What is “Uniformity coefficient”?
The uniformity coefficient of sand is defined as a ratio: the size at which 60 percent (by weight) of a sand sample passes through a sieve (in other words 60 percent of the sand is finer than a given size) divided by the size at which 10 percent of the same sample (by weight) passes through a sieve (10 percent is finer than a given size). A UC of 1 indicates all the particles are the same size. As the number goes up the size differentiation becomes greater and the quality of the sand becomes less desirable for use in a slow sand filter. back to top 14.