AS/NZS 4586 ‘Slip resistance classification of pedestrian surface materials’ outlines four test methods to classify and assess the frictional properties of floor surfaces. Safe Environments discuss the following Australian slip test methods:
- Wet Pendulum Slip Test
- Dry Floor Friction Slip Test
- Wet Barefoot Ramp Slip Test
- Oil Wet Ramp Slip Test
Wet Pendulum Slip Test
The wet pendulum slip test (AS/NZS 4586 Appendix A)is conducted using a Wessex or Munro - Stanley London Pendulum Slip Tester. This pendulum device is portable and consists of a weighted foot with a test slider that swings down and slides across the surface wetted with water. The weighted foot comprises a spring loaded rubber test slider that exerts a prescribed force over the specimen as it slides across the surface. The results are expressed as a British Pendulum Number (BPN) and classified according to AS/NZS 4586 as Z, Y, X, W or V.AS/NZS 4586 classifies the surface based on the mean BPN where the Australian Standard for onsite slip testing AS/NZS 4663 expresses the result in terms of BPN. AS/NZS 4663 also provides a notional contribution of the floor surface to the risk of slipping when water wet based on the BPN.
While there are 2 rubber slider materials that may be used, Four S (simulated standard shoe sole) is generally accepted as the material to assess the slip resistance for the public wearing suitable footwear. TRL (Transport Research Laboratory) rubber is used for highly slip resistant and profiled surfaces. TRL rubber may provide a better indication of barefoot slip resistance due to the softer yielding nature of the material.
Dry Floor Friction Slip Test
The dry floor friction slip test (AS/NZS 4586 Appendix B) uses a battery operated machine known as the dry FFT or Tortus. The dry FFT measures the force opposing the motion of a test slider of Four S rubber as it moves across the surfaces at a slow constant speed. The average of two measurements over a certain distance is taken and the results are expressed as Coefficient of Friction (CoF). The coefficient of friction is a ratio of the horizontal and vertical force. The test results when tested to AS 4586 are classified as either G or F.
Wet Barefoot Ramp Slip Test
The wet barefoot ramp slip test (AS/NZS 4586 Appendix C)uses a panel of the test surface which is constructed on a ramp. Two test people attach themselves to a safety harness, after bathing their feet for 10 minutes to soften the skin, walk bare foot on the test surface while the angle of the platform is increased until the limit of safe walking is achieved. This is generally when the test walker slips or feels that they will slip on the board. The angle that the limit of safe walking is obtained is known as the mean angle of inclination. Three calibration boards A, B & C are also slip tested, with the classification of the test panel based on the mean angle of inclination obtained in comparison with the calibration boards to give an A, B or C ramp rating according to AS 4586.
Oil Wet Ramp Slip Test
In the oil wet ramp slip test, or r rating slip test (AS/NZS 4586 Appendix D),an amount of motor oil is placed on the test surface and the two test persons wear safety boots. Three calibration boards are walked on in a similar manner to the wet barefoot ramp slip test. These calibration boards are then used to provide a correction factor to standardise the walkers. The slip test classification is determined by the mean angle of inclination achieved and a correction factor based on the angle of inclination of the 3 calibration panels and provides an R9, R10, R11, R12 or R13 slip rating.