UL 60079-28:2017 Explosive Atmospheres一Part 28: Protection of Equipment and Transmission Systems Using Optical Radiation.
1 DV.1 DR Modification of Clause 1 to replace with the following:
1DV.1.1 DR This part of IEC 60079 standard specifies the requirements, testing and marking of equipment emitting optical radiation intended for use in explosive atmospheres. It also covers equipment located outside the explosive atmosphere or protected by a Type of Protection listed in IEC UL 60079-0, but which generates optical radiation that is intended to enter an explosive atmosphere. It covers Groups I, II and Ill, and EPLs Ga, Gb, Gc, Da, Db, Dc, Ma and Mb.
1.2 This standard contains requirements for optical radiation In the wavelength range from
380 nm to 10 pm. 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.
1.3 This standard 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 standard.
1.4 This standard specifies requirements for equipment intended for use under atmospheric conditions.
IDV.1.5 DR Annex F outlines the application of this standard for equipment and transmission systems using optical radiation in areas classified using the Division method.
1DV.1.6 DR This standard supplements and modifies the general requirements of IEC jjj,
60079-0. Where a requirement of this standard conflicts with a requirement of lEG j,
60079-0, the requirement of this standard takes precedence.
1DV.1.7 DR Where references are made to other IEC 60079 standards. the referenced requirements found in these standards apply as modified by any applicable U.S. National Differences.UL 60079-28 pdf download.