An explosion is a sudden chemical reaction of a combustible substance with oxygen under release of high energy. These combustible substances can be gases, mists, vapours or dusts. An explosion can only proceed if three factors come together: a combustible substance (in appropriate distribution and concentration), oxygen (in the air) and an ignition source (e.g. electric spark).
It is important, therefore, to avoid an ignition or to minimise the effects of an explosion to a safe extent. For this, all operating equipment used in potentially explosive atmospheres must be designed, manufactured and marked according to the applicable regulations (ATEX product directive 2014/34/EU, IECEx regulations). The equipment is classified into groups and categories according to ATEX product directives or EPL according to IECEx standards in dependence on their area of use or the safety level of the protective measures and the frequency with which a potentially explosive atmosphere occurs. The highest possible potential hazard must be considered in this regard in each case.
Only explosion-proof equipment may be used in areas in which explosive atmospheres can occur in spite of all measures to avoid them. This equipment is constructed in various ignition protection classes in accordance with the corresponding construction regulations (IEC/EN 60079 standards series and ISO 80079-36/EN ISO 80079-36 standards series). Which ignition protection class the manufacturer uses depends on the type and function of the equipment. All standardised ignition protection classes in a category are equivalent. The manufacturer certifies in the EU declaration of conformity contained in the technical documentation that the product complies with the ATEX directives.