A damper is a valve or plate that stops or regulates the flow of air inside a duct, chimney, VAV box, air handle or other air handling equipment. Its operation can be manual or automatic. Manual dampers are turned by a handle on the outside of a duct. Automatic dampers are used to regulate airflow constantly and are operated by electric or pneumatic motors.
In a chimney flue, a damper closes off the flue to keep the weather out and warm or cool air in. This is usually done in the summer, but also sometimes in the winter between uses. In some cases, the damper may also be partly closed to hep control the rate of combustion.
Damper are available for a wide variety of applications in round ductwork, where loe-leakage isolation can be obtained from 90 t0 99.9% depending on the seal arrangement.
Tri shaft seals provide a low-cost, heavy-duty design that is suitable for applications uo to 700 C gas temperature. Dampers are equipped with a standard outboard bearing and a frame-mounted shaft seal arrangement. This categorization allows for packing replacement without bearing removal