The DuraFilter FCC - 30 is a filter cartridge used as a main filter in mobile and stationary welding fume extraction systems. It is constructed out of cellulose fibers. The medium is formed into a wedge-shaped filter pattern and molded into a round profile. As a result of this special pleated design and construction, along with the final embossing of filter medium, an equal air flow is created enabling the weight of dust flow to be equally distributed over the filter surface. The welding fume particles are collected on the outside of the filter cartridge. When the pressure drop reaches a certain minimum level, it is automatically cleaned by compressed airshots from the inside of the filter. This makes it a self-cleaning filter.