August 13, 2021 Edward Nelson
Within an HVAC system or device involving the flow of air, it can be very beneficial to have control over the free flow of air for various processes. Dampers and louvres are two common components that are found within such systems, both of which permit management over airflow for different purposes. Despite sharing similarities in their use of exterior frames, horizontal blades, and wall placement, each component plays a different role in the overall operations of ventilation systems. In this blog, we will provide a brief overview of dampers and louvres, allowing you to better understand the purposes they serve for HVAC systems and similar apparatuses as well as how they differ from one another.
In their most basic form, dampers are multi-element flow control devices that allow for large amounts of air to be throttled at low pressure. Often, these devices are found within HVAC systems and applications related to furnace and boiler draft control. Dampers may come in varying forms, the two primary designs being parallel and radial types. Parallel-vane dampers in particular have multiple vanes that rotate together, allowing for flow to be throttled through a rectangular opening. Radial-vane dampers, meanwhile, have vanes that are arranged similar to the petals of a flower, allowing for air to be throttled through a circular opening.
Dampers may also be powered in different ways, some being gravity operated while others are motorized. Gravity dampers are typically employed for horizontal fan exhaust operations, often being referred to as shutters. Generally, such damper types are devoid of motors, relying on the pressure provided by the flow of air for opening. Motor driven dampers, meanwhile, are useful for applications where there is a need for a tight seal, or when there is air pressure that needs to be acted against such as when a zone is to be closed off.
Unlike dampers, louvers are devices present within intake or exhaust systems which are capable of protecting assemblies from the infiltration of water. Generally, louvers feature an assembly of fixed blades that are unchangeable, thus any air shutoff would have to be provided by the addition of a damper. As louvers can allow for the passage of air and light, they are more of a regulatory device.
In general, louvers may come in four primary types, those of which are stationary, adjustable, combination, and air measuring variants. Stationary louvers are those that feature blades that are either angled or airfoil-shaped, allowing for the assembly to achieve weather protection and sound attenuation. Adjustable louvers also feature blades that are shaped like airfoils, though they are capable of adjusting. With a combination louver device, some louver blade parts will be set at a specific level of static pressure, while another set will open at another. For protection against corrosion, such louver devices may be all-aluminum in their design. Lastly, the air measuring louver features blades that are placed close together, thus impeding the flow of water for the means of guarding a system.
When comparing the two devices, the main difference that may be seen is how the blades operate. While the blades of an air damper assembly are capable of adjusting as necessary for carrying out standard operations, the blades of louvers are more constant and unchangeable. As louver blades cannot be moved, they exhibit little to no control over the regulation of air flow. Instead, they carry out a standard flow of air while dampers provide more management of air flow for increased regulation. When placed within HVAC systems, both dampers and louvers may be constructed with either aluminum or steel.
If there is a need for managing the flow of fluids and air flow at the same time, it is recommended that one procures and implements dampers and louvers together so that they may work in combination. Generally, the louver will guard the system from water infiltration, while the added damper can permit air shutoff as required. As both devices are subject to constant exposure to varying temperatures and substances during standard operations, it is crucial that one regularly inspects and maintains them to ensure their continued health and performance.
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