Whereas
pore size is a measure of the diameter of the largest pore, pore size
distribution is a measure of the range of pore sizes. The range of pore sizes
can be normally distributed, and the spread can be quite narrow (e.g. the ratio
of largest to smallest may be less than 2). On the other hand, pore size
distribution can be very heterogeneous. In the case of large spreads and
heterogeneity, the pore size will be far less predictive of flow rate (either
filtration or capillary) than it will be for a membrane with a narrow pore size
distribution. It is important to note that the pore size corresponding to the
bubble point is not at the middle of the distribution, but is the largest pore.
