The police filter is used to collect small amounts of unwanted solid particles such as rust, dross, and filtering powder as well as small solid particles accidentally found in other liquids such as plant oil, beer, juices and syrup. The small particles may have escaped the previous filtration processes. The filter serves as a safety function hence the name police filter.
The Police filter uses a layer of filter elements made of needled material or non-woven heat sealed material to filter liquids. It has a selectivity of between 5 and 25 mkm.