"UL Standard for Safety Electrical Apparatus for Explosive Gas Atmospheres – Part 18: Construction@ Test and Marking of Type of Protection Encapsulation ""m"" Electrical Apparatus (COMMENTS DUE: NOVEMBER 23@ 2015)"
"This standard gives the specific requirements for the construction@ testing and marking of electrical equipment@ parts of electrical equipment and Ex components with the type of protection encapsulation ""m"" intended for use in explosive gas atmospheres or explosive dust atmospheres. This standard applies only for encapsulated electrical equipment@ encapsulated parts of electrical equipment and encapsulated Ex components (hereinafter always referred to as ""m"" equipment) where the rated voltage does not exceed 11 kV. The application of electrical equipment in atmospheres@ which may contain explosive gas as well as combustible dust simultaneously@ may require additional protective measures. This standard does not apply to dusts of explosives@ which do not require atmospheric oxygen for combustion@ or to pyrophoric substances. This standard does not take account of any risk due to an emission of flammable or toxic gas from the dust. 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. Where references are made to other IEC 60079 standards@ the referenced requirements found in these standards shall apply as modified by any applicable U.S. National Differences."