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Performance Characteristics

What Is The Difference Between Flameproof And Positive Pressure Types Of Explosion-Proof Enclosures

Explosion-proof enclosures, especially prevalent in distribution applications, come in various comprehensive types. Among them, flameproof and positive pressure explosion-proof enclosures are the most common, meeting a wide range of requirements. Many users often wonder about the differences between these two types. Let’s delve into their distinct features.

flameproof distribution box-7

Explosion Protection Principles:

Flameproof Explosion-Proof Enclosure:

True to its name, this type isolates explosive events. It houses electrical components that might generate sparks, arcs, or high temperatures, effectively separating the device’s internal space from the external environment. The enclosure is robust enough to withstand internal explosions and the resulting pressures without damage. Furthermore, the gaps in its structure serve to cool any flames, slowing down their spread or halting the acceleration process, thus preventing external explosive engagement.

Positive Pressure Explosion-Proof Enclosure:

This type works by injecting fresh air or inert gas at a certain pressure into the enclosure, creating a barrier that stops external combustible gases from entering. This process effectively prevents internal ignition sources from triggering explosions.

Usage Methods:

Flameproof protection relies on the casing’s physical structure and requires standard debugging for operation.

Positive pressure models necessitate an air source, such as instrument air or air compressors. Connecting the air supply to the enclosure and subsequent debugging readies it for normal operation.


Flameproof enclosures provide essential functions like distribution, control, power supply, distant local operation, overload, short circuit, and leakage protection, and light control. However, they have limitations, such as inadequate heat dissipation. Overheating in high-power components can trigger electrical protection. Additionally, issues with explosion-proof touchscreens are unresolved, and installing protective doors for touchscreens may compromise explosion-proof efficacy.
In contrast, positive pressure types not only share some functions with flameproof models but also offer advanced features like chain-type alarms, automatic re-inflation, pressure relief, and remote monitoring. They boast high electrical automation and can cater to explosion-proof needs across various industries. Their superior cooling abilities can manage the heat of large power frequency converters. Unlike flameproof models, they allow direct installation of touchscreens on the enclosures.

Price Point:

The cost difference between flameproof and positive pressure models primarily stems from their material sizes, with positive pressure types generally being smaller.

Through this detailed comparison, users can now discern the unique aspects of both flameproof and positive pressure explosion-proof enclosures, enabling informed choices based on specific needs.



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