Dampers stop or regulate the flow of air inside a duct to provide airflow control, energy efficiency, air pressure balance and safety.
1. The role of Dampers
Dampers play a crucial role in the functionality of industrial ductwork as they are designed to control the flow of air or flue-gas within the ducts. The primary purpose of most dampers is to act as shut-off dampers. This means they are either fully open or fully closed depending on the operational requirements. However, some dampers are specifically installed to modulate the gas flow, allowing them to function in various partially open positions. This variability in damper functionality caters to different operating scenarios and provides flexibility in managing the flow of air or flue-gas through the duct system.
2. Dampers and Their Types
Common damper types include louvers, butterflies, and guillotines, with less conventional options like poppet and diverter dampers.
Figure 1 : Common damper types
3. Optimal Damper Placement
Guillotine dampers, designed primarily as shut-off dampers, demonstrate optimal performance when their blades are maintained in a vertical plane. Louver dampers, equipped with rotating blades, serve as either shut-off or flow-regulating dampers. Placing dampers upstream of expansion joints is recommended to enhance joint service life and shield them from extreme temperatures. Strategic placement in low-stress regions, particularly adjacent to expansion joints, helps prevent warping and potential impairment of damper function.
4. Structural Considerations
Given their considerable weight and exposure to wind and snow loads, dampers are most efficiently located near duct supports. Damper frames may lack the strength required to handle significant shears and moments, necessitating meticulous consideration in the design process. Direct support of ductwork from dampers is discouraged to mitigate potential issues arising from inadequate frame strength.
5. Dead Legs and Associated Concerns
Dead legs are the denoting sections of duct open only at one end due to closed dampers. They should be minimized because stagnant flue-gas in dead legs may accelerate corrosion and induce undesirable thermal gradients. Thoughtful design considerations, such as slope orientation and additional dampers with a seal air system, can effectively address challenges associated with dead legs.
Figure 2: Example of a Dead Leg
6. Toggle Duct Sections
The placement of dampers in toggle duct sections is discouraged due to potential adverse effects on damper alignment and support design. Toggle duct sections, designed for considerable movement, introduce complications in damper support and alignment owing to their rotational movements.
In summary, the critical importance of thoughtful damper placement, meticulous structural considerations, and strategic design choices are critical to ensure the effective and reliable operation of duct systems. The multifaceted nature of these considerations highlights the intricate balance required to optimize the performance and longevity of dampers within complex ductwork configurations.
Novelty Structures offers various kind of damper fabrications for industrial projects.