What do PTV, SRV, R value, Rz, CoDF, A B C classification, mean?
PTV – Pendulum Test Value
The number produced by Pendulum testing, primarily but not limited to BS 7976-2. Values above 35 are classified as a low risk of slip. Values from 25 to 35 inclusive are classified as a moderate risk of slip. Values below 25 are classified as a high risk of slip.
SRV – Slip Resistance Value
The same as PTV, it is simply an older reference to the same.
R value – A classification from DIN 51130 ramp testing.
The classification is based on the angle at which a slip occurs when gradually inclining a test sample and ranges from R9 to R13. The test uses safety footwear and oil contamination and classifications span accepted risk categories so its usefulness is limited. It remains a popular way for manufacturers to classify floors however, as the lowest slip resistance classification, R9, can be misconstrued as offering satisfactory slip resistance.
Rz – A specific parameter of the surface roughness of a material.
Rz describes the mean vertical displacement of the test stylus as it is dragged across a horizontal sample. The value is often erroneously used as a measure of slip resistance, a purpose for which it is extremely unreliable. The Rz value fails to take into account the shape or density of the micro-profile, which can have a significant impact on slip resistance.
CoDF – Coefficient of Dynamic Friction
The true base description of slip resistance, CoDF values can be misleading as their accuracy depends entirely on the method used to produce them. A mass can be dragged across a floor surface and the force required to move it measured in order to produce a CoDF, in terms of pedestrian slip testing however, the value produced would be of little relevance to the heel strike and lubricating film mechanics of a real slip and so a poor indicator of pedestrian slip resistance.
A B C classifications – A classification from DIN 51097 ramp testing.
The classification is based on the angle at which a slip occurs when gradually inclining a test sample and ranges from 12° (A) to >23° (C). The method uses bare feet and soapy contamination, making it a valuable method for the assessment of products destined for wet leisure environments.
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