The italian approach to the classification of areas where combustible dusts may be present

The classification of areas in presence of combustible dusts is generally more complex than in presence of vapours and/or gases. This is due to the greater number of parameters to be taken into account (e.g. the particle-size and the humidity), to the difficulty of using an all-purpose approach and to the layer hazard. As a result, the International Standards on the subject are often quite generic, for example when they set the radius of the hazardous zones as a constant quantity independent of the characteristics of the examined system. The CEI (Italian Electrotechnical Committee) is going to issue a guide aiming at, among other aspects, establishing safety measures more suitable to different situations. This paper briefly outlines the area classification procedure, describes the approaches respectively adopted by the international and the Italian national guide and highlights the innovations that will be introduced by the latter. Finally, the results of a simple case study are presented: they have been obtained by using "ProgEx Dust", a software issued by the CEI, in order to help technicians in their work