Patent ID: 6610198
Filing Date: 2003-08-26
Classification: B01D

Abstract:
A liquid filter comprising an axially extending housing having an annular filter element extending axially between top and bottom ends and having an inner hollow interior and an outer annular space between said filter element and said housing, wherein said housing has an inlet to said annular space, and an outlet from said hollow interior, wherein liquid is filtered by flowing from said annular space through said filter element into said hollow interior, said annular space being viewable through said housing such that an operator can see the level of liquid in said annular space, said liquid giving off vapor within said housing, a vapor and liquid impermeable outer wrap sleeve around said filter element and having a top end at said top end of said filter element and having a bottom end spaced from said bottom end of said filter element by an axial gap, said sleeve having an outer face facing said annular space, and an inner face facing said filter element, wherein said liquid and said vapor flow from said annular space radially inwardly through said axial gap and radially inwardly through said filter element thereat and also flow axially along said inner face of said sleeve and radially inwardly through said filter element thereat, and when liquid level in said annular space rises above said bottom end of said sleeve, said vapor can no longer flow through said axial gap and is trapped in said annular space above said bottom end of said sleeve due to the vapor impermeability of said sleeve, said sleeve having at least one aperture therein at a given location therealong, a liquid-soluble button initially closing said aperture and then dissolved after a given time by contact with said liquid flowing along said inner face of said sleeve, such that vapor in said annular sleeve may pass through said aperture in said sleeve vacated by said button, and liquid level rises in said annular space.