Satra Technology Centre

Safetytread products are tested to ensure that they fulfil (and preferably surpass) the minimum quality requirements.

Safetytread employs the services of SATRA Technology Centre (SATRA), a research and technology centre, employing over 180 scientific, technical and support staff across two sites in the UK and China. Founded as the Shoe and Allied Trade Research Association in 1919, it has since extended its expertise to cover other consumer product industry sectors including furniture, safety products, clothing, floor coverings, leather goods and fabric care. It is partly funded through membership, which includes 1,600 companies in over 70 countries.

SATRA performed two separate assessments on Safetytread to test for slip resistance.

Pendulum Method

SATRA has conducted an assessment of the slip resistance of a sample of Safetytread flooring. The sample has demonstrated a low slip potential under both wet and dry test conditions when tested using BS7976-2:2002 Pendulum Method.

The method of test is intended to assess the potential of slipping for people walking on a flooring material. A pendulum attached to a spring loaded foot fitted with a standard rubber slider referenced Slider 96 is allowed to swing so the slider contacts a dry wet test flooring over a set distance. The extent to which the pendulum fails to reach its release height on the overswing is determined as a measurement of the slip resistance. The procedure is carried out in three directions, in one principal direction, at 90 degrees to this and at 45 degrees to the principle direction.

During the assessment the surface roughness meter (Surtronic 3+) travelled across the surface of the floor covering at ten different areas. The surface roughness meter travels over a 4mm distance and measures the maximum trough to peak height in five 0.8mm sections: the Surface Roughness Measurements (Rz) roughness is the average of the five rt values. The Safetytread sample average Roughness Measurement is 95.7Rz(PTV), which would suggest that the floor covering submitted for testing has a low slip potential in the wet conditions.

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London Underground Method

SATRA has conducted an assessment of the slip potential of a number of samples of Safetytread flooring. The samples have satisfied the requirements of London Underground E6464 A2 Engineering Standard – Rolling Stock Floor Coverings.

Section 8.4 (SATRA TM144) Slip Resistance of profiled floors stipulates that the coefficient of friction value must not fall below 0.40 for more than 290mm traverse, taking into account a representative cycle from the centre of a 100mm trace commencing after the first 20mm of movement in all directions under test.

The method of test is intended to assess the potential of slipping for people walking on a flooring material. It determines the coefficient of friction (CoF) between footwear outsoles and flooring surfaces under conditions simulating those experienced at the most critical parts of a typical walking step. in this instance a Rubber slider referenced Slider 96 (formally known as Four S Rubber) of diameter 76mm, is used to simulate a male shoe heel at the critical angle to the floor. testing has been carried out with the slider at an angle of 5 degrees to the flooring.

BS 8493

BS 8493:2008+A1:2010 – ‘Light Reflectance Value (LRV) of a surface – Method of test’, uses the CIE, x, y values measured under standard conditions, with a sphere-type spectrophotometer. This method will give an accurate value for the LRV of a material at the point at which it is measured. Hence, where a new material is measured, issues such as fading due to weathering or factors resulting from installation (such as lighting) will not be taken into account.

Within BS 8493:2008+A1:2010, the number of measurements taken for an individual specimen is dependent on the sample size. For general surfaces – including carpet specimens – this shall be at least 450mm x 450mm. The sample submitted is divided into a grid and measurements taken at each point where the grid lines cross. The grid and measurement points for a 450mm x 450mm sample are shown in figure 1 as an example.

BS 8493:2008+A1:2010 is applicable to opaque paints and coatings where the surface texture thickness is less than 2mm; opaque coverings such as flooring materials where the texture is less than 2mm; opaque materials such as metallic items where the texture is less than 2mm and opaque materials that have a non-opaque coating or covering (such as a varnish or clear lacquer). It can also be used with multi-coloured surfaces.

There are some instances where this method cannot be used, such as with photochromic and fluorescent materials.

Visual Assessment

It can be possible to use colour swatches with known light reflectance values to approximate a LRV for a material by visual assessment. This is done by simply placing the material in question against a range of materials until a best match is found. As with the use of hand-held devices, the lighting present when the assessment is carried out may have an influence on the results obtained, and so should be recorded. Visual assessment is often the least accurate of the methods described.

BS 8300:2009+A1:2010 also includes a table giving Light Reflectance Values for 100 of the 122 colours listed in BS 4800:2011 – ‘Schedule of paint colours for building purposes’, which can be useful for an initial selection of materials.

SATRA Light Reflectance Values (LRVs)

The way in which objects or the differences between surfaces are seen is an important factor when considering the fitting or furnishing of a building – especially as the needs of the visually impaired will need to be taken into account. Having a good contrast between surfaces and objects (such as doors, door handles, edges of stairs or where there is a change in gradient or surface of floors) can overcome issues that prevent people with a reduced level of eyesight from making full use of buildings and their surrounding (UK Building Regulations Approved Documents M:2013 – ‘Access to and use of buildings’).

For the visually impaired, it is often the amount of light that the surface or object reflects – the Light Reflectance Value (LRV) relative to its surroundings – that determines whether it can be seen or not. By measuring the LRV of different materials, fixtures and fittings, items can be chosen that give an acceptable contrast. The greater the difference between the LRV of adjacent materials, the more likely the difference in the surfaces will be identified.

BS 8300:2009+A1:2010 – ‘Design of buildings and their approaches to meet the needs of disabled people – Code of practice’ provides information on what may be considered as acceptable levels of contrast in light reflectance values.

Annex B of this document gives guidance on acceptable LRVs for a range of different situations. A difference of 30 points or more is considered as being good. However, a difference of 20 points or more may also be considered as acceptable – especially where the lighting is greater than 200 lux, or for large areas. Values of less than 20 are considered as being poor.

When deciding whether a contrast is acceptable or not, consideration also needs to be given on whether the objects are two or three-dimensional, shiny or matt, and metallic or non-metallic in nature. For instance, a door handle and door may be acceptable with a difference of only 15 points.

The higher the value obtained for LRV, the greater the amount of light that is being reflected. A value of 100 represents total reflectance of light by an object (therefore, it appears white) and 0 indicates total absorption of light (black).

A number of methods that may be used for determining LRV are also given in BS 8300:2009+A1:2010.

Hand-held Colorimeter

The use of a hand-held device for the calculation of approximate LRV values may be useful for onsite measurements. Where this is done, the lighting in place at the time measurements are taken may affect the results obtained. As such, details of lighting should be recorded along with the results for LRV. Colorimeters may also be suitable for metallic or glossy surfaces, or where the surfaces are curved.

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