scope:

This standard is concerned with the classification of areas where explosive dust/air mixtures and combustible dust layers are present, in order to permit the proper selection of equipment for use 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 layers acting as one of the possible sources of release. In Clause 7 the hazard of dust layer ignition is describes. The standard assumes effective housekeeping based on a system cleaning for the plant. The principles of the standard can also be followed when combustible fibres or flying may cause a hazard. This standard is intended to be applied where there can ce a risk due to the presence of explosive dust/air mixtures or combustible dust layers under normal atmospheric conditions. It does not apply to: - underground mining areas, - areas where a risk can arise due to the presence of hybrid mixtures, - dusts of explosives which do not require atmospheric oxygen for combustion, or to pyrophoric substances, - catastrophic failures, which are beyonf the concept of abnormality dealt with in this standard (see note 1), - any risk arising from an emission of flammable or toxic gas from the dust. This standard does not take into account the effect of consequential damage following a fire or an explosion.