The 4-73 series fan is a common centrifugal ventilation fan, suitable for ventilation and air exchange in industrial and civil buildings. Its impeller is composed of 12 backward tilting airfoil blades, etc., with high efficiency and low noise. The casing is in the shape of a snail shell, and the air inlet is in a converging streamlined shape. There are multiple transmission modes and rotation directions, with stable and reliable performance, which can provide stable air volume and pressure for the system under different working conditions. It is a commonly used equipment in the field of ventilation.