There are many different measures of slip risk

The ones you need to know about:

• Coefficient of Friction (CoF)

• Pendulum Test Values (PTV)

• R Numbers (German Ramp)

• SlipAlert Test Values (STV)

SlipAlert test Values convert easily to PTV or Cof. Beware, there are test machines that claim to measure CoF but fail to account for the effcets of water or contamination.

Coefficient of Friction... µ

The physics of slip resistance is simple in theory... µ = H/V i.e. coefficient of friction is the Horizontal Force divided by the Vertical Force.

Hydrodynamic Squeeze Film

Rubber or plastic heels defy the simple physics. The addition of water or other contamination make it more complicated. Water can form a “squeeze film” that creates a lift effect like aqua-planing.

Pendulum Test Values (PTV or British Pendulum Number BPN)

The Pendulum was invented in 1930 in America. Also known as the British Pendulum or TRL Pendulum because it was adopted by the Transport Research Laboratory as a skid tester. Until the invention of SlipAlert, the Pendulum was the only device to re-create the squeeze film effect required to measure wet slip risk.

Confusing Slip Measures

Be wary of slip risk measures that you cannot easily verify, and inaccurate “trundle test” measures. R numbers range from R9 (lowest score) to R 14

Different Shoe Heels and Bare Feet

• Slips usually occur at heel strike

• Test using hard or soft rubber as appropriate

• TRL (soft) rubber simulates bare foot slipping

SlipAlert accurately simulates a pedestrian slip

• SlipAlert travels at least the length of slip, and simulates the range of speed during a pedestrian slip

• As in a pedestrian slip, SlipAlert exerts a consistent down force

• SlipAlert correlates with the Pendulum and mirrors real slip experience on all floor surfaces

SlipAlert floor testing is fast and flexible

• Test many locations, different directions, test wet, dry, dusty, and “as found” conditions

• Look for variation caused by areas of wear/contamination

• Test the floor with both soft and hard rubber sliders especially for floors with barefoot users

Re-testing and Monitoring change

• Re-test floors periodically to see if there is any change, and re-test if there is a reported slip accident.

• Re-test whenever there is a change made to the floor, it’s use, or the cleaning regime.