Centrifugal fans often coexist with the pipe network, which is commonly referred to as the fan system. The performance achieved by the fan when it operates alone is often changed after adding the pipe network. The system resistance is the most influential. Therefore, the pipe network system should be taken into consideration when designing the fan system. The following editors have sorted out the influence and adjustment methods of the resistance of the centrifugal fan system for your reference.
1) System resistance curve
Under a certain volume flow through a given centrifugal fan system, a corresponding pressure loss will occur, and this pressure loss is the system resistance. If the flow rate changes, this pressure loss will also change, usually the pressure loss is proportional to the square of the volume flow. The pressure loss corresponding to different volume flows is drawn on the chart, and the resistance curve of the system is obtained, and the system resistance curve is in a typical parabolic shape.
2) The influence of the resistance of the centrifugal fan system
1. The influence of large resistance
When the system resistance increases, such as closing the baffle door, blocking the filter screen, etc., the flow of the centrifugal fan will decrease and the pressure will increase. That is to say, when the system resistance curve is higher than the design value, it will lead to the actual centrifugal fan. The pressure is higher than the design value, and the actual flow rate of the fan is smaller than the design value. When the actual pressure of the fan is close to the ultimate pressure of the fan, the operation of the fan is unstable, and the fan will stall.
2. The influence of small resistance
Similarly, when the system resistance decreases, the flow of the fan will increase and the pressure will decrease, that is, when the system resistance curve is lower than the design value, the actual pressure of the fan will be lower than the design value, and the actual pressure of the fan will be lower than the design value. The flow rate is greater than the design value. In this case, the motor may be overloaded.
3) fan system resistance adjustment method
1. Adjustment of excessive resistance: Fully open the damper in the system to clean the blockage of the system and reduce the resistance; at the same time, check the air leakage of the system and open the adjustment baffle of the centrifugal fan.
2. Adjustment if the resistance is too small: Reduce the opening of the damper in the system, supply air to other applications, and close the adjusting baffle of the centrifugal fan at the same time.
