Q. Illustrate Concept of filter design?

The material used for filter should satisfy the following normal criteria

a. Filter material is more pervious than the base material / core material

b. Filter material has such gradation that the particles of base / core material do not migrate through. Such migration can clog the voids and fail the very purpose of a filter.

c. Filter material helps to form natural graded material in the zone of base material / core material.

d. Normally, natural material to satisfy the above requirements is not readily available in nature. A graded filter design consists of layers of different grades.

e. To minimise segregation, each grade of the filter material is normally very uniform in size.