1. Fan Maintenance Rules

1. Fans must be operated and serviced by designated personnel only.
2. Never run a fan that is faulty.
3. Clean dust from inside the fan regularly — especially dust and dirt on the impeller — to prevent corrosion and imbalance.
4. Always cut the power and stop the fan before any repair.
5. Check the thermometer and oil level gauge for sensitivity at regular intervals.
6. Replace the lubricating oil after every overhaul; under normal conditions replace it every 3–6 months.

2. Main Fan Faults and Their Causes

1. Violent vibration of the bearing housing
 1) The fan shaft and the motor shaft are not concentric, or the coupling is misaligned.
 2) The casing or air inlet rubs against the impeller.
 3) The foundation is not rigid enough.
 4) Impeller rivets are loose, or the impeller is deformed.
 5) The impeller shaft disc is loose on the shaft, or the coupling bolts are loose.
 6) Connecting bolts are loose between casing and bracket, bearing housing and bracket, or bearing housing cover and seat.
 7) The fan inlet and outlet ducts are poorly installed.
 8) The rotor is unbalanced, or the induced draft fan blades are worn.

2. Bearing temperature too high
 1) Violent vibration of the bearing housing.
 2) Poor-quality or deteriorated grease containing too much dust, sand or dirt.
 3) Bolts connecting the bearing housing cover and seat are too tight or too loose.
 4) The shaft and the rolling bearing are installed at an angle, so the front and rear bearings are not concentric.
 5) The rolling bearing is damaged.

3. Motor current too high, or temperature rise too high
 1) The inlet duct gate or throttle valve is not fully closed at start-up.
 2) The flow rate exceeds the specified value.
 3) The gas being conveyed is too dense or contains sticky substances.
 4) Motor input voltage is too low, or there is a single-phase power failure.
 5) The coupling is misaligned; the rubber ring is too tight or the clearance is uneven.
 6) Affected by violent vibration of the bearing housing.