¹ ATEX - The abbreviation derives from ATmosphères EXplosibles . ² Directive 94/9/EC on equipment and protective systems intended for use in potentially explosive atmospheres. ³ A new ATEX Directive 2014/34/EU on the harmonisation of the laws of the Member States relating to equipment and protective systems intended for use in potentially explosive atmos-
pheres will be applicable from 20 April 2016. 4 Directive 99/92/EC Minimum requirements for improving the safety and health protection of workers potentially atr isk from explosive atmospheres. 5 EN 1149 - 5:2008 Protective clothing with electrostatic properties.
ANTISTATIC CERTIFICATIONS In order to compare antistatic properties of chemical protective clothing on a standardised level, there are several norms which manufacturers can use. With such norms the surface resistance and the charge-decay properties of fabrics can be measured and/or assessed. The surface resistance is covered by EN 1149-1 and the charge-decay is covered by EN 1149-3. EN 1149-1 is mostly used for ﬁ nished fabrics, whereas EN 1149-3 is used when surface resistivity can not be used because the dissipation of charges is based on induction.
In addition to these test-method standards there is a further standard, EN 1149-5:20085 which provides the performance requirements for anti-static PPE.
For the antistatic performance data relating to a particular product please refer to the relevant technical data.
ANNEXE 7: STATIC ELECTRICITY DISCHARGE
In order to avoid the creation of sparks (that might ignite an explosive atmosphere or cause operator discomfort), the garment and the wearer need to be properly grounded. This means that both the clothing and the wearer must be continuously earthed, taking care to ensure that the correct fabric side (inner or outer) is grounded in those cases where the garment s antistatic treatment is limited to one side. Special attention must also be paid to garments with attached socks or overshoes.
There are some essential rules for the safe discharge of static electricity:
9 Both wearer and garments must be correctly and continuously grounded via conductive safety shoes, ﬂ oor and/or grounding cable.
9 Electrostatic charges may build up on ancillary equipment. Breathing apparatus and other devices must therefore be separately grounded when being worn in conjunction with a garment.
SINGLE-SIDED VERSUS DOUBLE-SIDED
Some fabrics, particularly multi-layer, coated and coloured fabrics, may be antistatic treated on one side of the material only. An antistatic coating on both sides of a garment will reduce antistatic build-up and the attraction of particulates. However, neither single- or double-sided coatings will necessarily prevent the risk of ignition in highly explosive conditions such
as hydrogen atmospheres and oxygen-enriched air. In these cases the garment manufacturer must be consulted for guidance. In all situations the garment must be adequately grounded. With one-side treated garments care must be taken to ensure that it is the surface of the clothing which has been given antistatic treatment that is earthed.
ATEX DIRECTIVES For standard chemical protective clothing it is not a compulsory requirement for garments to be antistatically treated or have antistatic features. However due to the prevalence of operations and applications being managed under ATEX controls it is a much-requested feature.
Organizations in the EU must follow the ATEX1 Directives to protect employees from explosion risk in areas with an explosive atmosphere.
There are two ATEX directives:
9 The ATEX 95 equipment directive 94/9/EC2 is for equipment manufacturers and covers equipment and protective systems intended for use in potentially explosive atmosphere.3
9 The ATEX 137 workplace directive 99/92/EC4 provides minimum requirements for improving the safety and health protection of workers potentially at risk from explosive atmospheres.
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