1. The entire centrifugal fan unit should be placed directly on the foundation and leveled using paired wedge shims.
2. For centrifugal fans assembled on-site, the machined surfaces of the base should be properly protected from rust and damage. When placing the base on the foundation, paired wedge shims should be used for leveling.
3. The bearing housing and base should be tightly fitted. The longitudinal levelness should not exceed 0.2/1000, measured with a level on the main shaft. The lateral levelness should not exceed 0.3/1000, measured with a level on the horizontal center plane of the bearing housing.
4. Before scraping the bearing bushes, the rotor axis should be aligned with the casing axis. Simultaneously, adjust the clearance between the impeller and the air inlet, and the clearance between the main shaft and the shaft hole on the rear side plate of the casing, to ensure they meet the specifications in the equipment technical documents.
5. During the assembly of the main shaft and bearing bushes, inspection should be carried out according to the specifications in the equipment technical documents.
6. An interference fit of 0.03–0.04 mm should be maintained between the bearing cap and the bearing bush (measure the outer diameter of the bearing bush and the inner diameter of the bearing housing).
7. During fan casing assembly, the casing position should be aligned using the rotor shaft centerline as a reference. The axial and radial clearances between the impeller inlet and the casing inlet should be quickly adjusted to the range specified in the equipment technical documents. Simultaneously, check that the anchor bolts are tight. If the equipment technical documents do not specify the clearance values, the axial clearance should generally be 1/100 of the impeller outer diameter, and the radial clearance should be evenly distributed, with a value of 1.5/1000–3/1000 of the impeller outer diameter (take the larger value for smaller outer diameters). During adjustment, strive for smaller clearance values to improve fan efficiency.
8. During fan alignment, the misalignment between the fan shaft and the motor shaft should be: radial displacement should not exceed 0.05 mm, and tilt should not exceed 0.2/1000.
9. For centrifugal fans assembled with rolling bearings, the misalignment of the bearing holes on the two bearing brackets can be corrected by checking for smooth rotation after the rotor is installed.
