These semi self-cleaning filters are designed to remove solids from water with only occasional cleaning attention. They use a wedge wire, 304 stainless steel screen set in a parabolic shape to take advantage of the Coanda effect (see below). This wedge wire shape encourages solids-free water to drop between the screens and solids to be left on the surface. The solids are then pushed toward the waste trough and automatically washed into a waste tank. Rubber couplings with clamps are included. Not recommended for use with salt water.
The Coandă effect is the tendency of a fluid jet to stay attached to a convex surface. As described by the eponymous Henri Coandă in different patents: “the tendency of a jet of fluid emerging from an orifice to follow an adjacent flat or curved surface and to entrain fluid from the surroundings so that a region of lower pressure develops.” The pressure effect, which is usually not indicated, is fundamental for the comprehension of the Coandă effect.
Source: Wikipedia