Introduction To Air Duct Backdraft Dampers

Introduction to Air Duct Butterfly Backdraft Dampers

Air duct backdraft dampers, also known as check valves or one-way valves, are devices designed to prevent the backflow of air within ductwork. Their primary function is to ensure that air flows in only one direction, thereby preventing reverse airflow and protecting fresh air systems or indoor air from contamination caused by backflow. This enhances the efficiency of fresh air systems while safeguarding other ventilation ducts and equipment.

Structure and Working Principle

The working principle of air duct backdraft dampers is straightforward: when air flows in the intended direction, the damper flap is pushed open by the airflow, allowing air to pass through with minimal pressure. Conversely, when outdoor air attempts to flow backward due to pressure differentials, the flap closes under the force of a spring, effectively blocking reverse airflow. In the absence of airflow within the duct, the flap remains either closed or partially open, resulting in a design that allows the damper to operate automatically without external power, simplifying system structure and enhancing reliability while minimizing failure rates.

Main Materials and Components of Air Duct Butterfly Backdraft Dampers

Air duct Butterfly backdraft dampers typically consist of several key components, including the damper body, flap, pivot shaft, spring, and sealing ring. The cylindrical damper body is generally constructed from cold-rolled steel, galvanized steel, stainless steel, or plastic, with thicknesses ranging from 0.9 to 2.5 mm. The damper flap is usually made from aluminum alloy sheets, with thicknesses typically between 0.5 and 1.5 mm. The pivot shaft and spring are selected from stainless steel, with the pivot shaft typically being a stainless steel rod with a diameter of 5 to 10 mm.

Manufacturing Process of Metal Air Duct Butterfly Backdraft Dampers

The damper body is formed by rolling metal sheets into a cylindrical shape, followed by welding via laser or argon arc techniques. Post-welding, the seams are subjected to a smoothing process, after which specialized equipment is used to create reinforcing ribs within the damper body. These ribs not only enhance the structural integrity of the damper when installed but also fortify the cylindrical shell. Some air duct backdraft dampers require flange structures at both ends for connection to the ductwork. The internal ribs, which protrude inward, create a fixed seal with the damper flap. The flap is fabricated by cutting aluminum alloy sheets into two semicircles and constructing a hinge connection structure, allowing for free rotation once assembled.

Surface Treatment of Metal Air Duct Backdraft Dampers

For backdraft dampers made from cold-rolled steel, a powder coating is applied to the surface, providing corrosion resistance. The color of the coating can be customized according to client specifications. For backdraft dampers made from stainless steel, the weld seams require polishing treatment to ensure a smooth finish.

Common Specifications and Applications of Air Duct Backdraft Dampers

Air duct backdraft dampers come in standard sizes, typically including 4 inches, 6 inches, 8 inches, 10 inches, and 12 inches in diameter. They are widely utilized in various applications where fluid backflow prevention is crucial, including fresh air systems and air exchange systems in commercial centers and office spaces. The backdraft damper plays a vital role in preventing reverse airflow, making it a common component in fresh air systems.

In residential fresh air systems, particularly in bathrooms and kitchens, backdraft dampers prevent the backflow of air laden with cooking fumes, thereby protecting indoor air quality and facilitating better management of temperature and humidity levels.