Q: Does an R9/R10/R11/R12/R13 value equate to a PTV?
No. The difference in methods means that it is impossible to correlate DIN 51130 R values and BS 7976 PTV’s beyond, “A higher R value will usually mean a higher PTV”. The best way to determine a PTV for a surface with a given R value is to send us a small (300x300mm) sample which we can test in house quickly and inexpensively, providing an independent BS 7976-2 slip test report.
The DIN 51130 R value is generated using a test operator clad in safety footwear and oil as a contaminant. The BS 7976 Pendulum uses a smooth 4S (Standard Simulated Shoe Sole) rubber and less viscous water contamination. Ramp tests conducted using identical smooth 4S soles and water contamination (as per the HSE/HSL ramp test) show good correlation with Pendulum tests, as could be expected. However, the increased viscosity of oil contamination will serve to effectively reduce available grip, recorded CoDF and equivalent PTV, by an unknown amount. Conversely, the profiled safety footwear will serve to effectively increase available grip, recorded CoDF and equivalent PTV, again by an unknown amount.
It is a common mistake to assume that each floor surface has a CoDF (Coefficient of Dynamic Friction), ultimately describing how slippery it is, and indeed some websites offering advice on slip testing erroneously equate R values to PTV’s. CoDF describes the interaction between 2 specific surfaces however, and is further complicated by the inclusion of a lubricating film and, for the purposes of slip risk assessment, the biomechanical actions of a pedestrian losing balance. CoDF values produced by differing methods cannot generally be considered interchangeable as a result. It should be noted, when specifying floors, that any slip and fall accident is likely to be followed with a BS 7976-2 Pendulum test to determine if the surface is safe or slippery. On this basis the DIN 51130 R values should only be considered as a specified slip resistance for those surfaces which will be subject to highly viscous contamination and safety footwear in end use. The BS 7976-2 Pendulum remains the preferred slip test method of both the HSE and the UK Slip Resistance Group.
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