A particulate air filter is a device composed of fibrous, or porous materials which removes solid particulates such as dust, pollen, mold, and bacteria from the air.
paper element
A fuel filter is a filter in a fuel line that screens out dirt and rust particles from the fuel, and is normally made into cartridges containing a filter paper
hydraulic filtration is used to filter hydraulic fluid in a hydraulic system when adding new fluid, charging fluid, or flushing the hydraulic system before adding new fluid