Air Clear Pre-filter Systems are utilized when tars, stone dust, talc, oils, solid particulate, etc are present in the process exhaust stream. The Pre-filter protects the main filters in the Air Clear Coalescing Fiberbed Filter Mist Collector Systems.rnrnAir Clear Pre-filter Systems have also been used on dirty applications that require an Oxidizer System, such as, RTO, Catalytic, and Thermal Systems. Air-Clear has several Pre-filter systems operating on our oxidizer systems and other air pollution control manufacturer’s oxidizers.