（2） Precautions for normal operation of fan 1. If the flow is found to be too large, which does not meet the operating requirements, or less flow is required in a short time, the throttling device can be used to adjust to meet the operating requirements. 2. The sensitivity of thermometer and oil pointer shall be checked regularly. 3. In case of any abnormal phenomenon during the start-up, shutdown or operation of the fan, it shall be checked in time. 4. For minor faults found in the inspection, find out the causes in time and try to eliminate or deal with them. If minor faults cannot be eliminated or major faults are found, repair them immediately. 5. In addition to replacing the lubricating oil during each maintenance, the lubricating oil shall also be replaced regularly. Observe the oil level at ordinary times and replenish lubricating oil in time.

9. Since the flow, total pressure, main shaft speed and shaft power of the fan have a fixed relationship, the main shaft speed should not be changed when the motor capacity does not change. If the main shaft speed increases, the motor may be burned due to overload. The motor power used by the fan refers to the power not required when the air inlet and outlet are fully open in terms of mechanical losses and due reserves under a specific mine. If the outlet or inlet of the fan is not connected to the pipeline or is idle without external resistance, the motor may also be burned out. For safety, a valve shall be added to the outlet or inlet pipeline of the fan, and it shall be closed when starting the motor. After turning, the valve shall be slowly opened until the specified working condition is reached, and attention shall be paid to whether the current of the motor exceeds the specified value. High power motors must be started in proper ways, such as voltage reduction, frequency conversion, etc.

（1） Centrifugal fan company The operating environment should always be kept clean, the fan surface should be kept clean, and the air inlet and outlet should be free of sundries. Regularly remove dust and other sundries in the fan and pipe. （2） customized Centrifugal fan It can only be operated when the fan is completely normal. At the same time, it is necessary to maintain sufficient capacity of power supply facilities and stable voltage. Open phase operation is strictly prohibited. The power supply lines must be dedicated lines, and temporary lines should not be used for long-term power supply. (3) In case of abnormal sound, serious heating of motor, electrification of shell, tripping of switch, failure to start and other phenomena of fan during operation, the fan shall be stopped immediately for inspection. To ensure safety, maintenance is not allowed during the operation of the fan. After the maintenance, the test run shall be carried out for about five minutes, and the machine shall be restarted after confirming that there is no abnormal phenomenon. （4） Henan Centrifugal fan company Replenish or replace lubricating grease for bearings irregularly according to the service environmental conditions (it is not necessary to replace lubricating grease for motor enclosed bearings within the service life). To ensure good lubrication of the fan during operation, the number of times of oiling shall not be less than 1000 hours/time. For enclosed bearings and motor bearings, fill 2/3 of the inner and outer rings of bearings with ZL-3 lithium based lubricating grease. It is strictly prohibited to run without oil. (5) The fan shall be stored in a dry environment to prevent the motor from moisture. Rain proof measures shall be taken when the fan is stored in the open air. The fan shall be prevented from collision during storage and handling to avoid damage to the fan.

The selection of fans Product performance and fan performance listed in the selection table are based on the performance of delivering air under standard conditions. Therefore, when the use condition is non-standard, the H4-72-12 centrifugal fan must convert the use performance into the performance under standard conditions according to the relationship in the table above, and then select according to the performance and selection table. （3） Treatment of excessive or insufficient flow During use, excessive or insufficient flow often occurs. There are many reasons for this phenomenon. If the flow is high and low during use, it is mainly because the resistance in the pipe network is high and low, or the fan works in a non working area. If it is gradually reduced after a long time during use, it is mainly due to pipe network blockage. After the fan is newly installed, the flow is too large or insufficient during the formal operation. The main reasons for this phenomenon are as follows: 1. The actual value of pipe network resistance is too different from the calculated value. In the general pipe network characteristic equation, H=KQ2, if the actual value K of K-resistance coefficient is less than the calculated value K, the flow will increase; If the actual value K is greater than the calculated value K, the flow decreases. See (b) below.

Centrifugal fan company Forecast from the characteristics of fan demand. customized Centrifugal fan For small and medium-sized fans with large usage and wide range, the product structure and manufacturing process are relatively simple, and the cost is also low. Users mainly pursue high efficiency, low noise, long life, and low price. The other is capital and technology intensive. The product structure is complex, the manufacturing cycle is long, and the completeness and systematicness are also strong. Moreover, it operates under high pressure, high temperature and high speed conditions, and some even operate under severe conditions. Users have different requirements for this type of fan. For turbine blowers, compressors and large ventilators, users mainly pursue high quality, high reliability, smooth operation and long cycle