In the design and use of electrical devices we must manage conductive parts with different electrical potential, with even very high voltage differences. The risk of formation of electric arcs in the air and creeping currents on the surface of the insulation material must be considered. To limit these phenomena, during the design phase we intervene on the distances between exposed conductive parts.

In a world where the installation speed, the overall site security and the installation and maintenance costs are increasingly important, the use of specific connectors as FlowEx series can find wide application.

Among the equipment suitable for use in explosive atmospheres with an EPL Gb, those with increased safety are undoubtedly the most similar to an industrial standard product. Over the years this method of protection has spread in junction boxes and in particular in lighting. In general, the lighter and more portable constructions of the increased safety products have been appreciated by plant engineers.

Often the meaning of the supplementary letter is little known, misunderstood and misinterpreted. Not understanding the difference between component and equipment or thinking that a certificate with the final "X" is a sort of B-series certificate with strong limitations on the use of the equipment is completely anachronistic today.

The systems are mainly divided into systems with metal protective conduits and cable systems. The various devices require cable entries suitable for the type of protection used. The type of cable entry may appear to be a mere theoretical argument, but it has a decisive impact on the safety level of the system.

In sites where there is a risk of the formation of an explosive atmosphere, we often find the electrical conduit in a metal protective tube (also called conduit conduit). Although it has recently been joined by more versatile armored and non-armored cable systems, with cable gland entry, its use is recommended in plants where production or use and maintenance activities can present dangerous situations for the integrity of the cables.

Sealing fittings are often considered only as secondary or minor components, but the safety of an installation with metal electrical conduits and related explosion-proof enclosures depends on them. The main function of a conduit sealing fitting is to prevent the propagation of an explosion from the inside of the ‘Ex d’ flameproof enclosure to the outside.

Explosion-proof joints are one of the basic aspects of the protection offered by an equipment or an explosion-proof enclosure. For this reason, understanding their function is a prerequisite for the correct use and the proper maintenance of all electrical devices that adopt this type of protection.

A fundamental principle of the ATEX Directive 2014/34 / EU, shared with the other Union directives, is the limitation of legislative harmonization to essential health and safety requirements of public interest. Within this legislative harmonization, a role of primary importance is played by the harmonized technical legislation and the concept of the state of the art. The ATEX Directive refers to this concept as a requirement requested of manufacturers.

Each equipment that must be installed in an ATEX classified area must have a certain level of protection, indicated in the legislation with the acronym EPL (Equipment protection Level). The level of protection is obtained by applying technical regulations that define the protection methods. There are many ways of protection, some have a historical origin, others are more recent...

1. Preface Dust explosions can occur in any activity in which solid materials are treated and finely divided (metals, organic substances,...