Cooperating filter disk units with fingered surfaces

A disk-type filter comprising:

• a housing having an inlet connectable to an upstream pipe and an outlet connectable to a downstream pipe;
• and
• a stack of filter units disposed within said housing for separating solid particles from a fluid flowing between filter units in said stack of filter units from an upstream side of said stack of filter units to a downstream side thereof,
• characterized in that said stack of filter units comprises a plurality of co-operating filter units defining a plurality of paired co-operating filter surfaces, comprising first and second surfaces each defining a plurality of fingers, said fingers defined by said first surface being arranged in registration with said fingers defined by said second surface, the exteriors of said fingers defined by said first and second surfaces communicating with either one of an upstream side and a downstream side and the interiors of said fingers defined by said first and second surfaces communicating with the other one of said upstream side or downstream side, spaces being defined in association with said fingers defined by said first and second surfaces and being disposed in registration so as to define channels, which permit particulate matter to become disengaged with said upstream side of said fingers defined by said first and second surfaces, the fingers of each unit being joined at a location radially outward of their base.