Why can flameproof enclosures and flameproof joints provide explosion protection?

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The flameproof type is a relatively common form of #explosion-proof# protection, and currently, most explosion-proof products on the market are of this type as well. What is flameproofing? Flame isolation means that when an explosion occurs inside the enclosure of an electrical device, the flames are ejected through the various joints, preventing the explosive mixture outside the enclosure from exploding. Electrical equipment with an explosion-proof enclosure is called an explosion-proof electrical device. An electrical equipment enclosure capable of withstanding the explosive pressure generated by an internal mixture of explosive gases, while preventing the spread of such explosions to the explosive mixtures surrounding the enclosure, is known as a flameproof enclosure. In simple terms, it can both resist explosions and prevent them from propagating. https://pic2.zhimg.com/80/v2-324b50c7fe434140452a9fc677d40305_720w.jpg What is the reason why flameproof enclosures can serve as flame barriers? When an explosion occurs inside the enclosure of an electrical device, the flames are discharged through various joints. When the gaps, length, and surface roughness of the joint surfaces meet the specified requirements, these gaps can serve to extinguish the flame. They also act as a cooling mechanism, allowing the flame passing through them to be sufficiently cooled, thereby reducing its temperature below the minimum level required to ignite the explosive mixture outside the enclosure. As a result, no explosion will occur, and these gaps thus provide explosion isolation. Why can the gap in the flameproof joint serve as a flameproof barrier? Put simply, it is the flameproof enclosure that covers the flame; thus, if an explosion occurs inside the enclosure, it cannot spread to the outside. Scientifically speaking, it is the gap in the flameproof joint that disrupts the flame reaction zone necessary for the combustion and explosion of flammable mixtures; moreover, the flame loses heat as it propagates through this gap. As a result, after passing through the gap in the flameproof joint, the flame becomes smaller and weaker, and its temperature drops, preventing it from igniting the explosive mixtures outside the flameproof enclosure. To ensure explosion-proof performance, GB3836.2-2010 “Explosive atmospheres – Part 2: Flameproof enclosures ‘d’” specifies the maximum gap or diameter difference ic at flameproof joints, the minimum effective length L of such joints, the minimum effective distance from the edge of a flameproof joint to the edge of a screw hole, as well as the surface finish requirements for these joints. https://pic4.zhimg.com/80/v2-26f80b3b93fd1f042c611aa296a02d53_720w.jpg https://pic2.zhimg.com/80/v2-9744f7beabb5cdfda7ee00de2e537521_720w.jpg For more information on explosion protection, please follow us. Thank you!