Slip testing methods are important in assessing the slip resistance of surfaces and ensuring a safe environment compliant with UK Health & Safety law. Various testing methods are available, each with its advantages and limitations. This article aims to compare different slip testing methods commonly used in the UK, highlighting their characteristics, applicability, and considerations for accurate slip resistance assessment.
Pendulum Test
The pendulum test is one of the most widely recognised slip resistance testing methods in the UK. It measures the dynamic coefficient of friction (CoF) by simulating heel strikes on a surface. The pendulum test provides a single value that indicates slip resistance. It is highly regarded for its accuracy, reproducibility, and compliance with UK slip resistance standards, such as the HSE Guidelines and UK Slip Resistance Group (UKSRG) guidelines. This test is the most likely to be used in the event of a slip and fall injury claim reaching Court, and warrants selection for risk assessment based on this factor alone.
Tribometer Test
Tribometers are devices that measure slip resistance by evaluating the frictional force between a surface and a specified object, such as a rubber slider. Different types of tribometers, such as the Tortus, SlipAlert, Portable Skid Resistance Tester (PSRT or Pendulum), or Variable Incidence Tribometer (VIT), are available. Tribometer tests provide information on the frictional characteristics of surfaces and are suitable for laboratory and field testing. They can offer detailed data on slip resistance properties under various conditions, but care should be taken when interpreting results from a pedestrian’s standpoint.
Coefficient of Friction (CoF) Measurements
CoF measurements involve quantifying the frictional force between a surface and a standardised object, typically using a drag sled or a slip meter. These tests provide a numerical value representing the ratio of the horizontal force to the vertical force applied during the measurement. CoF measurements offer a straightforward and cost-effective approach to assessing slip resistance. However, they may not fully capture the complexities of slip behaviour in different scenarios. A Pendulum test will produce a CoF measurement in the same way as dragging a block over a surface might, but the results will not be comparable in contaminated conditions.
Considerations for Accurate Slip Resistance Assessment
- Several factors should be considered to ensure accurate slip resistance assessment regardless of the testing method used:
- Surface conditions: Test results can vary depending on surface conditions, such as cleanliness, moisture, or the presence of contaminants. Consistent and standardized surface preparation is essential to obtain reliable and comparable results.
- Surface characteristics: Different surface materials and textures can influence slip resistance. It is important to consider the type of surface being tested and select the appropriate testing method accordingly.
- Test environment: Slip resistance can be affected by environmental factors like temperature, humidity, and lighting. Test conditions should be controlled and standardized to ensure reliable and comparable results.
- Test location and relevance: The slip resistance requirements may differ depending on the specific application or location being assessed. Consider the context and relevant standards or guidelines for accurate interpretation and compliance.
- Interpretation of results: Whilst quantifying grip is a valuable tool, the ultimate aim will usually be quantifying the risk of a pedestrian slip. Not all CoF measurements are equal or interchangeable, so using a method that replicates a pedestrian’s heel slip motion (a Pendulum test for instance) is likely to provide a better indicator of slip risk.
