GB1200980A - Improvements in and relating to fire dampers - Google Patents

Abstract

1,200,980. Fire dampers. F. W. PANTLAND. 20 Sept., 1968, No. 44717/68. Heading ASA. A fire damper for an air duct comprises a frame in which is pivotally mounted a single damper blade or an assembly thereof, the frame including a peripheral inwardly-extending flange and a web portion extending parallel with the frame wall(s), the or each blade being pivoted at opposite ends or portions and normally biassed to lie in a vertical plane but restrained by thermoresponsive means which, when released, allows the blade(s) to pivot into a vertical position in which it or they overlay(s) the flange and completely close(s) the frame opening. In the rectangular frame illustrated in Fig. 1, longitudinal blades 32 formed with re-entrant V-shaped folds at their upper and lower edges, engage with channels 16 consisting of side flanges 20, 22 and web 18, by means of bearing members in an aperture in the web. Blades 32 pass freely between portions 24, 26 of the flanges in the vertical position, overlap the outer surfaces of the flanges, providing a seal while still allowing clearance for lengthwise heat expansion of the blades; in this position the top and bottom blades abut the upper and lower transoms 14, 14a, and intermediate blades interengage via their V-shaped folds. The assembly is normally restrained horizontally by means of a thermoresponsive vertical control rod 66 linked to pivoted control arms 64 on each blade. The control rod 66 may be operated by a control arm 70 involving a fusible link of Pb/Su/Bi, nylon, PVC, or polypropylene, or movement of the rod may be initiated electrically if required. In a second embodiment (Fig. 8) a twin-tier rectangular damper assembly may be used, and in a third (Fig. 11) a single disc damper for a cylindrical duct is shown.