This standard is concerned with the identification and classification of areas where explosive dust atmospheres and combustible dust layers are present@ in order to permit the proper assessment of ignition sources in such areas. In this standard@ explosive dust atmospheres and combustible dust layers are treated separately. In Clause 4@ area classification for explosive dusts clouds is described@ with dust l ayers acting as one of the possible sources of release. In Clause 7@ the hazard of dust layer ignition is described. The examples in this standard are based on a system of effective housekeeping being implemented in the plant to prevent dust layers from accumulating. Where effective housekeeping is not present@ the area classification includes the possible formation of explosive dust clouds from dust layers. The principles of this standard can also be followed when combustible fibres or flyings may cause a hazard. This standard is intended to be applied where there can be a risk due to the presence of explosive dust atmospheres or combustible dust layers under normal atmospheric conditions. It does not apply to ?C underground mining areas@ ?C areas where a risk can arise due to the presence of hybrid mixtures@ ?C dusts of explosives@ pyrophoric or pyrotechnic substances@ or other dusts that do not require atmospheric oxygen for combustion@ ?C catastrophic failures which are beyond the concept of abnormality dealt with in this standard (see Note 1)@ ?C any risk arising from an emission of flammable or toxic gas from the dust. This standard does not take into account the effects of consequential damage following a fire or an explosion. NOTE 1 Catastrophic failure in this context is applied@ for example@ to the rupture of a storage silo or a pneumatic conveyor. NOTE 2 In any process plant@ irrespective of size@ there can be numerous sources of ignition apart fr om those associated with equipment. Appropriate precautions will be necessary to ensure safety in this context@ but these are outside the scope of this standard.
ISA 60079-10-2-2013 history
2013ISA 60079-10-2-2013 Explosive Atmospheres – Part 10-2: Classification of areas - Combustible dust atmospheres (12.10.05)