Chapter 12 Ex Protection Concepts

← Back to document page

Session 12 Ex Protection ConceptsEx Protection ConceptsElectricalElectrical Symbol Typical IEC EPLTypical Zones IEC Standard Basic concept of protectionIncreased safety e Gb 1,2 IEC 60079 7 No arcs, sparks or hot surfaces. Enclosure IP54 or betterType n (non sparking) nA Gc2 IEC 60079 15Flameproofd Gb 1,2 IEC 60079 1 Contain the explosion , quench the flameType n (enclosed break) nC Gc2 IEC 60079 15Quartz/sand filled q Gb 1,2 IEC 60079 5Quench the flameIntrinsic safety ia Ga 0,1,2 IEC 60079 11Limit the energy of sparks and surface temperaturesIntrinsic safety ib Gb 1,2 IEC 60079 11Intrinsic safety ic Gc2 IEC 60079 11Type n (energy limitation)

Difference between Flameproof & Explosion proof boxes • Enclosure must have recessed screws or bolts for access • 1.5 safety factor vs. 4 times • Typically must be machined and fabricated at the factory vs. the field • Most Ex ‘d’ enclosures individually tested Flameproof vs. Explosion Proof

  Proof, Explosion, Boxes, Explosion proof, Explosion proof boxes