How to deal with the sealing at the shaft hole of the casing of centrifugal induced draft fan

- Feb 26, 2019-

Because of the lack of sealing requirements, the centrifugal induced draft fan has not been sealed at its casing and transmission shaft in the design and manufacture process, but it will not lead to gas leakage fault of the centrifugal induced draft fan, because the pressure at this position is negative pressure.


But after the use and related modification, the resistance and medium in the centrifugal fan will change. In order to prevent gas leakage in operation, it is necessary to increase the seal at the shaft hole of the casing of the centrifugal fan.


There are two main ways to install the seal. One is to dismantle the casing of the centrifugal induced draft fan, remove the impeller, move the transmission group, and then install the new packing seal or mechanical seal. The advantage of this method is that the sealing type can be selected and the installation specification is standardized, but the workload is relatively large and it will take more time.

Another one is completed without any disassembly of the centrifugal induced draft fan. It only needs to add a simple packing seal, but the key lies in the packing seal, which is composed of a filler, two pressing parts, two four semi-circular workpieces and so on.


When installing, the two workpieces marked with the organic shell type should be sleeved on the axle, and the groove is welded to a ring in the direction of the bearing box; then the two semi-circular workpieces with the unlabeled case type are also put on the transmission shaft, in the same way, the groove is welded to a ring in the direction of the housing. In this way, the transmission shaft passes through two rings and the grooves are opposite.


Next, weld the rings marked with organic shell, but pay attention to the inner circle of the rings is equal to the clearance of the transmission shaft; at the same time, weld the bolt hexagonal heads of the two pressing parts on the casing separately, so that one end of the pressing parts can be pressed on the rings; in addition, cut a piece of disc root and wrap it in the groove of the rings; fasten the nut of the pressing parts so that one end of the rings can be pressed and sealed safely. It was installed successfully.


Although seemingly more complex, but this installation only requires pre-processing of the workpiece, the later workload is actually very small, generally in the centrifugal induced draft fan with low sealing requirements can use this sealing form.