scope:

This part of IEC 60079 specifies the requirements, testing and marking of equipment emitting optical radiation intended for use in explosive atmospheres and also for equipment located outside the explosive atmosphere or protected by a Type of Protection listed in IEC 60079 -0, but which generates optical radiation that intentionally enters an explosive atmosphere. It covers the Groups I, II and II I, EPLs Ga, Gb, Gc, Da, Db, Dc, Ma and Mb. This standard 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 may 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. NOTE 1 See a) and d) of the introduction. This standard does not cover ignition by ultraviolet radiation and by absorption of the radiation n 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 Standard. This standard specifies requirements for equipment intended for use under atmospheric conditions. This standard supplements and modifies the general requirements of IEC 60079-0. Where a requirement of this standard conflicts with a requirement of IEC 60079-0, the requirement of this standard takes precedence. This standard applies to optical fibre equipment and optical equipment, including LED and aser equipment, with the exception of the equipment detailed below: 1. Non-array divergent LEDs used for example to show equipment status or backlight unction. 2. All luminaires (fixed, portable or transportable), hand lights and caplights (other than for Group I); intended to be supplied by mains (with or without galvanic isolation) or powered by batteries: - with continuous divergent light sources (for all EPLs), - with LED light sources (for EPL Gc or Dc only). 3. Optical radiation sources for Mb, Gb or Gc and Db or Dc applications which comply with Class 1 limits in accordance with IEC 60825-1. 4. Single or multiple optical fibre cables not part of optical fibre equipment if the cables : - - comply with the relevant industrial standards, along with additional protective means, e.g. robust cabling, conduit or raceway (for Gb, Db, Mb, Gc or Dc), - - comply with the relevant industrial standards (for Gc or Dc). closed equipment involving an enclosure that fully contains the optical 241 radiation and that complies with a suitable type of protection as required by the involved EPL, with the enclosure complying with one of the following conditions: - An enclosure for which an ignition due to optical radiation in combination with absorbers nside the enclosure would be acceptable (such as flameproof "d" enclosures), or - An enclosure for which protection regarding ingress of an explosive gas atmosphere is provided, such as pressurized "p" enclosures (IEC 60079-2), restricted breathing "nR" enclosure (IEC 60079-15), and dust protection "t" enclosures" (IEC 60079-31), or - An enclosure for which protection regarding ingress of absorbers is provided (such as IP 6X enclosures) and where no internal absorbers are to be expected. NOTE For these scope exclusions it is anticipated that the enclosures are not opened in the explosive atmosphere, so that ingress is protected.