Filter cartridge for suspended particles

Claim 1

A filter cartridge for filtering suspended particles from a fluid passing through the cartridge, comprising: a frame defining an inlet opening for admitting fluid to be filtered and an outlet region for permitting filtered fluid to leave the frame; grid means positioned in the frame and having peripheral portions embedded therein; an elongate filter web positioned in the frame and having peripheral portions embedded therein, the web being supported and backed by the grid means and having one main surface facing towards said inlet opening and its other main surface facing towards the grid means and said outlet region so that fluid to be filtered passes through the web in the direction from said one main surface towards said other main surface, the grid means being elongate and comprising a plurality of essentially planar grids extending substantially parallel to one another away from the inlet opening and secured together end-to-end by clamps, and the web being folded along a plurality of fold regions spaced apart along the web to give it a pleated configuration with the pleats extending between respective pairs of adjacent grids, at least one of said grids being formed with a projection protruding out of the plane of the grid into the space between successive pleats of the filter web to maintain the grids and said successive pleats in spaced relationship.