Backdraft Dampers
Permit airflow in one direction and prevent a reverse flow with Kelair's high-quality backdraft dampers
Download our BrochureKelair Dampers Brochure
Engineered to allow airflow in one direction and prevent reverse airflow
Industrial backdraft dampers fulfill the same mission as their commercial counterparts: they allow airflow in one direction and prevent airflow in the opposite direction. Another way to say this is that these dampers allow for air intake or exhaust/pressure relief while automatically preventing the backflow of air. Kelair’s backdraft ventilation dampers are manufactured to withstand environments with high back pressures and high airflow velocities. These types of industrial backdraft vents are supplied with counterbalanced weights, mounted externally (which are easily field adjustable), they can be gravity balanced, or even paired with actuation if desired.
*Operational testing and calibrating are completed at the factory prior to installation. Questions about installing a Kelair damper at your facility? Contact a Kelair representative near you for answers.
Where Industrial Backdraft Dampers Protect Your Ventilation Systems
Kelair backdraft gravity dampers are custom-engineered for industrial and commercial ventilation systems where maintaining airflow direction, system pressure, and air quality is critical. By allowing air to move in one direction and automatically preventing reverse flow, these dampers help protect equipment, improve energy efficiency, and maintain safe operating conditions.
Industrial Exhaust Systems
In industrial exhaust systems, including power generation, petrochemical processing, and manufacturing facilities, ventilation backdraft dampers prevent the reverse flow of hot gases, particulate, and potentially hazardous fumes. During fan shutdown or system pressure changes, this protection helps reduce contamination, protect downstream equipment, and maintain system integrity.
HVAC & Building Ventilation Systems
In HVAC and building ventilation systems, backdraft dampers play a key role in pressure management and energy efficiency. By preventing conditioned air from escaping and blocking unwanted outside air from entering, they help maintain building pressure balance while reducing heating and cooling losses. This results in improved indoor air quality and lower long-term energy costs.
Clean Rooms, Laboratories & Food Processing
Specialized environments such as clean rooms, laboratories, and food processing facilities rely on backdraft dampers to maintain strict pressure differentials. By preventing cross-contamination and controlling airflow direction, these systems help protect sensitive processes, meet regulatory standards, and ensure consistent product quality.
Heat Exchangers & Process Systems
Backdraft dampers are also used in heat exchangers, solar heating systems, and process ventilation equipment, where reverse airflow could reduce efficiency or introduce contaminants. In these applications, maintaining proper airflow direction is essential for both performance and equipment longevity.
Flexible Installation & Configuration
Kelair backdraft dampers are designed for flexible installation, supporting both horizontal and vertical orientations. For applications requiring tighter shutoff or specific mounting constraints, butterfly-style configurations can be incorporated to meet performance and space requirements.
Backdraft vs. Pressure Relief vs. Barometric Dampers: Which Type Fits Your System
Although backdraft, pressure relief, and barometric dampers may appear similar, each serves a distinct function depending on airflow direction, pressure conditions, and system requirements.
Backdraft Dampers
Backdraft dampers (also known as gravity dampers) are designed to allow airflow in one direction while preventing reverse flow. They operate using gravity or counterbalanced blades that automatically close when airflow stops or reverses, making them ideal for general ventilation and exhaust systems where backflow prevention is the primary concern.
Pressure Relief Dampers
Pressure relief dampers are a specialized type of backdraft damper designed to open only when system pressure exceeds a predetermined threshold, often calibrated to maintain consistent pressure across varying airflow conditions. These dampers help protect equipment and ductwork from overpressure situations and are commonly used in enclosed systems, industrial exhaust, and process ventilation where pressure control is critical.
Barometric Dampers
Barometric dampers are used to regulate draft and maintain proper pressure balance in combustion systems such as boilers and furnaces. When draft becomes too strong, these dampers automatically open to introduce air and reduce the pull on flue gases. This prevents excessive heat loss, improves combustion efficiency, and protects equipment from damage caused by unstable venting conditions.
How to Choose the Right Damper
Selecting the appropriate damper depends on the primary function required within your system:
- Backdraft dampers: Best for preventing reverse airflow and protecting ventilation and exhaust systems
- Pressure relief dampers: Ideal for controlling system pressure and protecting against overpressure conditions
- Barometric dampers: Used for regulating draft and improving efficiency in combustion systems
Kelair’s engineering team evaluates airflow direction, pressure requirements, temperature conditions, and system design to recommend the most effective solution. With adjustable counterweights, spring-assisted options, and custom configurations, each damper can be tailored to meet specific operating requirements and ensure long-term performance. As part of this process, documentation and support such as product registration can be provided to ensure traceability and proper system integration.
How Do Backdraft Dampers Work?
What is unique about these ventilation dampers is that they use one of the fundamental forces of nature – gravity. When air flows out of the backdraft ventilation damper, gravity is the means by which the damper closes, preventing air which has been contaminated from reentering the system.
Butterfly Dampers
Butterfly dampers are among Kelair’s most economical and versatile solutions, designed for both flow control and low-leakage isolation. These dampers are commonly used in duct systems handling clean air, gas or light particulate and can also be engineered for corrosive or high-temperature environments. Typical specifications include:
- Sizes ranging from approximately 6″ to 144″
- Temperature capability up to ~1900°F
- Shutoff performance up to ~99%+ depending on seal type
Butterfly dampers are ideal for applications requiring compact design, quick actuation and consistent performance across temperature swings.
Industrial Ducting
Kelair's custom-designed industrial ductwork is used in various applications, including pneumatic conveying, air pollution control, and industrial ventilation systems.
Isolation Valves
Isolation valves provide positive shutoff in air and gas handling systems, especially in hazardous or high-temperature environments. These components are typically installed at branch points or system junctions to isolate sections for maintenance, inspection or emergency shutdown.
Compared to dampers, isolation valves are more commonly used in piping systems but often work alongside dampers to provide complete system control and redundancy.
Butterfly Valves
Butterfly valves serve as flow control elements within piping and duct systems, regulating liquids, gases or particulates. These valves are often used in conjunction with industrial dampers to fine-tune process control. Available in multiple materials and configurations, butterfly valves are suitable for both low- and high-temperature applications and provide reliable, repeatable modulation.
Louver Dampers
Louver dampers (multi-vane dampers) are designed for precise airflow modulation in large duct systems. Their multiple blade design allows for accurate control of air or gas distribution while maintaining relatively low pressure drop.
Typical specifications include:
- Sizes from 14″ to 132″
- Temperature capability up to ~2100°F (with refractory options)
- Pressure up to 2 PSI and 4000 FPM
- Shutoff up to ~99% depending on seals
Louver dampers are commonly used in power generation, fan inlet control, metal processing and air pollution control systems.
Slide Gate / Guillotine Dampers
Slide gate (guillotine) dampers are designed for complete isolation and can achieve near-zero leakage. These dampers use a sliding blade mechanism that cuts through airflow and particulates, making them ideal for abrasive or particulate-heavy environments.
Typical features include:
- Sizes from 4″ to 96″
- Heavy-duty construction for high-temperature and corrosive conditions
- Minimal moving parts for reduced maintenance
These dampers are best suited for dust collection, mining and bulk material handling systems where isolation is critical.
Diverter & Tee Dampers
Diverter and tee dampers are used to redirect airflow between two or more outlets. These dampers are widely used in incineration systems and thermal oxidizers, where process air must be routed between operational paths or bypassed entirely.
They are available in round, square or rectangular configurations and can be designed for modulating or full shutoff service depending on the application.
Refractory Dampers
Refractory dampers are engineered for extreme heat and can withstand temperatures up to 2100°F.
These dampers are commonly used in:
- Kilns and furnaces
- Waste incineration systems
- Thermal oxidizers
Refractory lining reduces heat loss, protects structural components and improves durability in corrosive or high-particulate environments.
Inlet Vane Dampers
Inlet vane dampers regulate airflow entering fans and blowers to optimize performance and reduce energy consumption. By controlling airflow at the inlet, these dampers can significantly reduce horsepower requirements compared to outlet control methods.
They are widely used in HVAC and industrial ventilation systems where energy efficiency and precise airflow control are priorities and can also function as zone dampers in large-scale airflow systems.
Backdraft Dampers
Backdraft dampers are designed to allow airflow in one direction while preventing reverse flow. These dampers automatically open when airflow is present and close when flow stops or reverses.
Draft dampers are commonly used in ventilation systems to:
- Protect equipment
- Maintain system efficiency
- Prevent contamination or backflow
Stack Cap Dampers
Stack cap dampers isolate exhaust stack openings during system shutdown. These dampers prevent foreign material from entering the system, reduce heat loss and minimize the stack effect caused by temperature differences.
They are especially useful in high-temperature exhaust systems where maintaining system integrity and efficiency is critical.
