GB861643A - Improvements in an air flow control damper - Google Patents

Abstract

861,643. Valves. BARBER-COLMAN CO. Feb. 24, 1958, No. 5891/58. Class 135. [Also in Group X] The control of air flowing through a duct 11, Fig. 1, is effected by a damper consisting of strips 17 of flexible material each supported on a pair of rods 18, 19 for folding movement into and out of edge-to-edge engagement to close or variably open the duct. The rods 18 are fixed whilst rods 19 are disposed in slots and movable transversely of the duct by a rack and pinion 27 connected to a handle 29. The strips 17, Fig. 8, are made of extruded rubber, and the rods are inserted through the hollow beads; the beads may be longitudinally split and each strip may increase in thickness from the centre towards the beads or have a weakened centre to facilitate the folding action. Each strip is made wider than the maximum distance between the rods. In the fully open position the two beads of each strip are in lateral contact and present a smooth diverging surface for the passage of air therethrough. The outside beads of the end strips seal against the duct when the damper is closed. The ends of each strip may be reinforced by webs to prevent longitudinal bending. Material such as leather, canvas, fabrics impregnated or coated with rubber, and polyethylene may also be used for the strips. Each strip may be formed from a flattened tube with the central areas sealed or cemented together. In another form sheet-material is utilized with the edges curled round the rods and held in slots therein or secured thereto by split tubes; the rods may be of square section intermediate the ends and covered by extruding or moulding the strip thereon. The intermediate rod sections may be pear-shaped, the strips being cemented thereto. The damper may be operated by movement of either or both rods.