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Using EN 511 to assess gloves to protect against the cold
Examining European standards covering gloves designed for use in cold environments, and the associated test procedures.
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Hands are an important part of our anatomy, and are critical for virtually every activity – from driving a vehicle to operating a keyboard. However, the uses to which we put our hands mean that they are frequently exposed to the risk of injury. Furthermore, as one of the extremities of the body, our hands are also particularly vulnerable to hostile environments such as cold climates. It can be difficult or impossible to remove the hazard and, therefore, it is often more practical to provide some form of hand protection.
Gloves are available that can protect hands and forearms from cuts, abrasions, burns, cold, puncture wounds, vibration, skin contact with hazardous chemicals and some electrical shocks. The nature of the hazard, the associated risk and the type of operation involved will affect the selection of gloves. It is essential that gloves are chosen that are designed for the specific application. Gloves designed to protect against one hazard may not protect against a different one, even though they may appear similar.
Regulation (EU) 2016/425
In Europe, items worn or held to provide protection fall within the scope of the Personal Protective Equipment (PPE) Regulation. These cover a broad range of products and hazards, and include different procedures to be followed by the manufacturer, depending on the severity of the hazard. For instance, it would be unreasonable to expect gardening gloves to be subject to the same level of scrutiny as those designed to protect wearers against dangerous chemicals or high voltages. A Notified Body such as SATRA must assess initial samples of such high-performance gloves or those intended to protect against the cold, in addition to associated documentation.
European Harmonised Standards
The PPE Regulation includes health and safety requirements that need to be taken into account for all types of PPE, but they do not describe or detail how particular types of product need to be tested. To support this regulation, the European Union Commission has mandated the development of various product safety standards via the European Standards agency CEN (Comité Européen de Normalisation). CEN has convened a technical committee working group (referenced CEN/TC 162/WG8) in order to develop a series of harmonised European standards to be used in the testing and certification of hand protection.
Heat loss from the hands can be via one of several mechanisms. The dominant ones are ‘conduction’ (heat transfer when the glove is in contact with a cold object – for example, something being held) and ‘convection’ (heat loss into the surrounding atmosphere, which will be highly dependent on movement of the surrounding air).
To assess the performance of a glove’s protection to the hands against cold hazards, there is a European standard referenced EN 511:2006 which includes a range of tests. Firstly, it includes requirements to assess the physical characteristics of the glove – such as its resistance to abrasion and tearing, which is based on EN 388 plus general requirements from EN 420. Both of these standards are covered in other Spotlight articles. In terms of temperature related characteristics, there are tests to assess resistance to flexing for gloves produced from coated materials or gloves intended to offer protection below -30ºC.
For protection against the cold, two tests are described, one for contact cold and one for convective cold. The contact cold test involves the glove materials being placed between metal plates which are at different temperatures. The measured temperature drop across the test specimen is used to calculate its thermal resistance. Figure 1 shows the SATRA cold contact test equipment. The convective cold test is a more complex procedure. The apparatus required for this latter test includes a heated hand in an environmental chamber that is set to a temperature at least 20ºC below that of the heated hand, and has a defined air flow rate. The principle of the assessment is to determine the electrical power required to maintain a constant temperature gradient between the surface of the heated hand and the atmosphere within the environmental chamber. The more electrical power that is required, the lower the thermal insulation value of the glove. This moulded hand as used by SATRA includes an embedded heater and sensing cables that have been manually wound round the palm and fingers without crossing over. Figure 2 shows a glove being assessed on the SATRA heated hand inside the environmental chamber.
To conclude, while hand injuries still form a high percentage of accidents, both at work and at home, many of them are easily preventable by wearing appropriate protective gloves. Increasing legislation and obligations on employers and manufacturers to provide safety equipment that offers adequate protection against a variety of hazards means that advances in material technology are continually under development. This will provide higher protection, better designed and more comfortable gloves which, if used more widely, should lead to a reduction in injury statistics.
Further information on SATRA's PPE certification and testing services is available at www.satra.com/ppe
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