EMMUA 214 States
2.1 Equipment Groups
Page 7.
Group I equipment is designated for use below ground and associated areas where methane (firedamp) is the flammable gas.
Group Il equipment is used primarily above ground where any other flammable gas may be present.
Group Il equipment may be further divided into sub groups, e.g. IIC, in order to define the gas subdivisions with which it may be used.
Group Ill equipment is used where flammable dust may be present. Group lil equipment may be further divided into sub groups, e.g. IllC, jn order to define the fibre/non-combustible dust/combustible dust subdivisions with which it may be used.
ATEX does not recognise Group Ill. The relationship between ATEX and IEC equipment groups is given in Table 5.
So that we can understand the protection concepts underpinning hazardous area equipment we must first understand the basic principles of flammable materials.
Above ground, offshore, at sea, the production of oil-based and chemical materials in the oil and petrochemical industries increases the risk of hazardous atmospheres. A key factor to consider is that equipment could be a source of ignition when product vapours and dust leakages are allowed into the local atmosphere.