walsall Explosion Protected Electrical Equipment

A Guide to the Selection of Electrical Equipment for Installation inHazardous AreasA Guide to the Selection of Electrical Equipment for Installation inHazardous AreasIgnition TemperatureTable 5Temperature ClassesIngress ProtectionTable 8IP Rating IPXYThe ignition temperature is the lowest temperature on the surface at whichan explosive atmosphere will ignite.Gases and dusts have been divided into temperature classes according totheir ignition temperatures so that electrical equipment can be furthersub-divided into six temperature classes T1 to T6.The temperature classes are shown in Table 5.Note. The maximum operating surface temperature of a piece ofelectrical equipment must always be below the ignition temperatureof the explosive mixture, see Table 6 opposite.Temperature Maximum SurfaceClassTemperature ˚CT1 450T2 300T3 200T4 135T5 100T6 85Table 6Self ignition Temperatures and TemperatureClassesBecause hazardous area electrical equipment is very often used inhostile atmospheric environments the standards call for minimumlevels of protection against water and dust. For example the minimumlevel set is IP54 however in the case of dust hazards the minimum levelingress protection is set at IP64.The range of IP levels are shown in Table 8 oppositeX Protected From Y Protected From0 None 0 None1 Solids