Atex Brochure - Norgren - #6

06 I ATEX

While equipment for mining is identified as Group I, Group II is applicable for all remaining areas with potentially explosive atmospheres such as the chemical industry. Only Group II is subdivided into categories using the letters A, B and C, and only then for the pressurised encapsulation and intrinsically safe ignition protection categories in order to be able to classify the differences in the ignitability and the likelihood of flashover of potentially explosive mixtures. The most hazardous are defined in Group IIC; these therefore include IIB and IIA.

All devices are differentiated according to its maximum surface temperature that may occur. This must always be less than the ignition temperature of the flammable material.

Gases are divided into T-classes (see Table 3) and the permitted equipment is marked in the same way. Again a higher T-class fulfils the requirements of a lower class. Therefore, equipment with the identification EEx.JIC T6 covers all known gases.

For explosion prevention in dusty atmospheres, the maximum surface temperature is specified in °C.