UL Standard for Safety Explosive atmospheres – Part 0: Equipment – General requirements
|Publication Date:||21 October 2009|
This part of IEC 60079 specifies the general requirements for construction, testing and marking of electrical equipment and Ex components intended for use in explosive atmospheres.
1DV.1 DR Modification of Clause 1 first paragraph to replace with the following:
1DV.1.1 This standard specifies the general requirements for construction, testing and marking of electrical equipment and Ex components to use in explosive atmospheres. Explosive atmospheres are identified by the National Electrical Code®, NFPA 70 as hazardous (classified) locations and include the following specified locations.
• Class I, Zone 0;
• Class I, Zone 1;
• Class I, Zone 2;
• Zone 20;
• Zone 21; and
• Zone 22.
Unless modified by one of the parts in the IEC 60079 series, electrical apparatus complying with this standard is intended for use in hazardous areas in which explosive gas atmospheres, caused by mixtures of air and gases, vapours or mists, exist under normal atmospheric conditions of
• temperature -20 °C to +60 °C;
• pressure 80 kPa (0,8 bar) to 110 kPa (1,1 bar); and
• air with normal oxygen content, typically 21 % v/v.
The application of electrical apparatus in atmospheric conditions outside this range may need special consideration.
NOTE 1 Although the normal atmospheric conditions above give a temperature range for the atmosphere of -20°C to +60°C, the normal ambient temperature range for the equipment is -20°C to +40°C, unless otherwise specified and marked. See 5.1.1.
NOTE 2 In designing equipment for operation in explosive atmospheres under conditions other than the atmospheric conditions given above, this standard may be used for guidance. However, additional testing related specifically to the intended conditions of use is recommended. This is particularly important when the types of protection 'flameproof enclosure "d"' (IEC 60079-1) and 'intrinsic safety "i"' (IEC 60079-11 or IEC 61241-11) are applied.
1DV.2 DR Modification of Clause 1 Note 2 as follows:
1DV.2.1 Delete "(IEC 60079-1) " and "(IEC 60079-11 or IEC 61241-11)".
NOTE 3 Requirements given in this standard result from an ignition hazard assessment made on electrical equipment. The ignition sources taken into account are those found associated with this type of equipment, such as hot surfaces, mechanically generated sparks, thermite reactions, electrical arcing and static electric discharge in normal industrial environments.
NOTE 4 It is acknowledged that, with developments in technology, it may be possible to achieve the objectives of the IEC 60079 series of standards in respect of explosion prevention by methods that are not yet fully defined. Where a manufacturer wishes to take advantage of such developments, this International Standard, as well as other standards in the IEC 60079 series, may be applied in part. It is intended that the manufacturer prepare documentation that clearly defines how the IEC 60079 series of standards has been applied, together with a full explanation of the additional techniques employed. The designation "Ex s" has been reserved to indicate a type of protection that is not defined by the IEC 60079 series of standards, but may be referenced in national requirements.
1DV.3 DR Delete Clause 1 Note 4.
1DV.3.1 This Note does not apply.
NOTE 5 Where an explosive gas atmosphere and a combustible dust atmosphere are, or may be, present at the same time, the simultaneous presence of both should be considered and may require additional protective measures.
This standard does not specify requirements for safety, other than those directly related to the explosion risk. Ignition sources like adiabatic compression, shock waves, exothermic chemical reaction, self ignition of dust, naked flames and hot gases/liquids, are not addressed by this standard.
NOTE 6 Such equipment should be subjected to a hazard analysis that identifies and lists all of the potential sources of ignition by the electrical equipment and the measures to be applied to prevent them becoming effective.