IEC 60079-28-ed.3.0

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Bezeichnung: IEC 60079-28-ed.3.0

Ausgabedatum: 21.11.2025

Seiten: 32

Land: Internationale technische Norm

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IEC 60079-28:2025 specifies additional requirements for Ex Equipment, Ex associated equipment or Ex Components containing optical systems emitting optical radiation, which is exposed to explosive atmospheres. These additional requirements are applicable for all equipment groups and all Equipment Protection Levels (EPL). This document contains requirements for optical radiation in the wavelength range from 380 nm to 10 µm. It covers the following ignition mechanisms: • Optical radiation is absorbed by surfaces or particles, causing them to heat up, and under certain circumstances this might allow them to attain a temperature which will ignite a surrounding explosive atmosphere. • In rare special cases, direct laser induced breakdown of the gas at the focus of a strong beam, producing plasma and a shock wave both eventually acting as ignition source. These processes can be supported by a solid material close to the breakdown point. • Annex A provides guidance when considering ignition mechanisms that influence the hazard of optics in explosive atmospheres. This document applies to a) laser equipment; and b) optical fibre equipment; and c) any optical system that converts light into convergent beams with focal points within the hazardous area only. This document does not apply to: d) laser equipment for EPL Mb, Gb, Gc, Db or Dc applications which complies with Class 1 limits in accordance with IEC 60825-1; or e) Single or multiple optical fibre cables not part of optical fibre equipment if the cables: 1) comply with the relevant industrial standards for optical fibre cables, along with additional protective means, for example robust cabling, conduit or raceway (for EPL Gb, Db, Mb, Gc or Dc); or 2) comply with the relevant industrial standards for optical fibre cables (for EPL Gc or Dc); or f) Optical radiation sources as defined in i) to iii) above where the optical radiation is fully contained in an enclosure complying with one of the following Types of Protection suitable for the EPL, or the minimum ingress protection rating specified: 1) flameproof "d" enclosures (IEC 60079-1); or 2) pressurized "p" enclosures (IEC 60079-2); or 3) restricted breathing "nR" enclosure (IEC 60079-15); or 4) dust protection "t" enclosures" (IEC 60079-31); or 5) an enclosure that provides a minimum ingress protection of IP 6X and where no internal absorbers are to be expected and complying with "Tests of enclosures" in IEC 60079-0. This document does not cover ignition by ultraviolet radiation and by absorption of the radiation in the explosive mixture itself. Explosive absorbers or absorbers that contain their own oxidizer as well as catalytic absorbers are also outside the scope of this document. This document supplements and modifies the general requirements of IEC 60079-0. Where a requirement of this document conflicts with a requirement of IEC 60079-0, the requirement of this document takes precedence. This third edition cancels and replaces the second edition published in 2015. This edition constitutes a technical revision IEC 60079-28:2025 specifie les exigences supplementaires applicables aux appareils Ex, aux appareils associes Ex ou aux composants Ex contenant des systemes optiques emettant un rayonnement optique, qui sont exposes a des atmospheres explosives. Ces exigences supplementaires sappliquent a tous les groupes dappareils et a tous les niveaux de protection du materiel (EPL, Equipment Protection Levels). Le present document contient les exigences relatives aux rayonnements optiques dans la plage de longueurs donde comprise entre 380 nm et 10 µm. Il couvre les mecanismes dallumage suivants: – le rayonnement optique est absorbe par les surfaces ou particules, provoquant leur echauffement et, dans certaines circonstances, celles-ci peuvent atteindre une temperature qui amorce linflammation de latmosphere explosive environnante; – dans certains cas rares particuliers, le craquage direct dun gaz par laser, au point de focalisation dun faisceau puissant, produisant un plasma et une onde de choc, les deux agissant en definitive comme source dinflammation. Ces processus peuvent prendre naissance dans un materiau solide proche de son point de craquage; – Annexe A fournit des recommandations lors de lexamen des mecanismes dinflammation qui influencent le danger optique dans les atmospheres explosives. Le present document sapplique: a) aux equipements laser; et b) aux equipements a fibres optiques; et c) a tout systeme optique qui convertit la lumiere en faisceaux convergents avec des points focaux situes dans la zone dangereuse uniquement. Le present document ne sapplique pas: d) aux equipements laser pour les applications EPL Mb, Gb, Gc, Db ou Dc qui satisfont aux limites de Classe 1 conformement a lIEC 60825-1; e) aux cables a fibres optiques simples ou multiples ne faisant pas partie des equipements a fibres optiques si les cables: 1) satisfont aux normes industrielles pertinentes pour les cables a fibres optiques, ainsi que les moyens de protection supplementaires, comme les cablages robustes, les conduits ou les chemins (pour EPL Gb, Db, Mb, Gc ou Dc); ou 2) satisfont aux normes industrielles pertinentes pour les cable a fibres optiques (pour EPL Gc ou Dc); ou f) aux sources de rayonnement optique telles que definies aux points a) a c) ci-dessus, lorsque le rayonnement optique est totalement contenu dans une enveloppe satisfaisant a lun des modes de protection suivants adaptes a lEPL, ou a la caracteristique assignee minimale de protection contre les penetrations specifiee: 1) les enveloppes "d" antideflagrantes (IEC 60079-1); ou 2) des enveloppes "p" sous pression (IEC 60079-2); ou 3) une enveloppe "nR" a respiration limitee (IEC 60079-15); ou 4) les enveloppes "t" de protection contre la poussiere (IEC 60079-31); ou 5) une enveloppe qui fournit une protection minimale contre la penetration IP 6X et lorsquaucun absorbeur interne nest attendu, et qui satisfait aux "Essais des e