Ex设备，即指防爆电气设备，是指使用在危险场所的电气设备。而所谓危险场所，是指空气中因含有一定量的易燃性的气体（蒸汽、液体、粉尘）而有可能引起着火和爆炸危险的场所。

对于危险场所的定义可参考IECEx的官方解释：

What is an Ex area?

Ex areas can be known by different names such as “Hazardous Locations”, “Hazardous Areas” “Explosive Atmospheres”, and the like and relate to areas where flammable liquids, vapours, gases or combustible dusts are likely to occur in quantities sufficient to cause a fire or explosion.

The modern day automation of industry has meant an increased need to use equipment in Ex areas. Such equipment is termed “Ex equipment”

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