A disc filter is a type of

water filter A water filter removes impurities by lowering contamination of water using a fine physical barrier, a chemical process, or a biological process. Filters cleanse water to different extents, for purposes such as: providing agricultural irrigation ...

used primarily in

irrigation Irrigation (also referred to as watering) is the practice of applying controlled amounts of water to land to help grow Crop, crops, Landscape plant, landscape plants, and Lawn, lawns. Irrigation has been a key aspect of agriculture for over 5,00 ...

, similar to a

screen filter A screen filter is a type of iltration of waterusing a rigid or flexible screen to separate sand and other fine particles out of water for irrigation or industrial applications. These are generally not recommended for filtering out organic matte ...

, except that the filter cartridge is made of a number of plastic discs stacked on top of each other like a pile of

poker Poker is a family of comparing card games in which players wager over which hand is best according to that specific game's rules. It is played worldwide, however in some places the rules may vary. While the earliest known form of the game w ...

chips. Each disc is covered with small grooves or bumps. The discs (or rings) each have a hole in the middle, forming a hollow cylinder in the middle of the stack. The

water Water (chemical formula ) is an inorganic, transparent, tasteless, odorless, and nearly colorless chemical substance, which is the main constituent of Earth's hydrosphere and the fluids of all known living organisms (in which it acts as a ...

passes through the small passages in between and the impurities are trapped behind. The filtration quality is based on the quantity and size of particles that the filtering element is able to retain. Higher quality filtration simply means cleaner water. This depends on the geometry of the channels, including the size, length, angle, and number of generated intersection points. The discs are typically color coded to denote the level of filtration. Filtration quality is usually measured in

micron The micrometre ( international spelling as used by the International Bureau of Weights and Measures; SI symbol: μm) or micrometer (American spelling), also commonly known as a micron, is a unit of length in the International System of Unit ...

s, based on the smallest size particle filtered. The typical range is from 25 microns for the finest level of filtration to 400 microns for the coarsest. Sometimes the filtration quality is given as the equivalent

mesh size Mesh is a measurement of particle size often used in determining the particle-size distribution of a granular material. For example, a sample from a truckload of peanuts may be placed atop a mesh with 5 mm openings. When the mesh is shaken ...

of a comparable screen filter. Typical mesh sizes range from 40 to 600. When using mesh sizes, 40 is the coarsest and 600 is the finest or highest level of filtration. Disc filters range in size from small units with a 3/4" inlet and outlet used for landscape

drip irrigation Drip irrigation or trickle irrigation is a type of micro-irrigation system that has the potential to save water and nutrients by allowing water to drip slowly to the roots of plants, either from above the soil surface or buried below the surface. ...

systems to very large banks of multiple filters manifolded together used for filtering large volumes of water for agricultural and industrial applications. Some disc filters, especially the smaller ones, must be taken apart and cleaned by hand. Many of the larger ones can be backflushed in such a way that the discs are able to separate and spin during the cleaning cycle. In some cases, a booster pump may be required for backflushing. Disc filters can be used for many types of contaminants, including fine sand and organic matter. However, when used to filter organic matter, they will clog more quickly than a

media filter A media filter is a type of filter that uses a bed of sand, peat, shredded tires, foam, crushed glass, geo-textile fabric, anthracite, crushed granite or other material to filter water for drinking, swimming pools, aquaculture, irrigation, storm ...

and will have to be cleaned more often. One advantage that the disc filter has over the media filter is that it can backflush more quickly with less flush water. Disc filters used in agricultural irrigation are covered by the ISO 9912-2 standard.

History

The disc filter was originally developed in 1936 to filter

hydraulic fluid A hydraulic fluid or hydraulic liquid is the medium by which power is transferred in hydraulic machinery. Common hydraulic fluids are based on mineral oil or water. Examples of equipment that might use hydraulic fluids are excavators and backhoe ...

in the

B-17 bomber The Boeing B-17 Flying Fortress is a four-engined heavy bomber developed in the 1930s for the United States Army Air Corps (USAAC). Relatively fast and high-flying for a bomber of its era, the B-17 was used primarily in the European Theater ...

. In these filters, the discs were made of stainless steel and brass. In the 1960s, this type of filter began to be used in

Israel Israel (; he, יִשְׂרָאֵל, ; ar, إِسْرَائِيل, ), officially the State of Israel ( he, מְדִינַת יִשְׂרָאֵל, label=none, translit=Medīnat Yīsrāʾēl; ), is a country in Western Asia. It is situated ...

to filter irrigation water.

References

Water filters Irrigation {{tech-stub