Patent ID: 7087166

Claim:
A filter element comprising an upstream filter having a top end cap and a bottom end cap and a downstream filter having a top end cap and a bottom end cap, wherein the upstream filter and the downstream filter have cylindrical shapes such that the downstream filter is received within an interior of the upstream filter, wherein radially outer edges of the top and bottom end caps of the downstream filter are in respective contact with radially inner edges of the top and bottom end caps of the upstream filter, wherein an upper surface of the top end cap of said downstream filter has a filtrate outlet for fluidly connecting an interior of said downstream filter to the outlet of a housing, and wherein the radially outer peripheral edge of the bottom end cap of the downstream filter includes a twist-lock groove consisting of an axial groove and a circumferential groove extending from the axial groove, and wherein the radially inner peripheral edge of the lower end cap of the upstream filter includes a projection that is receivable within the axial and circumferential grooves of said twist-lock groove, whereby when the upstream filter is rotated and moved downwardly, said bottom end cap of the upstream filter is detachably fixable to the bottom end cap of said downstream filter.