GB1338828A - Fire damper - Google Patents

Abstract

1338828 Fire dampers GREENWOOD AIRVAC VENTILATION Ltd 3 March 1972 [27 Jan 1971] 3315/71 Heading ASA [Also in Division F4] A temperature-responsive check valve mounted in an air duct 1, 2, of a heating and/or ventilating system comprises flap 7 biassed by spring 9 to a duct-closing position abutting flange 5 of sleeve 4, and normally retained in a position in which air flow is unimpeded by stop assembly 11 pivotally mounted at bolt 13 and consisting of flap-engaging part 11a and further part 11b fusibly connected thereto, e.g. by solder. In the Fig. 1 embodiment bolt 13 passes through both portions 11a, 11b, and rivet 14 restricts pivoting of 11b. On melting of the solder 11 a becomes detached from 11b and rotates about bolt 13 allowing flap 7 to close the duct. Spring clip 15 is positioned to prevent flap 7 from re-opening. Spring 9 is a constantforce flat tension spring extending from housing 10. In Fig. 3, assembly 11 is pivoted above flap 7 at bolt 13 on part 11 having angled opposite end 17. Part 11a has flap-engaging lip 12. No rivet 14 is required. The force tending to separate 11a, 11b is now a shear force instead of a pivoting one. Spring 9 is a normal tension spring. Alternatively the spring may be a compression type, e.g. a leaf spring. Access to the assembly is by cover plate 16 on duct-connecting box 3.