Common fault analysis and maintenance of multiple-stage centrifugal pump (TWO)

1, Impeller and impeller ring
The impeller was damaged because of cavitations or suction of solid substance, metallic impurity and so on. Impeller rings’ abrasion (sealing ring) are generally because of inappropriate installation or loose of cap nut. We should replace the impeller if the ring is severely worn out, if not we can just repair it.
2, Balancing device
Too much wear with balance disc and balance ring, (over 2mm) or scraggly in surface, add a 3mm PTFE gasket at the seaming surface. Thus the scraggly surface was filled and the material is also neither too hard nor too soft. If it over wear severely, the balance disc and balance ring should be replaced in time.
3, Mechanical seal
There is an end face perpendicular to spin axis, under the function of fluid pressure and external elasticity, with auxiliary seal, it can keep fit and relative slip with the other end, thus prevent fluid leakage. The proportion of mechanical sealing leakage takes over 50% of the whole pump set leakage. The running condition of mechanical sealing will directly affect the pump set performance. The pump rotor axial movement will be severely, the magnitude of interference of auxiliary seal and axial increase, rotating ring cannot move easily because of leakage. When pump is working, the rotating ring and stationary ring cannot fully compensation displacement. When assembling mechanical sealing, the axial movement should be less than 0.1mm; auxiliary seal and interference of shaft should be in a fair distance. It should not only guarantee the radial seal but also guarantee the easy move of rotating ring. (The rotating ring can bounce back automatically after pressed to the spring.)

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