One of the centrifugal pumps in our plant starts frequently; due to the level gauge interlock, this causes the impeller cover to become loose
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One of the centrifugal pumps in our factory starts frequently; due to the interlock mechanism based on the level gauge, this causes the impeller cover to loosen, eventually leading to damage to the impeller. The repair costs are high. What are some solutions?
As far as I understand, it’s only when it reverses that it loosens!
The caps are equipped with locking washers, and as mentioned on the second floor, they generally don’t loosen
Adjust the liquid level interlock control to widen the start and stop ranges; it is advisable to use an inverter – reducing the frequency at high levels and increasing it at low levels (to save energy)
Is it due to the high liquid level interlock activation code? First, identify the root cause and address the issue that leads to high liquid levels, in order to reduce the frequency of interlocks. Alternatively, through change management, discuss whether the threshold for triggering interlocks due to high liquid levels can be increased, thereby reducing such interlocks. Your description is not specific enough
A loose impeller nut means the impeller is rotating in the reverse direction. Given that you start the pump frequently, is an electric valve installed at the pump outlet? It is likely that the pump motor was enlarged to simplify things (taking maximum power into account), and there is only a check valve at the outlet. I recommend installing an electric valve at the pump outlet, as this valve can be controlled to open and close via DCS!
Agree with the comment on floor 4: use an inverter for control to prevent the motor from starting frequently.
Use a grinder to create a small notch in the back cap or to flatten one of its sides (the outer surface, without affecting its functionality), then make an aluminum pad. Once the back cap is secured in place, use a screwdriver to lift one side of the aluminum pad upward, which will prevent it from falling off. We have also encountered units that lack caps and rely on self-locking impellers; such pumps tend to fall off very easily. In those cases, we applied thread sealant imported from the United States, left it in place for one night, and when the pump was started the next day, it no longer fell off
Based on an analysis of your situation, it is likely that the check valve at the pump outlet is leaking, causing the pump to rotate in the reverse direction; moreover, the pump’s back cover is loose. It is recommended to repair or replace the check valve. It has happened here as well, but the pump outlet is equipped with a one-way stop valve.
It would be better to drill a screw hole in the axis of the pump shaft and the back cap, and install a lock screw.