Round Double Blade Gravity Backdraft Damper

Product Description

The Round Double Blade Gravity Backdraft Damper is designed to prevent reverse airflow in round HVAC and ventilation duct systems. Compared with single-blade models, this damper features two hinged blades that open under forward airflow and close automatically by gravity when airflow stops. The double-blade design helps achieve faster closing, lower airflow resistance, and improved sealing performance.

The damper body is typically made of galvanized steel sheet, while the blades are manufactured from lightweight aluminum alloy for smooth operation and reduced load during opening and closing. An integrated foam sealing strip improves airtightness and helps reduce operating noise.

This type of backdraft damper is widely used in round duct systems, exhaust air systems, smoke extraction branches, and general ventilation applications where reverse airflow prevention is required. For best performance, horizontal duct installation is recommended.

Key Features

• Double Blade Structure  Two hinged blades provide quicker closing response than single-blade models
• Gravity Operated  Blades open under airflow and close automatically by gravity when airflow stops
• Improved Sealing Performance  Foam seal helps reduce leakage and enhances shut-off effect
• Lower Air Resistance  Double-blade design generally offers smoother airflow passage
• Noise Reduction  Sealing strip helps minimize blade impact noise during closing
• Durable Construction  Galvanized steel casing with lightweight aluminum blades
• No Handle or Motor Required  Simple mechanical operation with low maintenance
• Round Duct Compatibility  Suitable for circular duct and pipe systems
• Recommended Horizontal Installation  Designed for stable gravity closing in horizontal duct applications

Applications

• Residential ventilation systems
• Commercial HVAC duct systems
• General exhaust air systems
• Bathroom and toilet exhaust
• Kitchen ventilation branches
• Smoke exhaust branch ducts
• Inline fan outlet protection
• Round duct reverse airflow prevention

Technical Specifications