12 inch Backdraft Damper

Sizing a 12 inch Backdraft Damper Into a Big Run

At twelve inches everything about a damper is bigger, including the consequences of getting it wrong. An open duct this size is a substantial hole in a building. With the fan off it moves cold air, odour and dust in the wrong direction continuously. On a room built around a pressure relationship, that undoes the whole design. The two blades here are correspondingly large plates, which is why the hinge arrangement matters. Each blade has its own hinge, so a blade that catches on debris does not hold its partner open with it. Galvanized steel keeps plates this size rigid enough to seat properly for years in a humid duct. A neoprene perimeter gasket takes the closure. On a plate this size that is the difference between a soft thud and a bang carrying through a building.

Installing a Duct Insert of This Diameter

The assembly pushes into the duct rather than mounting on a flange, which at this diameter saves genuine work. There is no transition piece to fabricate and nothing to line up beyond the duct itself. It installs in any orientation. Two things deserve attention at this size. Support the duct on both sides of the damper properly. A twelve inch run carries real weight, and a sagging duct distorts the housing until the blades no longer seat. The second is access to it afterwards. A damper buried in a ceiling void where nobody can reach it will eventually stop sealing and nobody will know. Atmosphere quote an opening requirement of four to eight hundredths of an inch of static pressure. A correctly specified twelve inch fan clears that easily at speed. Confirm it at low speed too. Check the swing and wipe the sealing face at every filter service.

Key Features

• Duct size: Twelve inches, the largest in the Atmosphere damper range
• Why it matters: An open duct this size is a substantial hole in a building
• Blades: Two large plates, each on its own independent hinge
• Hinge design: A blade that catches cannot hold its partner open
• Body: Galvanized steel, stiff enough to keep large plates seating
• Seal: Neoprene perimeter gasket, which softens the closure
• Mounting: Inserts into the duct, with no transition piece to fabricate
• Orientation: Any position, on a horizontal run or a vertical riser
• Support: Hold the duct both sides so the housing cannot distort
• Access: Leave it reachable, since a buried damper fails unnoticed

Technical Specifications