Causes of Mechanical Seal Leakage of Liquid Ring Vacuum Pump
2026/07/28 11:46
Daily maintenance is the foundation for stable operation of all industrial equipment. Any long-term lack of inspection will trigger various minor or serious malfunctions, and mechanical seal leakage is one of the most frequent failures of liquid ring vacuum pump.
Liquid ring vacuum pump, also called water ring vacuum pump, belongs to general industrial vacuum equipment widely used in chemical plants, pharmaceutical factories, power stations and coal mine gas extraction projects. The mechanical seal installed at both shaft ends is a vulnerable wearing part. Once leakage occurs, the system vacuum will drop sharply, circulating water will be wasted, and even adjacent electrical components will be corroded.
Most on-site maintenance personnel cannot systematically judge leakage sources. This article divides the whole content into five major modules, including fault root causes, secondary hidden factors, targeted repair schemes, standardized assembly specifications and long-term preventive maintenance, with detailed sub-items under each module for clear reading.
Continuous dripping will erode pump bearings and driving motors, shortening the service life of power components.Insufficient vacuum degree will reduce gas extraction efficiency and delay the whole production schedule.Frequent replacement of seal spare parts increases long-term operating costs of enterprises.
Mechanical seal separates the internal circulating water and external air of the pump cavity.Dynamic ring rotates synchronously with the main shaft, while static ring is fixed on the pump cover.The elastic spring provides pre-tightening force to keep the two sealing planes tightly fitted.
Three Primary Root Causes of Mechanical Seal Leakage
More than 70% of on-site leakage faults are directly caused by three typical structural damage and parameter mismatch problems.
Each fault has independent formation logic and on-site manifestation, which will be analyzed separately below.
Damaged Dynamic and Static Sealing Surfaces
Scratches, cracks and fragmentation on the matching plane are the top trigger of repeated leakage.Unbalanced shaft support during disassembly leads to shaft deflection and scratches the static ring surface.Solid sediment in unfiltered cooling water continuously polishes the sealing plane during long-time operation.Once the liquid isolation film between two rings is destroyed, persistent water seepage will appear during operation.
Exceeded Standard Cooling Water Pressure
The spring preload between dynamic and static rings is easy to be offset by excessive hydraulic pressure.The on-site test data of Lrac series liquid ring vacuum pump can fully verify this risk.When the cooling water valve opening exceeds two-thirds, reverse water pressure pushes the dynamic ring backward and compresses the spring.Joint investigation of maintenance team and seal manufacturers confirms this is a common on-site leakage cause.
Non-Standard Disassembly and Assembly Operations
Wrong placement of O-rings is a typical assembly error in actual overhaul work.The rubber O-ring should be embedded into the dedicated groove of dynamic ring base instead of outside the spring plate.Misplacement causes permanent spring deformation and loses axial sealing capacity.Scratching seal parts and uneven bolt tightening will also accelerate early seal failure.
Secondary Hidden Factors Inducing Slow Leakage
Apart from the three obvious main faults, many subtle neglected conditions will slowly damage the sealing structure after months of continuous operation
leading to invisible slow seepage that is hard to detect in daily patrol.
Aging of Auxiliary Sealing Rubber Parts
Long-term contact with water and industrial gas makes O-rings and gaskets hard and brittle.Aged rubber loses elasticity and cannot form a fully closed isolation gap.Even new mechanical seals will leak slightly if matched with aged rubber accessories.
Wear and Tear of Shaft Sleeve Surface
Long-term relative friction leaves uneven scratches on the surface of shaft sleeve.The smooth fit between O-ring and shaft sleeve is destroyed, resulting in slow water seepage.Serious shaft sleeve wear requires integral replacement together with the mechanical seal set.
Lack of Filter Device on Circulating Water Pipeline
Rust, mineral crystals and tiny impurities enter the seal chamber with cooling water.Micro-abrasion will form on the sealing plane day by day, gradually expanding leakage traces.This hidden damage accumulates slowly and is difficult to find in short-term inspection.
Structural Differences of Other Vacuum Equipment
Roots vacuum pump and screw vacuum pump adopt different mechanical seal designs.Enterprises equipped with multiple vacuum models need to formulate classified maintenance standards.Classified inspection rules can reduce the overall replacement frequency of sealing spare parts.
Complete Targeted Repair Solutions for All Leakage Faults
Corresponding standardized repair methods are formulated for every type of leakage fault summarized above.
All operations comply with industrial pump overhaul specifications, which can be directly followed by on-site maintenance staff.
Repair Measures for Scratched or Cracked Dynamic & Static Rings
Shallow surface scratches can be sent to manufacturers for precision grinding and flat calibration.Cracked or broken sealing rings must be replaced with a complete matching set.Auxiliary support brackets shall be used during disassembly to avoid shaft deflection.Soft protective film is required to wrap intact seal ends to prevent accidental scratch damage.
Cooling Water Pressure Adjustment Scheme
Install real-time pressure gauges and pressure regulating valves on cooling pipelines.Control the inlet valve opening within two-thirds under normal production.Set up bypass shunt pipelines if large cooling flow is needed.Regularly overhaul water supply pumps to eliminate sudden pressure surges.
Standard Assembly Operating Specifications
Fully clean shaft sleeves, sealing grooves and all accessories before installation.Place O-rings into designated grooves without twisting the spring assembly.Tighten gland bolts crosswise by torque wrench to ensure uniform pressure.Manually rotate the pump shaft to check smoothness before water leakage test.
Long-Term Preventive Maintenance System to Avoid Recurring Leakage
Simple one-time repair only solves temporary leakage problems.
Establishing a complete daily maintenance system can fundamentally reduce the failure rate of mechanical seals and extend the service life of spare parts.
Fixed Shift Daily Inspection Items
Operators need to check cooling water pressure value every shift.Observe the shaft end of mechanical seal for dripping or wet traces.Record abnormal pressure changes and slight seepage in equipment log.
Scheduled Overhaul Replacement Rules
Replace all aged rubber O-rings and gaskets during shutdown maintenance.Regularly check the wear degree of shaft sleeves and sealing planes.Install multi-stage filters on circulating water pipelines to intercept solid particles.
Customized Seal Material Matching Rules
Select silicon carbide dynamic and static rings for coal mine wear-resistant working conditions.Adopt fluororubber sealing accessories for corrosive chemical medium.Communicate production medium information with manufacturers before purchasing seals.
Professional Manufacturer Technical Support Channel
Send fault photos and operating parameters when encountering complex leakage.Obtain one-to-one troubleshooting guidance from liquid ring vacuum pump suppliers.Ask for complete performance curve data during equipment ordering.
Conclusion
Mechanical seal leakage of liquid ring vacuum pump is caused by multiple superimposed factors, including direct structural damage and long-term hidden wear. Starting from five major dimensions of fault overview, primary causes, secondary hidden risks, targeted repair plans and daily maintenance systems, this article sorts out complete judgment and operation logic.
Enterprises can formulate internal pump maintenance SOP according to the above content. Standardized inspection, disassembly and daily upkeep can effectively reduce seal failure frequency, cut spare part procurement cost and avoid unexpected production shutdown caused by water ring vacuum pump leakage.
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