Electrical Apparatus for Use in Zone 20, Zone 21 and Zone 22 Hazardous (Classified) Locations - General Requirements
|Publication Date:||1 January 2006|
This standard specifies general requirements for the design, construction, testing and marking which is applicable to electrical apparatus protected by any recognized protection technique for use in areas where combustible dust may be present in quantities that could lead to a fire or explosion hazard.
This standard is supplemented or modified by the following standards concerning specific types of protection:
ANSI/ISA-61241-1 (12.10.03), Electrical Apparatus for Use in Zone 21 and Zone 22 Hazardous (Classified) Locations - Protection by Enclosures "tD"
ANSI/ISA-61241-2 (12.10.06), Electrical Apparatus for Use in Zone 21 and Zone 22 Hazardous (Classified) Locations - Protection by Pressurization "pD"
ANSI/ISA-61241-11 (12.10.04), Electrical Apparatus for Use in Zone 20, Zone 21, and Zone 22 Hazardous (Classified) Locations - Protection by Intrinsic Safety "iD"
ANSI/ISA-61241-18 (12.10.07), Electrical Apparatus for Use in Zone 20, Zone 21 and Zone 22 Hazardous (Classified) Locations - Protection by Encapsulation "mD"
The application of electrical apparatus in atmospheres which may contain explosive gas as well as combustible dust, whether simultaneously or separately, requires additional protective measures.
This standard does not specify requirements for safety, other than those directly related to the explosion risk.
Where the apparatus has to meet other environmental conditions, for example, protection against ingress of water and resistance to corrosion, additional methods of protection may be necessary. The method used is not to adversely affect the integrity of the enclosure.
This standard does not apply to dusts of explosives that do not require atmospheric oxygen for combustion, or to pyrophoric substances.
This standard is not applicable to electrical apparatus intended for use in underground parts of mines as well as those parts of surface installations of such mines endangered by firedamp and/or combustible dust.
This standard does not take account of any risk due to an emission of flammable or toxic gas from the dust.
Electrical apparatus and Ex components for use in explosive dust atmospheres shall also comply with the applicable requirements for similar apparatus for use in unclassified locations.
NOTE Requirements for safety of electrical equipment in ordinary (unclassified) locations can be found in ANSI Standards, NEMA Standards, Federal Regulations, etc. Apparatus listed by a Nationally Recognized Testing Laboratory is considered to meet the applicable requirements found in these standards. A list of commonly appli ed standards is shown in informative Annex A.