Abstract: Incoming air passes through one or more orifices in an expansion head forming small jets which impinge upon a downwardly facing cylindrical wall for moving water droplets and the like into a sump. A curved shield located above the cylindrical wall serves to move the incoming air upwardly in a relatively uniform billowing mass. A filter cartridge includes, in the order described from the lowermost to the topmost, at least three individual cells. The first cell contains cotton waste for absorbing water, oil, particulate matter and the like. The second cell contains a material for capturing such things as oil aerosols, for example. The uppermost cell, again, contains cotton waste for removing particulate matter, such as dust from the molecular sieves, for example, and any residual moisture. The cells are spaced from one another by spring-loaded means to maintain the separation. The spaced relation of the cells prevents channeling of pressurized air through the cells.