Answer Posted / aris
There is a lot of confusion when it comes to “flameproof” products. Ex d or “Flameproof” means that an enclosure or junction box is constructed and certified as Explosion Protected according to the “Flameproof” standard. The “Flameproof” philosophy is that should an explosion occur within the enclosure, it will either be contained or the escaping flame will be cooled by a “flame-path” thus mitigating the risk of igniting an explosive outside atmosphere. Other equipment designated flameproof, like a flameproof cable gland, is constructed in such a way that it will maintain the flameproof integrity of a flameproof enclosure to which it is fitted. Ex e, on the other hand, means that the enclosure is constructed and certified as “Explosion Protected” according to the “Increased Safety” standard. The philosophy with Ex e is to provide an impact resistant enclosure and also to ensure that its contents are certified such that they will never produce sparks or temperatures or current creepage that could ignite the flammable atmosphere which may enter the enclosure. Ex e rated enclosures are therefore explosion protected but are not “Flameproof”. In selecting both Ex d or Ex e equipment it is necessary to ensure the Temperature “T”-rating and the gas group certification is appropriate for the specific prevailing flammable atmosphere. Both Ex e and Ex d junction boxes can be used on Zone 1 areas. Ex d Flameproof boxes are normally manufactured from heavy patterned cast iron and are generally also suitable for use underground in coal mines. Ex e Increased Safety boxes are normally manufactured from an engineered plastic and are generally suitable for surface applications and in non-fiery mines. Ex e is usually a less expensive method of protection than Ex d. We are always here to help or give advice if you are not sure
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