Rectangular ventilation butterfly valves, also known as rectangular dampers, come in two types: cast iron rectangular dampers and steel rectangular dampers. They are used in power plant boiler flue gas systems to regulate mass flow or directly interrupt mass flow, serving dual functions of adjustment and cutoff within the system.

The 74DD rectangular air damper conforms to the original 74 Code standard of the former Ministry of Power. Its blades are cast, ensuring no deformation or bending at high temperatures, thereby preventing malfunctions such as poor operation and insufficient driving force. The steel rectangular air damper is an improved version of the 74DD model. It is a new product designed and manufactured by our company based on foreign technology. Due to the 74DD cast damper's poor sealing, the bearing ends of the blades being difficult to align, and the excessive driving torque, the steel damper can be used as a substitute. The bearings of the steel damper are spherical universal joints, and the sealing elements are adjustable thin plates, which result in lower driving torque and higher sealing performance.

Rectangular ventilation butterfly valves are available in five types: single-axis, double-axis, triple-axis, quadruple-axis, and quintuple-axis. Specifications include 300.x400-20002400 and 66 types.

The rectangular ventilation butterfly valve can be horizontally or vertically mounted, with the medium temperature not exceeding 400 degrees Celsius.

The bearing neck of the main shaft of the rectangular ventilation butterfly valve is provided for the installation of the worm gear box. The wind door housing is equipped with a stop pin when the baffle is fully open.