Tunnel escape system for smoke or fumes - has temperature responsive escape flaps with fusible locking washers

摘要

The ventilators are spaced at intervals along the tunnel and are joined by a duct to an extraction fan. The ventilators are fitted with damper plates (7) which are hinged so that they can be opened by an predetermined amount. Each damper plate may be locked by means of a nut and bolt. The bolt passes through a slot in the plate. The damper plate is urged fully open by the action of a spring (9). A fusible washer is fitted under the bolt head. Should the temperature rise due to a fire, the bolt will no longer be tight and the spring causes the plate to open wide.