A device installed in ducts to close automatically upon detecting heat is known as what?

A device installed in ducts to close automatically upon detecting heat is known as a fire damper. Fire dampers are crucial for maintaining the integrity of fire-rated walls and preventing the spread of fire and smoke through ductwork. They are designed to automatically close when the temperature in the duct reaches a predetermined level, which indicates a potential fire condition. This closure helps to contain the fire within a specific area and limits the amount of heat and smoke that can travel through the duct system, thereby protecting other parts of the building.

In contrast, smoke dampers are intended to control the movement of smoke through the ductwork, but they may not necessarily react to heat in the same manner as fire dampers do. Exhaust dampers typically regulate airflow from a building's exhaust systems rather than serve a fire safety function. A safety valve is a device used for pressure relief in various systems and does not pertain to ductwork or fire protection measures.