Volume Control Dampers
BDD Series
Standard Model: BDD
Frame: Galvanized Steel Sheet
Blade: Aluminium Sheet
Blade Operation: Parallel
COSMOS Linear Grilles and Registers covers a wide range for supply and return air distribution of HVAC systems and are suitable for ceiling, floor, sill and sidewall applications. They are selected for their pleasing continuous, line, architectural appearance and are designed for ventilation outlets and many other applications.
Product Description
COSMOS Gravity Dampers have been specifically designed for use in Air-conditioning and Ventilation system, these dampers are air operated and are used for air intake and exhaust, and are also used for pressure relief. Gravity Dampers can either be operated by gravity (where pressure or velocity opens and closes the damper) or be motorized to open and close when required. Backdraft dampers are designed for applications where air should only flow in one direction. These dampers always start in the fully closed position. Once air flows in the intended direction, it pushes the blades of the damper into the open position. As soon as airflow stops, the blades of the damper immediately fall to the closed position. If air flows in the opposite or wrong direction, then the blades will stay closed. This design ensures that air only goes in one direction and that airflow will not pass back through the other way. These dampers are composed of a set of horizontally mounted blades, they are normally closed and are free to rotate about the horizontal axis. The blades are manufactured from light weight aluminum sheets. Frame is manufactured from high quality aluminum as well as from galvanized steel.
Backdraft Damper
Backdraft dampers allow airflow in one direction and prevent reverse airflow for use in exhaust or intake HVAC systems. Backdraft dampers can either be operated by gravity (where pressure or velocity opens and closes the damper) or motorized to open and close when required. Backdraft dampers are used in ventilation systems to allow airflow in one direction and prevent airflow in the opposite direction.
The dampers are opened by air pressure differential and closed by gravity. They are rated for velocities up to 1500 fpm (7 m/s) and pressures up to 2 in. wg (0.5 k Pa). Damper selection begins by determine the damper construction required based on system velocity and static pressure. While selecting the correct damper for our application, we need to know following
Damper selection begins by determine the damper construction required based on system velocity and static pressure. While selecting the correct damper for our application, we need to know following
● System velocity and back pressure requirements.
● Mounting orientation and airflow direction.
● Mounting configuration (Inserted into duct / opening or flange mount )
● Damper operation ( gravity or motorized )
● Start-open pressure
Operating Principle
Non-return damper will allow one-way airflow in the ductwork. This feature is based on imbalanced blades. When the pressure in the ductwork drops below minimum opening force required, the blades close and seal the duct to prevent backflow. The minimum opening force can be adjusted with weights. Minimum opening pressure 30 Pa.
Features / Advantages
● The casing frame is fully sealed robust and rigid assembly formed out of best quality aluminum sheets / galvanized sheet steel of 1.2 mm thickness.
● Fully sealed low leakage blades are formed out of high quality light weight aluminum sheets of 1.0 mm thickness.
● The bearings are made of PVC / Nylon to give smooth and rattlefree operation.
● The blades are fitted with galvanized steel connecting spindle to main casing / frame for rigid and strong construction for rattlefree and smooth operation due to variable air pressure.
● A galvanized / aluminum angle is fitted internally to main frame to avoid over movement of blades.