Determining the Rotation Direction and Angle of Multi-Blade Low-Noise Centrifugal Fans and Their Series Connection

Determining the Rotation Direction and Angle of Multi-Blade Low-Noise Centrifugal Fans and Their Series Connection

Any type of multi-blade low-noise centrifugal fan, after proper calculation of parameters such as airflow and air pressure, can be used for ventilation, exhaust, cooling in environmental engineering, painting, cooling towers, construction sites, tunnels, or for induced draft ventilation in industrial boilers. To ensure quick and effective operation of multi-blade low-noise centrifugal fans, they must be installed correctly. The installation location and orientation of multi-blade low-noise centrifugal fans primarily depend on the environmental conditions of the installation site. The rotation direction of centrifugal fans is classified into two types: left-hand and right-hand, also known as clockwise and counterclockwise. When determining the direction, the reference point is the rear end of the motor. OK When facing the inlet of the multi-blade low-noise centrifugal fan, the fan blades rotate clockwise. In other words, they rotate to the left. When rotating counterclockwise, the fan rotates to the right. When facing the rear of the multi-blade low-noise centrifugal fan: if the fan motor and propeller rotate clockwise, the fan rotates to the right. If they rotate counterclockwise, the fan rotates to the left. Starting from the rear of the motor, the air outlet is at 0° relative to the ground, 90° vertically upward, and 180° parallel to the ground; other angles vary accordingly. In many industrial designs, due to certain constraints, only a single multi-blade low-noise centrifugal fan can be used; however, the fan is often too small to meet the required airflow and pressure specifications. In such cases, multiple multi-blade low-noise centrifugal fans are connected in series. Direct-discharge multi-blade low-noise centrifugal fans can increase air pressure. Two or more such fans are connected at the front and rear to convey gas into a duct. Typically, when connected in series, one is positioned before the equipment and the other after it. Installation If the two multi-blade low-noise centrifugal fans are identical, the total airflow of the system equals the airflow of each fan, and the pressure is the sum of the two. In this scenario, since the operating curves of the centrifugal units are identical, the static pressures overlap at the same flow rate. By connecting two low-noise multi-blade centrifugal fans in series, the system’s static pressure increases, provided each fan has sufficient capacity. This allows for the delivery of a greater volume of air into the ductwork.