Heat activated ventilation duct flap valve - has flexible arched section which fits flush in bore chamber with heat actuated torsion closure spring

摘要

With a fire or temperature actuated sprung closure action, the hinged (10) circular flap (5) valve is used at strategic points in ventilation ducts (11) or similar and constitutes an automatic barrier to fire or fume propagation. The flap is top hung with e.g. a torsion spring (9) for closure, with a flexible construction of an original arched half round cross-section. This pre-curvature enables the flap to be set flush in a duct length (1) of increased dia. permitting unobstructed duct flows when the flap is at repose. In detail the flap may be of metal sheet (5) with a thick thermo-insulating padding (4), the increase in duct dia. equalling padding thickness. Fusible plastic chains (8) may maintain pre-curvature and hold the flap at repose. This action is augmented by a fusible pastille (14) catch. A latch (6) may hold the flap at closure against a compressible seal.