The basics of dust-explosion protection - STAHL - #11

After this, in Germany a certificate of conformity for electrical equipment to be used in Zone 10 became a legal requirement, based or the VDE standard. VDE 0170/0171, Part 13 developed by following the action of IEC. Based on this standard BUS (German Test! a bora to ry and Certification Body} ant! row EXAP-/ leva beer' certrying electronic devices for use in Zone 10 since 1980, in co-operation with legal authorities and the PTB.

Directive 94/9/EC provided a new regulation for explosion protection in Europe. This directive formulates the requirements to be fulfilled by manufacturers of electrical and no electrical equipment. The Explosion Protection Regulation of December 1996 (Explosionsschutzverordnung] transfers this directive into German law. In Annex I, Directive 94/9/EC mentions, in the course of an explanation of Equipment Group2, only the danger uresantei: by «ri enplos vu ttinosuhere consisting of a dust/air mixture, which does not seem to in-ckie'o rlnst deposits "ho spot: ,-i ■ isk presented by these dust deposits as a source of release is only taken into account in the zone classification insofar as other circumstances, such as a swirling up ot the dust by air currents, could C3use an explosive atmosphere.

The questions of proper use are addressed by Directive 1999/92/EC. The current treatment of dust explosion protection in Directive 1999/92/EC is not very comprehensive and is limited to a simple definition of zones and a reference to deposits of combustible dust.

CENELEC, the European Committee for Electro-technical Standardization, has developed Standards EN 50281-1-1 and EN 50281-1-2 in parrallel with IEC 61241 and based on it. These standards make use of the 3-zone concept as set out in European Directives 94/9/EC and

99/92/EC. As part of the consolidation of standards dealing with dust and gas, the goal at the IEC level is to adapt the numbering of the dust standards to the IEC 60079 standard series (Table 5). This plan is laudable, because it would create analogous standards for gas and dust explosion protection.