Abstract
Electrical and non-electrical equipment used in hazardous areas can be designed in the type of protection “flameproof enclosure”. Following this safety concept, potential ignition sources are enclosed by containments. If a combustible enters the enclosure and is ignited, flame transmission to the surrounding explosive atmosphere has to be definitely avoided. Additionally, the enclosure must be robust enough to withstand the emerging explosion pressure without rupturing or temporarily opening up any of the joints to a critical value. The design of these enclosures is, therefore, related to the maximum explosion pressure of an internal explosion and as a consequence, the enclosures must be constructed with an enormous material effort. To develop more efficient enclosure constructions, it is necessary to reduce the maximum explosion pressure.
This paper presents a novel approach to reducing the explosion pressure within flameproof enclosures, which offers the possibility of improving the design of flameproof enclosures, leading to lower production costs without reducing any safety aspects. This approach is based on the integration of porous structures into the enclosure walls acting as venting and flame quenching elements. Different porous structures were investigated in terms of their ability to relieve pressure and to avoid flame transmissions. It is shown that proper use of these structures can enormously decrease the maximum explosion pressure inside the enclosure while safely avoiding flame transmissions, depending on the structure specifics. Based on these results it is possible to introduce a novel approach of flameless venting, which is named, regarding its application in flameproof enclosures, “flameproof explosion pressure relief”.
