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 of plants) is the practice of applying controlled amounts of water to land to help grow crops, landscape plants, and lawns. Irrigation has been a key aspect of agriculture for over 5,000 years and has bee ...

, similar to a

screen filter Filter screen A screen filter is a type of water purification using 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 ...

, 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 Card game#Comparing games, comparing card games in which Card player, players betting (poker), wager over which poker hand, hand is best according to that specific game's rules. It is played worldwide, with varying rules i ...

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 is an inorganic compound with the chemical formula . It is a transparent, tasteless, odorless, and Color of water, nearly colorless chemical substance. It is the main constituent of Earth's hydrosphere and the fluids of all known liv ...

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 (English in the Commonwealth of Nations, Commonwealth English as used by the International Bureau of Weights and Measures; SI symbol: μm) or micrometer (American English), also commonly known by the non-SI term micron, is a uni ...

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 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 surfac ...

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 A booster pump is a machine which increases the pressure of a fluid. It may be used with liquids or gases, and the construction details vary depending on the fluid. A gas booster is similar to a gas compressor, but generally a simpler mechanis ...

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 (water), 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, i ...

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 backho ...

in the

B-17 bomber The Boeing B-17 Flying Fortress is an American four-engined heavy bomber aircraft developed in the 1930s for the United States Army Air Corps (USAAC). A fast and high-flying bomber, the B-17 dropped more bombs than any other aircraft during ...

. 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, officially the State of Israel, is a country in West Asia. It Borders of Israel, shares borders with Lebanon to the north, Syria to the north-east, Jordan to the east, Egypt to the south-west, and the Mediterranean Sea to the west. Isr ...

to filter irrigation water.

References

Water filters Irrigation {{tech-stub