Why should you use PTV instead of R ratings?

In the UK, the HSE’s slip testing method of choice is the Pendulum.

This measures the dynamic co-efficient of friction provided by a floor surface, illustrated by a Pendulum Test Value (PTV).

Over the last decade, the UK market has become increasingly familiar with the Pendulum Test, but many specifiers, suppliers and purchasers of floors, however, talk about R Ratings when specifying floors for shod environments. What are R Ratings and why should you avoid them?

The R Rating comes from a German test, which uses a ramp to asses at which angle of slope a surface becomes slippery. It is a European standard, not recognised in the UK courts. It gives a range of slip resistance rather than a precise measurement.

R Rating Wet PTV range Slip potential range Accident risk exposure range
R9 11 to 18 High 1 in 2
R10 18 to 34 High to Moderate 1 in 2 to 1 in 100,000
R11 34 to 51 Moderate to Low 1 in 100,000 to significantly less than 1 in 1,000,000
R12 51+ Low Significantly less than 1 in 1,000,000
R13 71+ Low Very significantly less than 1
in 1,000,000

As you can see from the above, there are all sorts of potential pitfalls if you rely on an R Rating to choose a floor. For example:

  • R9 floors are often – totally incorrectly – chosen because “if they have an anti-slip rating they must be anti-slip”. Firstly, there is nothing below R9 – a common misconception. Secondly, as you can see, an R9 surface is a slip accident waiting to happen if the floor gets wet or contaminated.
  • R10 presents perhaps the biggest challenge because if you have an R10 floor you might have something pretty slip resistant, or something pretty slippery. And how do you know if the only information you have is the rating?
  • Even R11 might not quite be good enough for what you need if you have a foreseeably wet environment.
  • Once you get up the scale, in order to achieve an R12 or R13 Rating, a surface is almost certainly heavily textured. This will lead to cleaning and maintenance issues – and if a surface becomes contaminated then it can and will eventually become slippery.

Furthermore, the R Rating can only tell you about the out of the box slip resistance of a surface. Once laid on a floor in a real-life environment, the slip resistance can be very different to that achieved out of the box. This could be for a variety of reasons including the installation process, cleaning and maintenance, and wear. A Pendulum, conversely, can be used to test both out of the box samples an insitu floors.

Finally, and perhaps most essentially, if you were ever in the unfortunate position of being in court as a result of a slip accident and tried to rely on R Ratings, experience tells me that you would be in a very challenging position.

Overall, then, in the case of floor specification, 3 letters are better than one: PTV > R.

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