Zhang Huang fan, Roots fan, let me tell you how to choose Roots fan: Choosing Roots fan mainly depends on flow rate, pressure head, and meets other requirements such as installation and noise. Usually, the first choice is the form, such as centrifugal or axial flow. When choosing a new model, it mainly depends on factors such as flow rate, pressure head, whether to cut blades, and the size of the motor. ***Afterwards, meet other requirements such as noise. Firstly, it is necessary to analyze the requirements of the process for air supply: whether it is constant flow supply or constant pressure supply, how strict the process is with these parameters, and the severity of the consequences once these parameters are compromised. Roots blower belongs to constant flow fan, and the main parameter of operation is air volume. The output pressure varies with changes in pipeline and load, and the air volume changes very little. Centrifugal fans belong to constant pressure fans, and the main working parameter is air pressure. The output air volume varies with changes in the pipeline and load, and the air pressure does not change significantly. When these parameters are affected by * * * and the consequences are severe, you need to take auxiliary measures such as adding stabilizing valves, discharge valves, alarm devices, and automatic parking devices. Generally, large sewage treatment plants choose centrifugation, which has a high single unit air volume and high efficiency. Of course, * * * is also relatively large; Generally, small sewage treatment plants choose Roots, which has lower air volume and efficiency per unit, and is relatively small. It depends on the process. If it is CAST or SBR, using a Roots blower with variable frequency under variable water level is energy-saving. If the water level is constant in the A/O process, using a centrifugal blower is more efficient because the centrifuge can only adjust the flow rate through variable frequency, not the pressure. The Roots blower can adjust both the flow rate and pressure through variable frequency So it depends on the process, and of course, it also depends on the funding. Centrifuges are more expensive than Roots blowers Fans with an air volume of around 40m3/min are considered small fans, and Roots fans should be sufficient. Centrifuges with an air volume of over 100m3/min can demonstrate their energy consumption advantages. Roots fans are more practical in terms of price and energy consumption for small flow rates The flow rate, wind pressure, and power of Roots blowers are completely different from centrifugal blowers. The flow rate of blowers generally does not change much, while the pressure changes significantly. When the pressure increases, the shaft power increases; As the pressure increases, the shaft power of centrifugal fans decreases. ***It is not possible to reduce the air volume and pressure by adjusting the valve. Instead, a vent can be installed to regulate the air volume in the aeration tank. Why is it not possible to reduce air volume and pressure by adjusting the valve? It can cause excessive temperature rise of the fan motor, resulting in motor burnout. You can consult the fan manufacturer. Generally, a vent valve is installed to release unused air. If the valves are adjusted to a smaller size, it will cause excessive temperature rise of the fan motor, resulting in motor burnout.