Is it only multi-stage pumps that require shaft displacement measurement?
Thread Content
Is the cause of the axial displacement still the large pressure difference in the multi-stage pump, which leads to axial displacement?
A high pressure at the pump outlet generates an axial force in the direction of the low-pressure side. A balance drum or balance disk is needed to counteract this axial force, ensuring that the rotor and impeller remain centered within the pump
It is likely that abnormal processing conditions cause changes or increases in axial force. As for the claim of displacement, it only occurs when the bearing is damaged.
For some important pump systems, it is necessary to monitor the operating condition of the thrust bearings; therefore, an axis displacement sensor along with interlocks must be installed. After all, the axial force in multi-stage pumps is quite high, and if the balance tubes become blocked or broken, it is very likely that the thrust bearings will experience abnormal and rapid wear~~~
It is not only multi-stage pumps for which axial displacement needs to be monitored; ordinary single-stage centrifugal pumps also require the axial displacement to be kept within 0.5 mm, in order to prevent leaks from the mechanical seal as well as wear between the impeller and the pump casing； For shielded pumps, it is even more important to control the axial displacement properly, in order to prevent rubbing between the rotor and stator, as well as between the impeller flange and the pump casing
For the balance disc type, during installation and adjustment, it is necessary to limit the total amount of movement of the rotor, and then adjust the movement after assembly to ensure the correct operating position of the rotor. For bearing positioning, the balance drum clearance is ensured during installation. An increase in shaft displacement during operation indicates flow fluctuations and worn balance discs. In systems that use balance drums for bearing alignment, shaft displacement does not increase much, as excessive displacement would cause the bearings to fail