Pull Slipmeter, approved for dry testing only under standard F609, Standard Test Method for Using a Horizontal Pull Slipmeter (HPS).

Aside from the problem of 'sticktion ' that makes this device unreliable on wet surfaces, there are other concerns:

the use of a spring combined with the analog indicator makes it difficult to obtain a definitive reading;

the lack of structure between the motor and the meter/weight (a nylon string) results in potential operator variances in the application of lateral forces;

although there are devices based on similar dragsled technology, the ASTM approved version of the HPS is no longer in production.

the NBS-Brungraber (or Mark I), approved for dry testing only as the Portable Articulated Strut Tester (or PAST) under standard F1678, Standard Test Method for Using a Portable Articulated Strut Slip Tester. [NOT PICTURED]

Similar in principle to the James Machine, the Mark I is also an articulated strut instrument approved only for dry testing. The tester is generally used with a leather test pad. However, it is a portable device that can test actual floors, and uses a graduated rod that provides a direct reading from the device. Some calculation is required to convert this to a slip resistance measurement.

the Brungraber Mark II, approved for dry and wet testing as the Portable Inclineable Articulated Strut Tester (or PIAST) under standard F1677, Standard Test Method for Using a Portable Inclineable Articulated Strut Slip Tester.

A gravity-based articulated strut device designed to avoid the 'sticktion' problem, the Mark II enables users to reliably meter wet surfaces.

It uses a ten-pound weight on an inclineable frame, with a test foot suspended just above the walkway surface. Each time the angle is set to a more horizontal position the weight is released, until a slip occurs.

the English XL, approved for dry and wet testing as the Variable Incidence Tribometer (or VIT) under standard F1679, Standard Test Method for Using a Variable Incidence Tribometer.

In the early 1990's, William English developed the English XL, an articulated strut device similar in principle to the James Machine and the Mark II.

Unlike those devices, the English XL relies not on gravity, but is powered by a small carbon dioxide cartridge at a set pressure. This feature assures consistent operation by the application of uniform force for each test, and it permits reliable metering of inclined surfaces such as ramps.

Like the Mark II, the application of vertical and horizontal forces is simultaneous, thus avoiding residence-time and permitting reliable measurement of wet surfaces.

OTHER ASTM TRIBOMETER STANDARDS ( back to top)

Other standards relating to the measurement of pedestrian slip resistance are the responsibility of other ASTM committees. Except for C1028, each of these specify devices for which there is also an ASTM F-13 standard:

D2047, Standard Test Method for Static Coefficient of Friction of Polish-Coated Floor Surfaces as Measured by the James Machine is under the jurisdiction of technical committee D21 Polishes.

D5859, Standard Test Method for Determining the Traction of Footwear on Painted Surfaces Using the Variable Incidence Tester (VIT) has been transferred from D01 Paints to ASTM F-13;

F462, Standard Consumer Safety Specification for Slip-Resistant Bathing Facilities is the responsibility of technical committee F15 Consumer Products;

C1028, Standard Test Method for Determining the Static Coefficient of Friction of Ceramic Tile and Other Like Surfaces by the Horizontal Dynamometer Pull-Meter Method, under the jurisdiction of technical committee C21 Ceramic Tile.

C1028Dry Conditions Narrow.JPG

Although often confused with the F609 HPS device, this is a different instrument. A do-it-yourself instrument, the C1028 method consists of instructions on how to construct and operate the device, calling for an analog dynamometer, a Neolite™ test pad, and a 50-pound weight.

Because it is not a manufactured device, almost every unit made is different from another, increasing the potential for variability of results.

Although it is currently approved for wet testing, it has been long known that like other dragsled technologies, the C1028 method produces erratic results on wet surfaces.

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