Screen filter Photo: L SchwanklThe degree of filtration is expressed as mesh size or equivalent mesh size. The mesh size is the number of openings per inch. For example, a 200-mesh filter has 200 openings per inch.
Centrifugal sand separator. The shaded arrows show the sand; the white arrow shows the water. Source: Courtesy Claude Laval Corporation.A centrifugal sand separator, often used for pre-filtration, removes larger particles of sand.
Figure 11. Sand media filter during the filtration and backflushing processes. Source: Courtesy Claude Laval Corporation.A sand media filter consists of tanks filled with silica sand or crushed granite. Contaminants are filtered from the water as it flows through the filtering media (fig. 11).
Screen filters used in conjunction with sand media filters Photo L. SchwanklA pressurized screen filter may be the most economical choice for groundwater filtration, since it is effective at removing inorganic material.
Suction screen pre-filter with water jets to keep the screen clean. Photo: L. SchwanklA suction screen filter uses a coarse mesh (sizes range from 10 to 30) for prescreening; it is placed at the inlet of the pump intake pipe where surface water is being pumped.
Flushing of a drip tape lateral Photo: L. SchwanklPeriodic flushing is required to prevent clogging from sediments, particularly along the lower part of the drip line. A 200-mesh filter will not remove particles of fine sand, silt, and clay or fine particles of algae.
Gravity flow screen filter used in a citrus orchard Photo: L. SchwanklA gravity filter can be used with water that has a low to medium concentration of suspended solids (10 to 100 ppm). With this device, the water flows by gravity through a screen with a mesh size of 100 to 200.
Disc filter. Photo: Jack Kelly ClarkA disc filter consists of a stack of discs, each with a series of microscopic grooves. The dimension of the grooves determines the effective mesh size of the filter, ranging from 40 to 600 mesh. Water is filtered as it flows through the grooves.
