REMINDER ON GROUPS OF DEVICES
Group I
Equipment of Group I is intended for use in mines susceptible to firedamp.
Equipment intended for mines where the atmosphere, in addition to firedamp,
may contain significant proportions of other flammable gases or combustible
dusts (i.e. other than methane or coal dust), shall be constructed and
tested in accordance with the requirements relating to Group I and also
to the subdivision of Group II and III corresponding to the other significant
flammable gases or combustible dusts. This equipment shall then be marked
appropriately.
Group II
Equipment of Group II is intended for use in places with an explosive gas
atmosphere other than mines susceptible to firedamp.
Equipment of Group II is subdivided according to the nature of the explosive
gas atmosphere for which it is intended. Group II subdivisions:
• IIA, a typical gas is propane;
• IIB, a typical gas is ethylene;
• IIC, a typical gas is hydrogen;
Group III
Equipment of Group III is intended for use in places with an explosive dust
atmosphere other than mines susceptible to firedamp.
Equipment of Group III is subdivided according to the nature of the explosive
dust atmosphere for which it is intended. Group III subdivisions:
• IIIA: suitable for combustible flyings;
• IIIB: suitable for combustible flyings and non-conductive dust;
• IIIC: suitable for combustible flyings, non-conductive dust and conductive
dust.
The ignition hazard assessment shall take into account the special
requirements for non-conductive dust due to electrostatic hazards generated
by insulated moving parts of non-electrical equipment.
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DOSATRON INTERNATIONAL S.A.S / 40