Introduction and Technical Structure
In the design and execution of rectangular ductwork networks, one of the fundamental needs is changing the duct cross-section dimensions to adapt to equipment, diffusers, or spatial limitations. Kian Fan Industrial Production Group, by producing standard transitions for the rectangular duct system, provides an engineering and precise solution for managing size changes in the airflow path. The structure of these transitions is completely similar to the main ducts and is made of high-quality galvanized sheets.
The production process of transitions is carried out fully mechanically; after 3D modeling and precise cutting of the sheet by plasma machines, the bending stages are performed to create gentle or steep angles (depending on the type of transition). The edges of the sheet are connected to each other using the Pittsburgh seam, which creates a strong and integral connection. To increase strength and prevent deformation of the transition due to air pressure, transverse reinforcing beads are created on the body surface. If necessary for high pressures, additional reinforcing rods can also be used.

Connection System and Features
The connection of transitions to other components of the rectangular duct system, like the main ducts, is done using TDC (Transverse Duct Connector) flanges. This connection method includes flange profiles, corners, and cleats which accommodate the duct surface in a sliding manner. To guarantee complete sealing and prevent air leakage at the connection point, EPDM sealing tape is used between the flanges.
One of the important features of Kian Fan transitions is their aerodynamic design. A sudden change in duct size can cause excessive pressure drop and increased noise; however, the precise engineering of the transition wall angles at Kian Fan ensures that airflow passes from the small to the large cross-section (or vice versa) with minimal turbulence. This helps maintain system efficiency and reduce fan energy consumption.

Specialized Applications
Kian Fan rectangular transitions have widespread applications in all projects that use rectangular ducts. In office and commercial buildings, these transitions are used to connect the main large-sized duct to sub-branches with smaller sizes. In factories, transitions play a key role in adapting the outlet of ventilation equipment to the main ductwork network.
Also, in central HVAC systems, this product is used to change duct size to pass obstacles or enter spaces with low ceiling heights. Transitions are also essential for connecting rectangular ducts to devices such as Air Handling Units (AHUs) and centrifugal fans which have different opening dimensions.

Conclusion
The transitions of Kian Fan Industrial Production Group, relying on precise machine production, standard TDC connections, and aerodynamic design, are a reliable solution for changing dimensions in rectangular duct systems. Choosing this product guarantees design flexibility, preservation of air pressure, and increased ventilation system efficiency.