- why Slip Test?
- public space
- workplace
- who should be slip testing?
- the Slip Test process
- accreditation
- sample report
- links
Analysis of the slipDuring normal walking the most dangerous slips occur at the moment after the heel contacts the surface and weight is transferred downwards and forwards and the demand on slip resistance increases to a maximum. At this point the critical variables are the vertical force and its rate of increase, the strike angle the footwear makes with the surface and the speed of slip induced. Some researchers have indicated that slips without falls tend to occur after this initial phase and further into the stance phase. If someone knows a surface is slippery they often make adjustments to their gait which lowers the friction demand, hence the benefit, albeit limited, of warning signs, but where water or wet contaminants form a 'squeeze film' between shoe and floor the likelihood of slip is greatly increased. Latest research findingsThe Health and Safety Executive have confirmed they favour the measurement of the CoF, as set out by The UK Slip Resistance Group and in particular the dynamic coefficient (CoFd) of a surface material, using equipment such as the 'pendulum' slip resistance tester. The CoF measurement of vital slip resistance should test to a CoF of 0.36 or more on dry or wet surfaces. The slip co efficiency test has been identified as only one of a suite of measurements necessary to fully assess slip resistance. Using a skid tester is sometimes not sufficient and the use of a roughness transducer such as the Surtronic 3+ is required. Using a roughness meter such as the Surtronic on surfaces on which water or contaminants of known viscosity could foresee ably be present at a site, it is possible to assess the suitability of a surface material or finish. Increasingly manufacturers and suppliers will provide the results of this test information for their products in this way, the guidelines for obtaining these measurements have been produced by the UK Slip Resistance Group and are supported by the HSE. It is likely that these will form the basis for a new British Standard for the slip resistance of floors and finishes. The slip testThe Health and Safety Executive have confirmed they favour the measurement of the CoF, as set out by The UK Slip Resistance Group and in particular the dynamic coefficient (CoFd) of a surface material, using equipment such as the 'pendulum' slip resistance tester. The CoF measurement of vital slip resistance should test to a CoF of 0.36 or more on dry or wet surfaces. British Standards for Slip resistanceBS 5395 table 3, (shown below) gives performance indications for a number of different finishes for floors
The Roughness testUsing a roughness meter such as a Surtronic on surfaces on which water or contaminants of known viscosity could foresee ably be present at a site, it is possible to assess the suitability of a surface material or finish. |
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Roughness tests and requirementsThe level of surface roughness required to attain a direct contact between shoe and surface is also governed by the viscosity of any contaminant present and it is believed that larger sharper peaks of a micro surface can more readily 'breakthrough' a shoe-floor separating film. There are two main ways of expressing this characteristic of roughness. Firstly, Rtm values can be quoted which will allow a satisfactory CoF to be obtained given the viscosity of the contaminant, this parameter expressing roughness as measured peak-to-valley of the microsurface (see table). Secondly, Rpm, a mean of several separate maximum micro surface peak height measurements thought to be responsible for the bulk of frictional properties in wet conditions can also be determined. Rtm is easier to measure and is the most common measure of surface roughness, but Rpm Additionally, different relationships between CoF and Rpm exist for floors of differing hardness, harder flooring requiring greater peak roughness to achieve satisfactory slip resistance. The role played by drainage of contaminant or water via micro surface valleys is now thought to be of no great relevance in defining slip resistance, as it does not contribute to 'breakthrough'. The measure Rvm (roughness valley depth) has thus been devalued by this research. An approximate relationship between contaminant viscosity and the minimum value of Rtm roughness to achieve an acceptable CoF.
New Floors - the requirementsNew or replacement workplace flooring and flooring finishes must perform to a satisfactorily standard and must be able to cope with the numerous specific requirements of work activity that may include wheel loads, spillages, dust and dirt egress and possibly public access. Sometimes additional properties of noise attenuation, anti-tainting or the ability to dissipate static charge are necessary. The design process is structured around the principal requirements for some or all of the following:
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