AS/NZS 60079.10.2, 2 nd – Explosive atmospheres, Part 10.2: Classification of areas – Explosive dust atmospheres

This part of IEC 60079 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
layers acting as one of the possible sources of release. In Clause 7 other general
considerations for dust layers are 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 might
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
(see Note 1).

NOTE 1 Atmospheric conditions include variations in pressure and temperature above and below reference levels
of 101,3 kPa (1 013 mbar) and 20 °C (293 K), provided that the variations have a negligible effect on the explosive
properties of the combustible materials.

It does not apply to

– underground mining areas,
– dusts of explosives that do not require atmospheric oxygen for combustion such as
pyrophoric substances, propellants, pyrotechnics, munitions, peroxides, oxidizers, waterreactive
elements or compounds, or other similar materials.
– catastrophic failures which are beyond the concept of abnormality dealt with in this
standard,
– any risk arising from an emission of toxic gas from the dust.

This standard does not apply to where a hazard might arise due to the presence of flammable
gas or vapour, but the principles may be used in the assessment of a hybrid mixture (see also
IEC 60079-10-1).

NOTE 2 Additional guidance on hybrid mixtures is provided in Annex C.
This standard does not take into account the effects of consequential damage following a fire
or an explosion