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Why is the largest-hole screen placed at the top of a sieve stack?
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filtration
Tap water filtration system.
In a sieve stack used for filtration, the screen with the largest hole size is placed at the top to facilitate the systematic separation of particles by size.
When a mixture of particles is placed on the top screen and the assembly is agitated, the largest particles are retained by the coarsest mesh, while smaller particles pass through to the subsequent, finer screens below. This arrangement ensures that particles are distributed among the sieves according to their specific diameters, allowing for an efficient and orderly classification of the material.1