ABSTRACT
Given a fluid, what filter medium should we use to use clarify it; to recover solids from it; or to sterilize it if it is otherwise particle free? Should we use a thick or thin filter medium? What flow-averaged pore diameter do we need? In classifying filter media as coarse, fine, in between, the arbitrary and often misleading micron rating has evolved. The micron rating, determined using a standardized filtration test, names the particle diameters stopped with great efficiency under the conditions of that test. As we saw in Chapter 6, however, there are many different ways of expressing filtration efficiency, and, of course, the rating changes when the tests conditions change.
