GB1298458A - Improvements in fire dampers for heating and/or ventilation systems - Google Patents

Abstract

1298458 Fire damper ANDREWS-WEATHERFOIL Ltd and G T K DEAN 2 March 1970 [3 March 1969] 11304/69 Heading A5A A fire damper for heating or ventilating ducts comprises two or more flaps pivotally mounted about separate axes within a duct so as to be movable from a closed position in which each flap closes off a portion of the duct and the peripheral parts of each flap overlap the edge of the duct outlet or the adacent flap or flaps so that the duct is completely closed off by the flaps, and an open position where they are held by detent means away from the closed position. Figs. 1, 2 show a fire damper in open and closed positions respectively. The damper comprises flaps 13, 14, 15, 16 pivotally mounted across outlet structure 12 of air duct 10. Flap 13 is bingedly mounted by means of rod 17 attached along its lower edge (Fig. 4) and having projecting ends which engage in slot 18 in the side walls of duct 10. Flaps 14, 15, 16 are pivotally mounted by virtue of their lower edges resting on the side flanges of 12, and are retained in position by means of rods 21 which extend across and beneath outlet 11 and pass into slots 20 in two spaced brackets 19 on each flap. The upper free edges of flaps 13-16 are connected by linking structure 22 comprising beam 23 having at one end cross bar 24, (see Fig. 4). Lugs 25 extend down from bar 24 and are formed with slots 26 through which passes rod 27 mounted on lugs 28 on flap 13, and further lugs 29 along beam 23 each formed with slots 30 receive rods 31 carried by lugs 32 on each of flaps 14, 15, 16. The flaps can thus pivot downwards under gravity from the open position of Fig. I to the closed position of Fig. 2 in which each flap overlaps an adjacent flap. A detent device for normally retaining the flaps in the open position comprises two rods 33, 34 joined by fusible link 35, the lower end of 34 engaging lug 36 on structure 12 and the upper end of 33 engaging lug 37 on flap 15. In the Fig. 5 modification (not shown) the lower edge of each flap has projections 38 which engage slots 39 in the side walls of duct 10 to provide an alternative pivotal mounting.