The dry floor friction tester is a machine which measures the slip resistance of floors in a dry condition. The most commonly used equipment for this type of test is known as the tortus.
This is aptly named due to the slow movement over the floor surface being tested. There have been three versions of the Tortus friction testing equipment, with MK 3 now being able to download data onto a memory stick to then be analysed in more detail later.
How does the dry slip testing equipment operate ?
The dry slip resistance testing equipment operates by measuring the force applied to a rubber slider as it is dragged along the floor. The slider is of a 9 mm diameter disk made of Slider 96 material and have a weight of approximately 200 grams. The Coefficient of Friction (CoF) which is what the dry FFT measures is a ratio of the horizontal force compared to the vertical weight of the slider as it moves along the floor; simple high school physics.
Prior to measuring the frictional properties of the floor surface, the slider is conditioned using P400 grade paper to provide consistency in the roughness of the test material. The machine is also corrected prior to measurements to account for the weight of the slider. This is also commonly referred as calibration.
The slip resting testing is conducted in dry conditions and the machine moves across the surface at a rate of about 1 meter per minute. The total distance travelled is 800 mm, being in line with the Australian Standard for dry slip resistance testing. Each 800 mm of travel is then further broken up into individual measurements of 100 mm to assess if some sections of the floor were found to obtain results lower than 0.40 or 0.35, depending on the slip testing standard.
Dry floor friction testing standards
The first Australian Standard for measuring the slip resistance of dry floor surface was AS 3661.1 Slip resistance of pedestrian surfaces – Requirements which was first introduced in 1993. This was to measure both new and existing surfaces, however AS 3661.1 was replaced partially in 1999 with the introduction of AS 4586 which was for new surfaces and then AS 3661.1 was available superseded after 2002 with the introduction of AS 4663 to measure the slip resistance of existing floor surfaces.
The test is portable and can be used for a variety of surfaces including stone, timber, vinyl & resilient material, concrete and the like. Many shopping centres conduct independent slip resistance testing services on a regularly basis. Commonly dry slip testing is conducted on a quarterly basis, every three months, unless the floor surface has been changed. These changes generally include the removal or additional of a floor polish.
Dry Floor Friction Slip Test Results
The results of slip testing generally rely on passing a threshold of 0.40, which has been accepted over the years as being suitable. While there has been a significant amount of research for the slip resistance ratings on water wet contaminated surfaces, there appears to be little evidence, if any that 0.40 is a suitable measure of acceptance. The new Australian Standards for slip testing previously provided a notional contribution of the risk of slipping when dry; however this notional basis of risk based on the slip test results has been removed and no alternative interpretation has been provided.
Until the new version of HB 197 is released, the value of 0.40 should be still used as the industry accepted value, however care should be taken when interpreting the independent slip testing results for any legal proceedings, particularly if one is asked to prove causation. Other incidents in dry conditions may be useful to identify this, however care must also be taken to remove confounding factors such as people stepping on foreign objects and the like, which is quite common in shopping centres.
How do I ensure that my test report is valid
Slip Check also provides third party calibration testing of slip testing equipment which is required to provide evidence that the machine is in good working order. When assessing the accuracy of slip resistance testing results, ensure that the independent slip testing services are NATA accredited such as Slip Check division of Safe Environments.
For more information on dry slip resistance testing and consulting services please contact our Sydney or Melbourne office on the number or email below.
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