Method of filtering grease-laden air

A grease filtering method for kitchen ventilating systems and the like, said method comprising the steps of providing a housing that is elongated in the X and Y directions and less than 2 inches in the Z direction so that the housing will fit in the space normally provided for mesh-type filters in a kitchen ventilating system, said housing forming closed top and bottom walls lying substantially in X-Z planes, closed side walls lying substantially in Y-Z planes, and front and rear walls lying substantial in X-Y planes, said front wall forming a multiplicity of spaced entrance openings which are uniformly elongated in the Y direction and relatively narrow in the X direction, each of said entrance openings formed by a pair of edges of said front wall elongated in the Y direction on opposite sides of the opening, said rear wall froming a multiplicity of exit openings each of which is midway between a pair of adjacent entrance openings, said exit openings also being uniformly elongated in the Y direction and relatively narrow in the X direction, a multiplicity of interior baffles lying substantially in Y-Z planes within said housing, each of said interior baffles comprising a single sheet of metal extending from a line midway between an adjacent pair of said exit openings on said rear wall to a line midway between an adjacent pair of said entrance openings on said front wall so that opposite sides of each of said interior baffles are exposed to said ajdacent pair of entrance openings, a multiplicity of entrance baffles equal to the number of entrance openings extending into said housing from the elongated edges of said entrance openings, each of said entrance baffles extending from one of the elongated edges of one of said entrance openings toward the side wall or the interior baffle that is closest to said entrance opening with the rear edge of each entrance being spaced farther away from said closest sidewall or interior baffle than the other elongated edge of its entrance opening, the entrance baffle originating at the entrance opening edge in said front wall that is farther away from said closest side wall or interior baffle and extending toward said closest side wall or interior baffle and extending toward said closest side wall or interior baffle at an acute angle relative to said front wall so as to deflect an entering exhaust stream toward said closest side wall or interior baffle as the exhaust stream passes rearwardly through said housing, and a multiplicity of exit baffles equal to the number of entrance baffles extending into said housing front the elongated edges of said exit openings, each of said exit baffles extending from an elongated edge of one of said exit openings toward the opposite elongated edge of the same exit opening at an acute angle relative to said rear wall so as to deflect the exhaust stream moving rearwardly from each entrance opening in the forward direction away from said rear wall before the exhaust stream is discharged through said exit opening, said bottom wall forming a multiplicity of drain openings adjacent said front wall and spaced away from said entrance openings in the X direction;

• passing an exhaust stream containing condensable grease and oil through said entrance openings and rearwardly between each of said entrance baffles and the adjacent Y-Z side wall or interior Y-Z baffle, then forwardly between each of said entrance baffles and the adjacent exit baffle, and finally rearwardly between each pair of exit baffles on opposite edges of each exit opening and out through the exit opening;
• and collecting extracted liquids drained through said drain openings below the bottom wall of said housing.