Common Mistakes in the Maintenance of Small High-Pressure Centrifugal Fans

Common Mistakes in the Maintenance of Small High-Pressure Centrifugal Fans

1. When replacing the end covers (8 in total) of the centrifugal bearings on a small high-pressure centrifugal fan, the fixed end cover and the free end cover are not installed correctly. This may be due to an attempt to accommodate thermal expansion of the fan shaft in high-temperature environments. Manufacturers design the rear non-locating bearing to require precise positioning of the locating bearing. Since the free bearing is installed in a way that allows for movement, it restricts the shaft’s free expansion and contraction. This could potentially lead to equipment failure. In this case, install the upper and lower flanges of the bearing end cap with a short overlap. This ensures that the other end caps are properly aligned and not affected by the thickness of the seal rings. 2. When adjusting small high-pressure centrifugal fan equipment, tighten or loosen the anchor bolts to “meet” the relevant precision requirements, or adjust the shims; however, when tightening or loosening the anchor bolts, add shims between the motor or fluid coupling and the base plate. Anchoring bolts may result in uneven pre-tightening forces across the bolts, and excessive stress during operation can cause individual anchoring bolts to fail easily. Additionally, if retightening is required during future operation and maintenance of the small high-pressure centrifugal fan, the adjusted installation dimensions may be compromised. The motor, base plate, fluid coupling, and foundation must be considered as a single unit. Shims should only be added between the base plate and the foundation. In this case, shims should be used to adjust the installation dimensions between the base plate and the foundation. When tightening the bolts around the feet, the force applied to the bolts will generally be uniform. 3. The bearings of small high-pressure centrifugal fans are lubricated by an oil pump. Under normal operating conditions, the bearings do not leak oil; therefore, if the oil pump fails, neglecting maintenance to compensate for installation difficulties is unwise. In such cases, the oil reservoir serves to draw oil from the bearing housing and supply a certain amount of oil during unexpected power outages or short-term failures of the oil station. To ensure the bearings continue to rotate without damage, the oil reservoir is essential and must not be omitted.