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23
2026
-
02
Core Explosion-Proof Type and Principle
The most widely used type; the enclosure is made of high-strength cast iron, die-cast aluminum, or welded steel plate, providing explosion resistance (withstanding internal explosion pressure without rupture) and non-transmission of explosion (achieved through precise flameproof gaps and sufficiently long flame paths that cool the flame below its ignition temperature); suitable for Zone 1 and Zone 2; commonly found in underground coal mines and in pump and fan drives at oil refineries.
Flameproof type (Ex d/db)
The most widely used type: the enclosure is made of high-strength cast iron, cast aluminum, or welded steel plate, offering explosion resistance (withstanding internal explosion pressure without rupture) and non-transmission of explosion (achieved through precise flameproof gaps and sufficiently long flame paths that cool the flame below its ignition temperature); suitable for Zone 1 and Zone 2; commonly employed in underground coal mines and for pump and fan drives in oil refineries.
Increased safety type (Ex e/eb/ec)
Without an explosion-proof enclosure, comprehensive safety enhancements—such as higher insulation classes, increased electrical clearances and creepage distances, limits on winding temperature rise, and VPI vacuum impregnation—are employed to ensure that no hazardous ignition sources are generated under normal operating conditions or permissible overloads. The design is lightweight and cost-effective, making it well suited for Zone 2 applications; however, it places high demands on maintenance.
Positive-pressure type (Ex p)
Clean air or nitrogen is continuously purged into the enclosure to maintain a slight positive pressure, thereby preventing the ingress of flammable media; a dedicated pressure monitoring and make-up gas system is required; this solution is suitable for large-scale, high-temperature equipment or IIC-class hazardous gas environments.
Non-sparking type (Ex n), dust-protected type (Ex tD)
Non-sparking types limit mechanical and electrical sparks and are suitable for Zone 2; dust explosion protection, on the other hand, is designed to address combustible dust clouds or layers, with stringent enclosure sealing and surface-temperature control, and is used in applications such as grain processing, metal polishing, and mining.
Related Information
2026-02-23
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