A sudden water leak in a multistage centrifugal pump is really annoying, especially when you watch the water stain spread. Don't rush to disassemble the pump. First, figure out where the water is leaking from and why it’s leaking—only then can you take targeted measures. There are various reasons for water leakage, but common problems usually concentrate on several key parts.
Mechanical Seal Failure
This is the most common "culprit". Wear or cracking of the dynamic and static seal ring end faces, or aging, hardening, and scratches during installation of the O-ring, can all lead to seal failure. Poor water quality (containing particles or having strong corrosiveness) will accelerate wear.
Solutions: Shut down the pump to check the condition of the seal end faces, and replace the damaged dynamic/static seal rings or O-rings. Improve water quality or select more durable seal materials (such as silicon carbide and ceramics).
Loose or Worn Packing Seal
Old pumps or those used in specific working conditions adopt packing seals. If the packing gland is too loose, or the packing itself is severely worn or hardened, water will seep out.
Solutions: Tighten the packing gland bolts evenly and gradually (do not tighten them too tight at one time), or replace the packing with a new one. Note that an appropriate amount of dripping (a few drops per minute) should be maintained for lubrication.
Cracks or Blowholes in the Pump Body
Casting defects, long-term vibration, or water hammer impact may cause tiny cracks or blowholes in the pump body. When the pressure is high, water may leak in a jet shape.
Solutions: For minor cracks, try repairing them with special glue (for temporary emergency use). For severe cases, the pump body must be replaced. Ensure the installation foundation is stable to reduce vibration.
Leakage at Flange Connection Surfaces
At the connections of inlet/outlet flanges and middle-section flanges, loose bolts, aging and damaged gaskets, scratches, or debris on the sealing surfaces can all cause water leakage.
Solutions: Tighten the bolts evenly in a diagonal sequence. Replace aging or damaged gaskets (pay attention to selecting the correct type). Clean the sealing surfaces to ensure they are flat and free of impurities.
Wear of Balance Disk/Balance Drum
Multistage pumps rely on the balance mechanism to balance axial force. Severe wear of the balance disk and balance sleeve (or balance drum and bushing) will increase the gap, leading to an abnormal rise in the pressure of the balance chamber. As a result, water seeps out from the balance pipe or the seal of the balance mechanism.
Solutions: Check the gap between the balance disk (drum) and the balance sleeve (bushing). If the gap exceeds the standard, replace the worn parts. Check whether the balance pipe is unobstructed.
For water leakage in multistage centrifugal pumps, the three main causes are seal failure (mechanical seal/packing), connection leakage (flange/pump body), and wear of the balance mechanism. When dealing with the problem, the core steps are locating the leak point, analyzing the cause, and operating in a standardized manner. In daily use, paying attention to water quality management, conducting regular inspections and maintenance, and avoiding overpressure and overload operation can effectively reduce water leakage faults and extend the service life of the pump. When encountering complex problems, it is safer to contact professionals in a timely manner.
Do you need me to organize a bilingual comparison table of key terms for multistage centrifugal pump leakage maintenance to help you quickly find corresponding English expressions during actual operations?