Patent ID: 8678202

Claim:
A composite media formed from at least three layers of media material from an upstream direction to a downstream direction, namely Layer A, optionally Layer B, Layer C, and Layer D, the layers having characteristics as follows: Layer A comprises polymeric media material having a mean pore size of greater than about 10 μm, and relative to a layer immediately downstream of Layer A, Layer A has: (a) a higher porosity, (b) a larger pore size, (c) a larger mean fiber diameter, (d) a higher Frasier permeability, and (e) a lower contaminant removal efficiency; Layer C comprises polymeric material comprising nanofibers and having: (a) a mean pore size (M) of 0.2-10 μm; (b) a maximum pore size (M M ) to mean pore size ratio (M M /M) of less than about 3, (c) a mean fiber diameter of 0.1-1.0 μm, and (d) a basis weight of greater than about 20 gsm; and Layer D comprises polymeric material having a mean pore size of greater than about 10 μm and provides support for the preceding layers, and relative to a layer immediately upstream of Layer D, Layer D has; (a) a higher porosity, (b) a larger pore size, (c) a larger mean fiber diameter, (d) a higher Frasier permeability, and (e) a lower contaminant removal efficiency; wherein the composite media has a permeability of 3-40 cfm.