The issue of the disassembly direction for centrifugal pump impellers
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Our company has SJ-type centrifugal pumps, whose impellers are of the closed-type design. After the mechanical seal started leaking, we tried to remove the impeller and found that it couldn’t be taken off – the impeller had threads. It turned out later that we were removing it in the wrong direction; by following our usual method and removing the impeller from the opposite direction, it only became tighter as we continued to remove it. Later, we removed it by rotating the pump impeller’s fluid, and it was successfully taken off. What is the reason for this? Under normal circumstances, it should be removed counterclockwise – why is it being removed clockwise? Solve
Installing the impeller in this way ensures that it becomes tighter as it rotates during normal operation, preventing it from loosening.
The shaft ends of rotating equipment are machined with reverse threads, primarily to prevent the loosening of threaded connections due to the rotation of the equipment. Anti-rotation nuts are used; these nuts lock up as the equipment rotates, so special attention must be paid to the direction of disassembly – it cannot be carried out in the usual manner.
In fact, as long as one knows the operating direction of the pump, it is possible to determine the rotation direction of the impeller as well as the direction in which the impeller can be removed.
When disassembling, make sure the direction of the impeller flow channels is consistent; it is generally in the opposite direction to the rotation direction of the pump
The specific method is similar to that used for installing and removing car tires, which ensures that the impeller does not become loose at high speeds
The rotation direction of the impeller is the direction in which it should be removed
The direction of removing the impeller must be opposite; this is to ensure that the bolts tighten as the impeller rotates, thereby preventing the impeller from coming loose
The impeller nut has an anti-rotation screw, which must be removed first