Also known as Explosion Proof, Explosion Protected, Ex Proof, Ex Rated – used worldwide as simple ways to say, “explosion resistance.” Sometimes you may also see ‘flame proof,’ though that term is a bit misleading. In practice, an Ex certification for a product means the equipment cannot be a source of ignition or, if it does explode, the explosion is confined and controlled within the equipment.
So, in the context of the traditional fire triangle, which illustrates the three required elements for fire, Ex equipment typically eliminates the ignition source:
Think of this like car engines: controlled explosions are used to drive pistons. In normal civilian cars, these are controlled within reasonable levels (for reliability and safety). In racing cars, engines are tuned for maximum power, so you may see flames shooting out of exhaust pipes, and sometimes race engines literally explode.
All Ex-certified equipment must come with certain documentation, including relevant certifications and test reports, and each piece of equipment must have its own Ex label. The exact markings on the label may very depending on local market requirements, but Ex labeling content is otherwise consistent. Labels indicate, for instance, temperature ratings, the exact explosion rating (group, type, division, class according to relevant standards and requirements), as well as what Notified Body did the certification.