The protection concept for dust hazards is to prevent the dust from entering the enclosure or apparatus. Additional, the maximum surface temperature of the equipment to which the dust can be exposed shall not exceed the ignition temperature of the dust.
The IP (Ingress Protection) rating system provides a means of classifying the degree of protection from foreign bodies and liquids EN 60529:1992 covers electrical equipment and apparatus.
Enclosures shall satisfy the requirements for IP6X, excluding rotating machines.
Enclosures shall satisfy the requirements for IP5X
General principle for ingress protection is as follows:
Equipment for installation in zone 20 or zone 21 should provide at least IP6X
Equipment for installation in zone 22 should provide at least IP5X
Equipment for installation in zone 22 where the dust is electrically conducting (e.g. zinc dust) should be at least IP6X.