US Patent 9302213 Pre-filtration and maintenance sensing for explosion-proof enclosures

A filter system for an explosion-proof enclosure is described herein. The filter system can include a pre-filter assembly located outside the explosion-proof enclosure. The pre-filter assembly can include a pre-filter material configured to control air passing therethrough. The filter system can also include a filter assembly coupled to the pre-filter assembly. The filter assembly can further control the air received from the pre-filter assembly and passing therethrough into the explosion-proof enclosure.