Ex e – Increased safety
For electrical components that do not spark under normal working conditions but where
measures are applied to prevent high temperatures and the occurrence of arcs and sparks
Ex d – Flameproof enclosure
Parts, which can ignite a potentially explosive atmosphere, are surrounded by an enclosure, which are designed to withstand the pressure of an internal explosion and to prevent the propagation of the explosion to the atmosphere surrounding the enclosure.
Ex m – Encapsulation
Parts that could ignite a potentially explosive atmosphere by means of heat or sparks are
embedded in a sealing compound such that the potentially explosive atmosphere cannot be ignited. The compound is resistant to physical, electrical, thermal and chemical influences.
Ex p – Pressurized enclosure
The formation of a potentially explosive atmosphere inside an enclosure is prevented by
maintaining a positive internal pressure of protective gas in relation to the surrounding
atmosphere and, where necessary, by supplying the inside of the enclosure with a constant
flow of protective gas which dilutes any combustible mixtures.
Ex o – Oil immersion
Electrical equipment or parts of electrical equipment are immersed in a protective fluid (e.g. oil) in such a way that a potentially explosive atmosphere existing above the surface or outside of the encapsulation cannot be ignited.
Ex q – Powder filling
Filling the enclosure of electrical equipment with a fine grained packing material has the effect of making it impossible for an electric arc created in the enclosure under normal operating conditions to ignite a potentially explosive atmosphere surrounding the enclosure. Ignition must neither be caused by flames nor by elevated temperatures on the enclosure surface.
Ex i – Intrinsic safety
This protection providing measures to prevent the possibility of undue high temperatures
developing and the occurrence of sparks or arcs inside or on outer parts of electrical
equipment, which will not occur during regular operation, by an increased level of safety
Protection Ex n
This protection only applies to electrical equipment of the 3G category, the intent being that during regular operation and certain abnormal conditions, the potential of this equipment igniting a surrounding explosive atmosphere is eliminated. This type of protection aims at finding an economical compromise between the “normal” industrial standard and the high technical safety requirements of the types of protection for equipment of the 2G category.
Ex t – Protection by enclosure
The enclosure is enough seal so that no flammable dust can penetrate inside. The external
surface temperature of the housing is limited.
Zone Classification with the presence of DUST
Zone 21 An area in which an explosive atmosphere in the form of a cloud of combustible dust in air is likely to occur in normal operation of the plant.
Zone 22 An area in which an explosive atmosphere in the form of a cloud of combustible dust in air is not likely to occur in normal operation, if it does occur, will persist for a short period only.
Zone Classification with the presence of GAS
Zone 1 (Categorie 2), An area in which explosive gas is likely to be present during normal operation of the plant.
zone 2 (Categorie 3). An area in which explosive gas is not continuously present, but may exist for a short period of time.
For more information on the Ex regulations, please take a look at the links below.