How the pendulum works, and what a PTV means.

The pendulum — sometimes called the TRL pendulum — is a portable instrument that swings a weighted arm tipped with a rubber slider across the floor. The grip of the surface robs the swing of momentum, and that loss is read on the dial as a Pendulum Test Value (PTV). A higher PTV means more available friction and a safer floor.

Why this test, and not another

It is the method set out in BS 7976-2 and BS EN 16165, and the one the HSE names as its preferred approach for assessing both new floors and floors after an accident. By mimicking a heel strike it reflects genuine slipping far better than how a surface feels underfoot.

Wet, dry, and three ways

Each area is tested in three directions and, above all, in the wet — because that is when a floor turns dangerous. Recording along, across and diagonally to the line of travel captures any directional grain or wear in the surface.

Two rubber sliders

For everyday shod areas we use the Slider 96 (4S); for barefoot zones such as pool surrounds, showers and changing rooms we switch to the Slider 55. Both can be used together on heavily profiled surfaces.

Microroughness, where it helps

On water-wetted floors we can add a surface microroughness reading (in microns), which the HSE treats as a useful companion to the pendulum and a further line of evidence.