Also referred to as screening meshes, screens keep back solids that may cause damage to pumps in pumping stations and process water feed stations or block water flow downstream such as in waste-water ducts and sewage-treatment plants. Screens keep turbines running interruption-free in hydroelectric power plants and prevent articles such as driftwood or household refuse being carried further downstream in watercourses.
Screens are usually made of common steel sheet. There are also specialised profiles available for special applications, which may, for example, stop large items while allowing grass to pass through. Suitable reinforcements fitted in the necessary numbers ensure that the screen is kept at the intended gap between elements across the area of the screen.
In most cases, ordinary hot-dip galvanised steel will be enough to prevent screen corrosion. We also supply screens in stainless steel (1.4301, 1.4571) or other highly corrosion-proof materials in special applications involving high exposure to salts or other chemicals.
Usual gap widths
|Pumping stations||40 - 100 mm|
|Waste-water facilities||20 - 50 mm|
|Barrages||50 - 150 mm|
|Hydroelectric power plants||20 - 70 mm|
|Process water extraction||20 - 40 mm|
Practice has shown a screen tilt angle of 15° to be ideal for cleaning, whether manually or by rig.
Sluice and gate screens may be used instead of fixed screens where special conditions are to be expected, such as increased ice drift or for opening a sluice as an emergency overflow.
See also: Screen Cleaning Machines.