Abstract: In a fluid passageway a filter panel is selectively moved out of its normal position extending across the fluid passageway to a dumping position out of the fluid passageway such that particulate matter collected thereon is removed responsive to the movement of a baffle plate from a normal position out of the fluid passageway into a position blocking the fluid passageway. Thereby passage of air through the fluid passageway is prevented during the time the filter panel is out of its normal position. In a preferred embodiment a linking mechanism connects the baffle plate and filter panel together so that movement of the baffle plate to the blocking position causes the filter panel to drop to a dumping position and return of the filter panel to its filter position causes the baffle plate to drop to its normal position. The whole sequence is instituted responsive to buildup of particulate matter on the filter panel.