Centrifugal fan is essentially a variable flow and cons […]
Centrifugal fan is essentially a variable flow and constant pressure device. When the speed is constant, the theoretical pressure-flow curve of the centrifugal fan should be a straight line. Due to internal losses, the actual characteristic curve is curved. The pressure generated in the AC Centrifugal Fans is greatly affected by changes in the temperature or density of the intake air. For a given intake air volume, the highest intake air temperature (lowest air density) produces the lowest pressure. For a given pressure and flow characteristic curve, there is a power and flow characteristic curve. When the blower runs at a constant speed When, for a given flow rate, the required power increases as the intake air temperature decreases.
1. The installation of the centrifugal fan unit should be directly placed on the foundation and leveled with pairs of inclined shim irons.
2. For centrifugal fans assembled on site, the cutting surface on the base should be properly protected, and there should be no rust or manipulation. When the base is placed on the foundation, it should be leveled with a pair of inclined shim irons.
3. The bearing seat and the base should be tightly connected, the longitudinal unlevelness should not exceed 0.2/1000, use a spirit level to measure on the main shaft, and the horizontal unlevel bottom should not exceed 0.3/1000, and use a spirit level on the horizontal midpoint of the bearing seat measuring.
4. Before the bearing bush is shaving, the rotor axis line and the casing axis line should be calibrated. At the same time, adjust the gap between the impeller and the air inlet and the gap between the main shaft and the shaft hole on the rear side of the casing to make it consistent with the equipment technology Document regulations.
5. When the main shaft and the bearing bush are assembled, they should be inspected according to the equipment technical documents. The interference between the bearing cap and the bearing shell should be 0.03～0.04mm (measure the outer diameter of the bearing shell and the inner diameter of the bearing seat).
6. When assembling the fan casing, the position of the casing should be aligned based on the rotor axis line and the axial and radial gaps between the inlet of the impeller and the inlet of the casing should be at a high speed to the range specified in the equipment technical file At the same time, check whether the anchor bolts are tight. If the gap value is not specified in the equipment technical documents, the general axial gap should be 1/100 of the outer diameter of the impeller, and the radial gap should be evenly distributed, and its value should be 1.5/1000～3/1000 of the outer diameter of the impeller. The smaller diameter takes the larger value). When adjusting, try to make the gap smaller to improve the efficiency of the fan.
7. When the fan is aligned, the difference between the fan shaft and the motor shaft: the radial positioning shift should not exceed 0.05 mm, and the tilt should not exceed 0.2/1000.
8. For centrifugal fans assembled with rolling bearings, the bearing holes on the two bearing frames have different axial degrees. After the rotor is installed, it is subject to flexible rotation.