English XL Research Articles

Evaluating the Slip Resistance of Various Walkway Surface Contaminants

For decades, falls have been a leading cause of preventable injury and death in the United States. Slip and falls, which are often caused by a contaminant(s) on the walkway, are one of the most prevalent types of falls in several industries. There were two main purposes of this study. The first was to evaluate whether the English XL Tribometer could reliably measure the slip resistance of contaminants other than liquids, including semi-liquids and dry goods. The second purpose was to evaluate the slip resistance properties of various walkway surface contaminants on different types of flooring surfaces using an English XL Tribometer. The findings showed that the English XL Tribometer is capable of reliably measuring the slip resistance of surfaces when they are contaminated with not only liquids, but also semi-liquids and dry goods. The findings also showed that surfaces that were slippery and hazardous for pedestrians when contaminated with water became even more slippery when contaminated with other contaminants such as common beverages, condiments, personal cleaning products, and various dry goods like sugar, cornmeal, and oats. The findings also indicated that even surfaces that were “slip resistant” and “safe” when wet with water can become slippery and hazardous for pedestrians when contaminated with more viscous contaminants such as condiments and personal cleaning products, along with dry goods like sugar, cornmeal, and oats.

Slip Resistance Evaluation of 10 Indoor Floor Surfaces

Slip and fall injuries and fatalities continue to be a significant problem at work and in the community. Water is the most common contaminant that reduces traction on floors and other walkway surfaces resulting in a slip and fall event. This project investigated 10 common flooring surfaces to assess their slip resistance when dry vs wet and coated vs uncoated. Investigators used the English XL Variable Incidence Tribometer to measure slip resistance under all conditions. Results revealed a significant (p - value < 0.05) loss of slip resistance when wet vs dry. Investigators also found significant (p - value < 0.05) increases in traction when using a coating under wet conditions. Researchers support the use of coatings for floors and walkway surfaces that increase traction and reduce the chances of slip and fall events under all conditions.

Contaminant film thickness affects walkway friction measurements.

Walkway tribometers are used to measure available friction for evaluating walkway safety and pedestrian slip risk. Numerous variables can affect tribometer measurements, including the type and distribution of contaminants on the surface. Here, we quantified the effect of application method on contaminant film thickness, and the effect of film thickness on tribometer measurements on the four reference walkway surfaces used in ASTM F2508-16e. Distilled water, 0.05% sodium lauryl sulfate (SLS) solution, and 0.04% Triton X-100 solution were poured, squirted, and sprayed onto the surfaces to quantify their naturally occurring film thicknesses. These application methods had a significant effect on the resulting film thickness (p < 0.038), with the pour method consistently generating the thickest films and the spray method generating the thinnest films. We then quantified the effect of film thickness for the three contaminants (thickness range 0.3–3.3 mm) on the friction measurements of three common tribometers (Mark IIIB, English XL, and BOT 3000E) on each reference surface. A separate ANOVA was used for each of the 3 × 4 × 3 = 36 combinations of tribometer, surface, and contaminant. Friction measured with the Mark IIIB decreased with increasing film thickness on one surface across all three contaminants and on a second surface with the SLS contaminant. Friction measured with the BOT 3000E was sensitive to film thickness on two surfaces with water and one surface with Triton. The XL was unaffected by contaminant film thickness. Overall, despite significant differences in film thickness with contaminant application method, friction measurements were either insensitive to film thickness or varied only a small amount in all cases except for the Mark IIIB on the roughest surface. Film thickness did not alter the relative slip resistance of the four ASTM F2508 reference surfaces.

Quantifying the uncertainty in tribometer measurements on walkway surfaces

Properly estimating and reporting the uncertainty of walkway surface friction is key to ensuring pedestrian safety. Here we quantified the amount and sources of uncertainty in friction measurements by having four users of four units of each of two walkway tribometer models (Slip-Test Mark IIIB, English XL) perform 12 measurements on four samples of four different surfaces that ranged from slippery to slip-resistant. We found that 51–82% of the total variance in the measurements was explained by the user, unit, sample and a user–unit interaction, which means that the variance a single user calculates from their own data does not capture most of the uncertainty in their measurements. Based on these data, the minimum uncertainty associated with the mean of a user’s measurements is ±0.064 (Mark IIIB) and ±0.072 (XL) to be 95% confident that their mean captures a surface’s available friction. Practitioner Summary: Walkway surface friction measurements are less accurate than they appear. Based on an experiment quantifying the amount and sources of uncertainty in surface friction measurements using two common tribometers, we quantified and report the minimum uncertainty that users can assign to their walkway surface friction measurements. Abbreviations: ANOVA: analysis of variance; ANSI: American National Standards Institute; CI: confidence interval; E: east; ILS: interlaboratory study; ISO: International Standards Organization; JCGM: joint committee for guides in metrology; N: north; S: south; SBR: styrene-butadiene rubber; SD: standard deviation; TR: test result; W: west

A Comparison of the ASTM F2508 and ANSI/NFSI B101.3 Walkway-Safety Tribometry Standards Using Measurements from Two Different Tribometers

Abstract In order to provide the safest possible built environment for pedestrian use, care must be taken to supply walking surfaces that are slip resistant. However, there remains an inability to establish a method of consensus for determining whether a surface is slip resistant. Two current walkway-safety standards illustrate two different approaches to this issue—ANSI A137.1, American National Standards Specifications for Ceramic Tile, and ANSI/NFSI B101.3, Test Method for Measuring Wet DCOF of Common Hard-Surface Floor Materials, promotes a numeric threshold model, while ASTM F2508, Standard Practice for Validation, Calibration, and Certification of Walkway Tribometers Using Reference Surfaces, is a validation standard based on the relative ranking of walkway surface materials. The goal of this study was to determine whether these two standards are compatible in how they rank/evaluate surfaces. To do this, two tribometers, (the BOT-3000E (BOT) (Regan Scientific Instruments, Southlake, TX, USA) and English XL Variable Incidence Tribometer (XL) (Excel Tribometers, Chesapeake, VA, USA)) were used to take slip resistance measurements using the four reference surfaces designated in the ASTM F2508 standard. Measurements for the BOT were taken under three conditions: (1) styrene–butadiene–rubber (SBR) test foot with distilled water and surfactant (consistent with ANSI/NFSI B101.3), (2) SBR test foot with distilled water, and (3) Neolite test foot with distilled water. Measurements for the XL were taken using a Neolite test foot with distilled water. Results indicate that the vinyl composite tile was the reference surface nearest to the ANSI threshold for high slip resistance but fell approximately 11 % below the threshold value of 0.42. The two most slippery reference surfaces (granite and porcelain) fell well below the ANSI threshold for high slip resistance, while the most slip resistant (ceramic tile) was well above the threshold. Unexpectedly, we also found a strong linear correlation (R2 = 0.99) between the measurements from the XL versus the BOT with SBR and surfactant test condition, which allowed for conversion of slip resistance readings between the two tribometers under these conditions. These results provide new data that allow aspects of the ASTM and ANSI standards to be directly compared.

Development of a Slip Hazard: Partially Wetted Floors and Film Formation

Abstract Slip and fall hazards on wetted surfaces represent a substantial safety concern both in the home and workplace. In the presence of liquid contaminants, the hazards associated with potential slip and fall accidents are greatly increased. However, it is unclear at what point a partially wetted floor transitions from being a slip-resistant surface to a slip hazard. The presented work examines the relationship between film formation and slip hazards on flooring surfaces. First, a theoretical model was developed to predict the approximate onset of film formation for liquid droplets deposited uniformly across a surface. Then, the slip hazard of wetted flooring samples at various liquid contaminant surface densities was determined using a British Pendulum skid tester and an English XL tribometer. These experimental results were then compared with the theoretical model in an effort to further understand the role film formation plays in forming slip hazards on partially wetted floors. Using the combined approach, the minimum surface density loading required for a potential slip and fall hazard on a partially wetted surface was determined. This threshold value can inform safety professions of the potential injury risk of floors as they transition between dry to wet conditions.

표준 바닥재를 이용한 미끄럼 측정기의 검증방법 개선 및 활용방안

Department of Safety Research, Occupational Safety and Health Research Institute, KOSHA(Received June 11, 2013 / Accepted October 1, 2013)Abstract : The purpose of this study was to evaluate three kinds of slipmeters (BOT, BPT, English XL) used on-site floor with ASTM F2508 which is comprised of four different standard surfaces(polished granite, glazed porcelain, vinyl composite tile ;VCT, and ceramic tile). ASTM F2508 has two criteria that decide which slipmeter is appropriate or not. The evaluated slipmeters were dreg sled, articulated sturt, and pendulum strike type. The test results revealed that two kinds of slipmeters(BOT, BPT) successfully ranked all four standard surfaces and differentiated among standard surfaces with varying degrees of slipperiness. Nevertheless, the measured value with BOT on the VCT ,which was reported as slippery floor in previous study, was higher than its threshold(0.6). Although some slipmeter satisfy two criteria of ASTM F2508, they can underestimate the slip potential. So, another criteria is needed so as to reduce this problem. English XL couldn't properly measure slipperiness under the two kind of floors(glazed porcelain, VCT). So the slider of English XL was modified in order to meet two criteria of ASTM F2508. Key Words : slipmeter, validation, ASTM 2508-11, reference surfaces

Comparison of Three Different Slip Meters under Various Contaminated Conditions

ObjectivesTo challenge the problem of slipperiness, various slipmeters have been developed to assess slip hazard. The performance of in-situ slipmeter is, however, still unclear under the various floor conditions. The main objectives of this study were to evaluate the performance of three kinds of slipmeters under real conditions, and to find their dynamic and kinematic characteristics, which were compared with gait test results.MethodsFour common restaurant floor materials were tested under five contaminants. Slipmeters and human gaits were measured by high speed camera and force plate to find and compare their dynamic and kinematic characteristics.ResultsThe contact pressures and built-up ratio were below those of subjects. The sliding velocity of British Pendulum Tester was above those of subjects, while those of BOT-3000 and English XL were below those of subjects. From the three meters, the English XL showed the highest overall correlation coefficient (r = 0.964) between slip index and Ra, while the rest did not show statistical significance with surface roughness parameters (Ra, Rz). The English XL only showed statistical significance (p < 0.01) between slip index and contaminants. The static coefficient of friction obtained with the BOT-3000 showed good consistency and repeatability (CV < 0.1) as compared to the results for the BPT (CV > 0.2) and English XL (CV < 0.2).ConclusionIt is unclear whether surface roughness can be a reliable and objective indicator of the friction coefficient under real floor conditions, and the viscosity of contaminants can affect the friction coefficient of the same floors. Therefore, to evaluate slipperiness, the performance of the slipmeters needed to improve.

Methodological Considerations for Using the English XL Tribometer for Post Hoc Slip-and-Fall Evaluations

We examined several variables that can affect slip-resistance measurements obtained using the English XL tribometer to illustrate the importance of implementing the proper controls when using the device to evaluate a slip-and-fall incident. We measured slip resistance at two different locations on the same surface, under wet and dry conditions, with the tribometer oriented in eight different directions per location. Our results showed that location, direction, and surface wetness can affect slip resistance measurements, but the effects interact with each other in unpredictable ways. Discussion focuses on the importance of considering direction as well as location of a particular slip-and-fall, rather than strict adherence to ASTM F1679–04: Standard Test Method for Using a Variable Incidence Tribometer (VIT). We conclude that it is important to consider both location and direction when using the tribometer in analysis of any specific incident occurring on non-uniform surfaces.

Field evaluation of two commonly used slipmeters

A variety of slipmeters have been used to assess the slipperiness of floor surfaces. International standards for the operation of slipmeters describe the protocol for a single measurement. These standards usually do not cover some of the critical elements in safety assessment such as methods for the selection of measurement locations and the necessary number of repeated measurements at each location. Furthermore, most of the slipmeters were evaluated in laboratory settings with new floor surfaces and artificial contaminants. Two commonly used slipmeters, the Brungraber Mark II and the English XL, were evaluated at actual worksites in this experiment. Four floor tiles in each of four different work areas in the kitchens of 18 fast food restaurants were selected for repeated measurements with these two slipmeters. The results indicated that sanding of footwear materials has a significant effect on the outcomes of friction measurements, and the tile-to-tile variations in friction in the same areas of restaurants were also mostly statistically significant. Significant local variation in friction among tiles in the same area could potentially increase the chances of slip and fall incidents. Both slipmeters used in this experiment could potentially have problems in the areas with grease, such as grill and fryer areas, since the build-up of grease during repeated strikes could alter the outcome of friction measured.

The effects of slip criterion and time on friction measurements

Different institutions reported different results for friction measurements of identical material combination and surface conditions using identical slipmeters. The objective of this study was to evaluate three factors, slip criterion, sample, and time, that could contribute to such differences with two commonly used slipmeters, the Brungraber Mark II and the English XL. Friction between 16 commonly used footwear materials and three floor materials was measured under four surface conditions with two slip criteria at the interface. Some of the measurements were repeated at a different time. The results indicated that variations due to different samples were probably the smallest statistically among the three factors evaluated. The effect of slip criterion on friction coefficient could be quite significant compared with the effect of time for some material combinations and surface conditions. A more consistent slip criterion could potentially reduce the differences significantly in the results reported among different institutions.

The slip resistance of common footwear materials measured with two slipmeters

The slip resistance of 16 commonly used footwear materials was measured with the Brungraber Mark II and the English XL on 3 floor surfaces under surface conditions of dry, wet, oily and oily wet. Three samples were used for each material combination and surface condition. The results of a one way ANOVA analysis indicated that the differences among different samples were statistically significant for a large number of material combinations and surface conditions. The results indicated that the ranking of materials based on their slip resistance values depends highly on the slipmeters, floor surfaces and surface conditions. For contaminated surfaces including wet, oily and oily wet surfaces, the slip resistance obtained with the English XL was usually higher than that measured with the Brungraber Mark II. The correlation coefficients between the slip resistance obtained with these two slipmeters calculated for different surface conditions indicated a strong correlation with statistical significance.

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