The back valve is designed for shutting off air flow in rectangular air ducts and preventing air from moving backwards when the ventilation system is idle. The minimum air flow speed through the back valve’s cross-section must be at least 4 m/s. The valve is designed for operation at the temperature of 400 °C for 2 hours.
The valves are made of galvanized steel in inline design and have two connecting flanges. The gravity blades are attached on rotating axes. The design of the valve enables it to be used in a horizontal position with the blades facing up.
