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Technical Specifications

What Is The Difference Between Flameproof And Increased Safety Explosion-Proof Boxes

Explosion-Proof Types:

The explosion-proof methods of increased safety (Ex e) and flameproof (Ex d) enclosures differ significantly.

flameproof box

Flameproof Type:

The flameproof method involves enclosing parts that might produce arcs or sparks during normal operation within a robust enclosure. This enclosure withstands explosion pressures without damage, ensuring that flames and dangerous high temperatures generated by an explosion inside do not transfer outside. It ensures that these are extinguished and cooled upon passing through the flameproof joint, preventing ignition of explosive gases outside the enclosure.

Increased Safety Type:

In increased safety (Ex e) enclosures, there is no production of sparking or dangerous high temperatures during normal operation. Additional measures are taken to enhance safety and reliability.


Why are there so many screws in flameproof enclosures, but not in increased safety types?

Flameproof enclosures require a high level of precision in their gap tolerances to prevent internal explosions from igniting external explosive gases. More screws ensure tighter seams and greater safety. This is why flameproof enclosures have numerous screws.

Increased safety focuses on the protective level. Sealing effectively with just four screws is sufficient.


Flameproof enclosures are not restrictive about the internal components since they can withstand any arcs or sparks inside. As long as the outer shell can withstand the explosion pressure without damage, it ensures that flames and high temperatures generated inside are extinguished and cooled when passing through the flameproof joint, preventing external ignition.

Increased safety enclosures must first ensure that internal devices do not produce sparks, dangerous high temperatures, or arcs. Further protective measures are then taken to enhance safety and reliability.


For instance, a circuit breaker designed for a flameproof enclosure cannot be used in an increased safety enclosure. However, converting an increased safety enclosure to a flameproof one is permissible.

Therefore, the appropriate type of explosion-proof enclosure should be selected based on actual requirements, and substitutions should not be made casually.



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