Importance

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Abstract

A fail-safe closed damper for installation in a system of ducts. The damper includes at least one damper blade connected to a spring-loaded shaft. A power-actuated unit is employed to disengage a coupling which interconnects the spring-loaded shaft to an operating linkage. The use of the power-actuated unit ensures that the damper will be tripped at the appropriate predetermined temperature and will not be affected by the large frictional forces imparted on the components of the damper by the biasing spring or by such external factors as dust, humidity and dirt. The damper employs a sensor having dual sensing devices and which is centrally disposed in the duct to ensure receipt of a representative sample of airflow. The damper further includes a damper blade position indicator for sensing whether the damper blade is open or closed.

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First Claim