Scope
This section covers the procedure for the on site measurement of slip resistance of floors and flooring materials used by pedestrians. This procedure may not be appropriate for all sports surfaces, those used by vehicular traffic or surfaces with a gross profile comparable in dimensions with those of the Rubber Slider.
The main parameters of consideration are the friction in wet or contaminated conditions between the Rubber Slider and the floor surface and the roughness of the flooring material. The methods described apply only to horizontal floors that are approximately flat, and are not recommended for ramps or steps.
Selection of a Test Site Allowance for surface texture or where there is a slight run-off in level is made by taking measurements in three different directions – see diagram. Profiled or uneven floors often present a problem and, in certain instances, an unrealistic slip resistance value may be recorded. In all cases it is imperative that proper contact between the working edge of the Rubber Slider and the test surface are maintained throughout the contact length.
A wide variety of conditions of use should be included. For example, a doorway subjected to heavy traffic, an area close to a source of contamination, such as a vending machine, and finally, a little used area in a corner or behind a door.
If there has been an accident, then results relating to the accident site are best obtained within as short a time as possible, and preferably before any cleaning has been carried out. Where this is not possible, it must be clearly stated in the report that conditions at the test site may not be the same as those which existed at the time of the accident.
Test Areas At least six test areas 150 mm x 100 mm or greater are required to accommodate wet and dry measurements. Note : Each test area should be used only once.
Roughness Measurements Surface roughness can bring about an improvement in slip resistance in wet conditions. Irregularities can break up a water film, establishing contact with the shoe sole or heel. In this regard peaks are more helpful than troughs. The measurement of the various aspects of surface roughness is complex, but it has been established empirically that a measure of peak to trough roughness, Rz, is itself a useful guide to slip resistance.
Research has suggested that hard floors need to have a higher Rz roughness than polymeric floors for the same degree of safety in wet conditions, but whatever flooring material is used an Rz roughness value of at least 10 µm is needed. In circumstances where wetness is normal or expected, this figure may need to be significantly increased. High Slip Resistance Tester and roughness readings generally indicate a satisfactory floor. Conversely, low Slip Resistance Tester and roughness readings, indicate an unsatisfactory floor when wet. To allow for surface texture, measurements are taken in three different directions.
Profiled Floors Floor surfaces intended for installation in wet areas, such as swimming pool surrounds or floors intended for use in heavily contaminated areas are often profiled. The profiling serves two purposes, firstly it helps to drain water away and secondly, it enables soft shoe sole/heel materials or bare feet to deform and obtain a better grip.
While, in general, profiled floors in wet or contaminated conditions are safer than flat floors, this is not universally the case. Some profiled floors with rounded corners on the profiling and no degree of surface roughness can be very slippery in wet conditions.
Direct measurement of friction on profiled surfaces is more difficult than on flat surfaces. Results depend on the size of the raised profile areas and the ratio of high to low areas (distance apart of raised blocks).
Sliders Two types of Rubber Slider are available for testing surfaces using the Main Graduated Scale. The TRL (Transport Research Laboratory) Rubber Slider is commonly used on surfaces where the general roughness is greater than that normally found with internal flooring situations. For testing most internal flooring materials, those with a roughness of less than 15µm Rz, then it is customary to use the Four S (Standard Simulated Shoe Sole) Rubber Slider. We strongly recommend that you consult the applicable standard before choosing a Rubber Slider.