Fire damper for ventilation ducting - has fusible plug holding sprung cranked lever for automatic or manual operation

摘要

The damper blade (14) pivots on a shaft (13) within a casing (10) in a run of ventilation ducting. The shaft projects outside the casing and is linked to an operating lever (18). a spring (19) tends to close the damper. A knob (40) on the other end of the lever (18) rests against a cranked lever (30) which holds the operating lever (18) in the open position. The cranked lever (30) pivots on a pin (29) which is kept in place by a fusible plug against the force of a spring. When the plug melts the pin moves axially and frees the cranked lever which allows the operating lever to close. Manually the cranked lever can be pivoted out of the way to allow the operating lever to close.