Additional specifications and description
The Constant Air Volume damper (CAV), also known as Constant Volume Regulator (CVR) is designed to be used with regular round or spiro ducts and comes with male-male spigots for easy press-fit installation. It maintains precise air volume metering, with a deviation of up to 10%, in a wide range of operating conditions. The operating mechanism uses an asymmetrical, angled control surface that is sensitive even to minute pressure differences, and offers a good control response with relatively low airflow rates. The sturdy Sendzimir galvanised steel construction and the automatic self-regulating mechanism with a calibrated counterweight make it suitable for both horizontal and vertical installation in supply or exhaust ducts.
Constant Air Volume dampers or CAV dampers are used in Constant Air Volume HVAC systems. This type of ventilation system is most commonly deployed in large interior spaces such as warehouses, atriums, auditoriums and theatres or multi-storey buildings. As the systems have a complex ductwork network, constant air volume dampers function to automatically control the distribution of air. Their purpose is to maintain a predetermined, constant volume of air flowing through them, despite any fluctuations in the air pressure in the ducts. The goal is to achieve a uniform airflow through all supply or exhaust vents, thus improving the comfort inside the building. This is very important in colder climates to combat the so-called thermal stacking effect which can cause hot air to be pushed out of the top of the building while cold air is sucked in on the lower floors.
Construction and installation method:
This round CAV damper is designed to be mounted in between two standard circular or spiro ducts and functions in either a horizontal or vertical orientation, both in supply and return ducts. Its housing is constructed out of Sendzimir galvanised steel that has been laser welded, ensuring a smooth internal surface that does not impede airflow while resisting dust and dirt buildup. The male-male spigots are equipped with EPDM rubber gaskets that help achieve an airtightness class D according to EN 12237, without the need for additional sealant. The product is corrosion-resistant and can withstand mildly corrosive vapours/solvents.
According to EN 12097, the damper should be installed in a manner that allows access to it and the control mechanism. When installed in a vertical duct run, it is recommended to fix it in place to avoid the damper moving due to vibrations/gravity. When installing the damper after a branch piece or a bend, it is recommended to add a duct between the CAV damper and the ventilation piece. The duct should be at least 2,5 times as long as the diameter of the damper. The working mechanism of the VRK damper functions without the need for external power or control - it only has to be set at the desired volume during the installation and will continue to operate maintenance-free.
While the automatic control mechanism is precise, unfavourable operating conditions can cause deviations from the desired air volume. The recommended mean airspeed in the ductwork should be at least 4,5 m/s and no less than 2,7 m/s. For the control mechanism to operate accurately, when mounted in a horizontal orientation, the airspeed should be at least 4 m/s. Lower than recommended airflow speeds, pressures exceeding 1000 Pa, or dust/dirt accumulation will negatively impact the accurate operation of the CAV damper.
Constant Air Volume dampers from Aerotechnik E. Siegwart GmbH comply with all applicable industry standards and are certified for use in commercial buildings and hospitals.
Note that the final airtightness of the ventilation system depends on several factors, including the installation method.