Technical Requirements for Installing Backward-Curved Centrifugal Fans

Technical Requirements for Installing Backward-Curved Centrifugal Fans

The installation and adjustment of backward-curved centrifugal fans vary in scope and degree depending on the precision requirements, drive mode, speed, and power of each specific model. It is therefore crucial to configure and position these fans according to their individual specifications. Clean the surface of the foundation concrete and verify its levelness. Should it not meet specifications, uneven areas may be levelled. Using the backward-curved centrifugal fan as the foundation, insert shims between the fan base and the foundation surface, ensuring mortar flow during drying. Adjust the level using spacers to achieve complete horizontal alignment of the fan base. For installing standard backward-curved centrifugal fans, prepare several rectangular shims (steel plates) of varying thicknesses for layered adjustment. When installing critical backward-curved centrifugal fans requiring high precision, employ both vertical and horizontal shims for adjustment. Fans driven via couplings may be verified through the coupling itself; after level adjustment, proceed with welding and securing. Insert the anchor bolts through the buffer plates on both sides, utilising the adjustment bolts during levelling. The anchor bolt holes in the base must be perfectly perpendicular to the square holes in the anchor bolts. Any gaps between the anchor bolt holes and the foundation concrete must be filled with sufficient mortar to ensure structural integrity. When installing critical backward-curved centrifugal fans or high-precision backward-curved centrifugal fans, inject mortar into the anchor bolt holes. After the mortar has fully cured, proceed with horizontal adjustment. Once installation accuracy meets requirements, inject mortar into the gap between the foundation and the foundation concrete. 6) After the mortar has fully cured, tighten the nuts on the anchor bolts. Excavation management is critical throughout the backward-curved centrifugal fan installation process. This not only affects the space between the foundation and foundation concrete but also significantly impacts load transfer and mechanical rigidity of the fan. Therefore, during construction, particular attention must be paid to soil shrinkage and damage, employing appropriate construction methods. Generally, for large fans, the chassis and base are separate components. For bulk units, the casing is divided into several sections. During installation, first mount the backward-curved centrifugal fan base and bearing seat using the aforementioned method. Subsequently, assemble the casing, rotor, and upper cover while adjusting the stator-rotor clearance. Prior to assembly, verify that all mating surfaces are free from burrs, curled edges, or deformation. During assembly, take care to maintain the cleanliness of ground surfaces to prevent damage. When assembling the casing, avoid contact between the casing and the rotor, and do not impose additional loads on the rotor. To minimise the transmission of vibration forces, backward-curved centrifugal fans are often mounted on vibration dampers due to inadequate foundation design. The dampers should be positioned around the fan's centre of gravity to ensure equal compression across all dampers. This installation method reduces vibration transmission to the foundation but increases the fan's own vibration. Therefore, flexible connectors made of canvas or rubber must be used when connecting the inlet and outlet of the backward-curved centrifugal fan to ductwork. Within buildings, backward-curved centrifugal fans are occasionally suspended for installation. Except for very small units mountable on lifting eye bolt frames, welded frames integrated with ceiling foundations should be employed wherever practicable.