The pendulum CoF test (also known as the portable skid resistance tester, the British pendulum, and the TRRL pendulum) is the subject of a British Standard, BS 7976. The pendulum has been chosen by the Health & Safety Executive and the UK Slip Resistance Group as the recognised British Standard for measuring slip resistance. The pendulum has proved to give good correlation between its readings and the incidence of pedestrian slipping accidents and also produces the same hydraulic uplift characteristics that occur when a person slips.
Picture 1. British Pendulum Tester
This instrument, although often used in its current form to assess the skid resistance of roads, was originally designed to simulate the action of a slipping foot. The method is based on a swinging, imitation heel (using a standardised rubber soling sample), which sweeps over a set area of flooring in a controlled manner. The slipperiness of the flooring has a direct and measurable effect on the pendulum test value (PTV) given (previously known as the Slip Resistance Value).
The preparation of the standard rubber sliders is detailed in BS 7976 and the UKSRG guidelines. There is a small difference between the two methods of slider preparation, and in certain limited situations the two methods may give slightly different results. HSE and the UKSRG believe the changes in the latest version of the UKSRG guidelines (2005) are best practice. Oltco follow these guidlines.
Picture 2. Rubber Slider Preparation
Research has confirmed the pendulum to be a reliable and accurate test, leading to its adoption as the standard HSE test method for the assessment of floor slipperiness in dry and contaminated conditions. However, to use it reliably needs a suitably trained and competent person to operate it and to interpret the results (Oltco have been undertaking slip resistance testing for over seven years). The pendulum results should be interpreted using the information reproduced below.
Picture 3. Table of PTV Slip Potential Clasifications
Practical information generated by the pendulum using Slider 96 rubber, also known as Four S rubber (Standard Simulated Shoe Sole) is sufficient for assessing slipperiness in most circumstances. However, for assessing barefoot areas, unusually rough or profiled floors, the use of Slider 55 rubber, also known as TRRL rubber (a similar but softer, more malleable compound) may be advantageous. Although using the pendulum on heavily profiled flooring materials, stair treads and nosings is possible, doing so can be difficult, and should only be undertaken by experienced operators. Please contact Oltco for details.
Listed below is a link to the HSE STEP tool on the pendulum slip tester.
Picture 4. Link to HSE STEP tool