The Condenser - Blade Design for Dampers

Blade design is important for air control dampers. Learn three blade features to consider when looking for HVAC dampers. Learn more on the MCDLG Newsstand.

Damper Blades and HVAC Design

Blades are important in HVAC design. The damper’s blades will always be in the airstream, whether the damper is open or closed. From the shape of its profile to the position of its seals, the blade’s design will affect the damper’s performance. Each blade feature will increase pressure drop. Blade seals should stop as much air leakage as possible when the damper is closed. Consider these features when designing your dampers.

Blade Profile

Unlike louvers, the profile of a damper blade should have few, if any, features. Damper blades are designed to sit within the airstream when the damper is open. It is important to have a smooth profile to minimize pressure drop as air passes through the damper. A blade profile with lots of features can cause excess static pressure as the air passes over the profile.

Airfoil blades are an excellent choice for control dampers. The airfoil design provides a smooth and aerodynamic surface on both sides of the blade, making it easier for air to pass across the profile. Many single thickness blades have a similar smooth profile, but the blade is flat. The flat profile also lends well to airflow dampers.

Blade Seals

When the damper closes, it should close tightly. This requires blade seals along each edge of the blade. Blade seals are components, typically made from vinyl or polyurethane, which press together and fill in the gaps between blades when the damper closes.

Blade seals are designed to press tightly against the surface of the neighboring blade when the damper closes, so that there is little room for air to pass between the blades. Single thickness blades will typically have seals along the very edge of the blade. The blades’ edges will come together when the damper closes, and the blade seals will overlap. The resulting seal is tight, minimizing air leakage.

Blade Axle

Damper blades will rotate along the blade axle. Blade axles can be set at the center of the blade, so that the full blade rotates along the axis. Or, the axle can be offset to one side, so that it opens like a flap. Off-set axles are common in backdraft dampers, which open with airflow.

There are three common shapes for blade axles: round, square, and pin-lock. Pin-lock axles have grooves along the axle, which match teeth the run along the interior of the blade. These teeth will interlock with the grooves in the axle, creating a tight bond between axle and blade. Blade can slip on the blade after years of constant use, which can cause the damper blade to stop rotating with the actuator. Pin-lock axles minimize blade slippage.

Blade design is important for dampers. Consider the needs of your system when choosing dampers. If you’re not sure what to look for, look at the damper’s blades.

Looking for HVAC dampers? Contact Arrow United Industries. We can help you find the right dampers to meet your airflow requirements!

For more on dampers, check out these other articles on the Newsstand:

• Blades with a Purpose - For Louvers and Dampers
• Control versus Balance - The Difference Between Dampers
• Four Ways to Make Efficient Dampers
• Anatomy of a Damper

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