爆炸性环境 - 第28部分：使用光辐射的设备和传输系统的保护

[中文适用范围]： IEC 60079-28:2025 规定了适用于含有光学系统并发射光学辐射的Ex设备、Ex关联设备或Ex组件的附加要求，这些设备可能暴露在爆炸性气体环境中。这些附加要求适用于所有设备组别和所有设备保护等级（EPL）。本文件涵盖了波长范围从380 nm到10 µm的光学辐射要求。它包括以下点火机制： • 光学辐射被表面或粒子吸收，使它们升温，在特定条件下可能会达到足以点燃周围爆炸性气体环境的温度。 • 在极少数特殊情况下，强光束焦点处的气体可能因激光直接诱导击穿而产生等离子体和冲击波，最终成为点火源。在这些过程中，靠近击穿点的固体材料可能起到支持作用。 • 附录A提供了在考虑影响爆炸性气体环境中光学部件危险的点火机制时的指导。 本文件适用于以下设备： a) 激光设备； b) 光纤设备； c) 仅在危险区域内形成聚焦点的光学系统，即能够将光转化为汇聚光束的光学系统。 本文件不适用于以下情况： d) 符合IEC 60825-1中规定的1类限值的EPL Mb、Gb、Gc、Db或Dc应用的激光设备； e) 若光纤电缆： 1) 符合光纤电缆的相关工业标准，并配备额外的保护措施（如坚固的布线、导管或线槽）（适用于EPL Gb、Db、Mb、Gc或Dc）；或 2) 符合光纤电缆的相关工业标准（适用于EPL Gc或Dc）； f) 如上i)至iii)所定义的光学辐射源，其中光学辐射完全包含在符合以下保护类型之一的外壳中，或满足规定的最低防尘等级： 1) 防爆“d”外壳（IEC 60079-1）； 2) 增压“p”外壳（IEC 60079-2）； 3) 限制呼吸“nR”外壳（IEC 60079-15）； 4) 防尘“t”外壳（IEC 60079-31）； 5) 提供至少IP 6X防尘等级的外壳，且外壳内不预期存在吸收器，并符合IEC 60079-0中“外壳测试”的规定。 本文件不涵盖由紫外辐射或爆炸混合物自身吸收辐射引起的点火。爆炸吸收器、含有自身氧化剂的吸收器以及催化吸收器均不在本文件的范围之内。 本文件对IEC 60079-0的一般要求进行了补充和修改。当本文件的要求与IEC 60079-0的要求发生冲突时，应以本文件的要求为准。 本版为第三版，取代2015年发布的第二版，为技术修订版。 [外文原描述]： 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