They are really set up in the HVAC ductwork and so are brought on to close if they sense smoke. Smoke dampers are frequently made of aluminum and also have a motorized actuator that closes the damper. Backdraft dampers are either gravity or motorized. Gravity backdraft dampers use the pressure https://aircontroldampersforengin35677.blogdanica.com/36656389/an-unbiased-view-of-air-control-dampers-for-engine-sheds