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What are the requirements regarding the material of the equipment’s metal casing/metal components in explosion-proof certification? 2021-08-31 17:48 · Zhongnuo Testing specializes in explosion-proof certification. For electrical equipment of Category I, the total percentage by mass of materials used in the casing of such equipment, belonging to EPL Ma or Mb grades, should not exceed: a) 15% for aluminum, magnesium, titanium, and zirconium ； b) 7.5% magnesium, titanium, and zirconium. The above requirements do not apply to Class I portable measuring equipment; however, such equipment shall be marked with the symbol “X” in accordance with 29.2e, and special precautions during storage, transportation, and use shall be specified under the special conditions of use. Class I hand-held or bench-mounted electric drills (and their attached plug-in devices) incorporated in the housings of portable instruments and lighting fixtures can be made of lightweight alloys with a tensile strength of not less than 120 MPa, and such alloys must pass the friction spark test specified in GB/T 13813-2008. Materials for the enclosures of Class II electrical equipment, manufactured for different protection levels, shall not have a total content, on a mass percentage basis, exceeding: a) for EPL Ga: 10% of aluminum, magnesium, titanium, and zirconium ； 7.5% magnesium, titanium, and zirconium ； b) For EPL Gb: 7.5% magnesium and titanium ； c) For EPL Gc, no other requirements apply, except that the fan, fan cover, and ventilation grille baffles must meet the requirements of EPL Gb. If the above components are exceeded, the equipment shall be marked with an “X” in accordance with 29.2e, and the special conditions for safe use specified by Sinuo Testing shall contain sufficient information to enable the user to determine whether the equipment is suitable for use under specific conditions, such as to prevent the risk of ignition caused by impact or friction. For the manufacture of Class III electrical equipment, the total mass percentage of the materials used for the enclosures of such equipment at different protection levels shall not exceed: a) 7.5% for magnesium and titanium in the case of EPL Da ； b) For EPL Db: 7.5% magnesium and titanium ； c) For EPL Dc, apart from the fan, fan cover, and vent baffles which shall meet the requirements of EPL Db, there are no other requirements