Since centrifugal pumps are a common piece of fluid conveying equipment in the industry, their common faults typically involve mechanical structure problems, abnormal operation parameters, or external environmental impacts. The following lists the common faults of centrifugal pumps in three steps: fault phenomena, causes, and solutions.
Safety Risks Caused by Overpressure and the Self-adaptive Control System
Fault Phenomena
A centrifugal pump’s internal pressure may rise abnormally during operation due to several reasons, including obstruction of the outlet pipeline, improper valve operation, or abrupt changes in operating conditions. This can then result in anomalous occurrences such as increased mechanical vibration and driving motor overload. In extreme situations, it may present safety risks such as structural fracture of the pump body and failure of the sealing elements.
Solution by Longgang Pump Industry
The overpressure self-adaptive system of our centrifugal pumps dynamically adjusts the opening degree of the bypass through the pressure-controlled reflux device, achieving a dynamic balance regulation mechanism between flow and pressure. This effectively avoids overpressure and pump choking faults, protecting the safety of the pump and the motor. Verified by 3D simulation and a test bench (with a maximum pressure of approximately 30MPa), our system can ensure operational reliability under extreme working conditions.
Seal Failure and Leakage, and Advanced Sealing Technologies
Fault Phenomena
Centrifugal pumps using traditional packing seals, gland seals, or mechanical seal structures are prone to medium leakage due to wear of the sealing elements, material aging, or fluctuations in working condition parameters. Especially when conveying corrosive fluids or high-viscosity media, the probability of seal failure significantly increases, posing a risk of medium leakage polluting the environment and even triggering safety accidents.
Solution by Longgang Pump Industry
- Mechanical Sealing Technology: Our centrifugal pumps are equipped with a secondary impeller dynamic sealing system (achieving zero leakage of gas-liquid media and meeting the requirements of long-term continuous operation) and a full-working-condition adaptable skeleton oil seal. Through the coordinated action of multi-stage seals, the leakage defects of traditional seals are effectively eliminated.
- Thermal Expansion Seal Protector: The rotational supporting structure compensates for displacement (≤ 0.8mm) caused by pressure (or temperature) changes and buffers the axial force, extending the service life of the mechanical seal bearings from the conventional 12 months to 36 months, effectively reducing maintenance costs.
Vibration Issues and Multi-dimensional Technical Optimization
(I) Vibration Caused by Internal Backflow in the Pump Casing
Fault Mechanism
The pressure difference between the pump body’s discharge chamber and suction chamber causes liquid backflow. The impact of the suction liquid and the backflow liquid leads to vibration. Long-term operation may result in damage to the bearings and wear of the impeller.
Solution by Longgang Pump Industry
The flow channel design is optimized and validated by a high-precision test bench (meeting the accuracy standard of GB/T3216-1 level) based on 3D flow field analysis to identify areas of uneven pressure. The pressure is controlled in real-time to block the impact of the liquid flow, lowering the vibration amplitude and guaranteeing the operational stability of the pump set under complex conditions like cavitation tests and variable frequency working conditions.
(II) Vibration Caused by an Improper Distance between the Impeller and the Casing Throat
Fault Mechanism
Hydrodynamic characteristics will be changed when the distance between the maximum outer diameter of the impeller and the casing throat (the throat of the pump body) is not reasonably designed, leading to an increase in the hydraulic exciting force and causing vibration of the pump body.
Solution by Longgang Pump Industry
Relying on rotor dynamics technology, a shaft system vibration model is established. Through data collection of multiple models, the critical diameter ratio is determined. The impeller semi-ring positioning (axial clearance to prevent thermal deformation) and balance disc parameters are optimized to suppress vibration from both the structural and flow field dimensions.
Shaft System Deformation and Durability Issues, and Structural Design
Fault Phenomena
In traditional centrifugal pumps, under conditions of drastic temperature changes or high loads, the shaft system components are prone to deformation due to thermal expansion or uneven force, resulting in uneven wear of the impeller and abnormal bearing load, shortening the service life of the equipment.
Solution by Longgang Pump Industry
- Impeller Semi-ring Positioning Design: The first-stage impeller adopts semi-ring positioning, allowing axial clearance to avoid the shaft deformation problem caused by temperature changes and eliminating the impact of thermal stress on the shaft system from the structure.
- Rotor Dynamics Optimization: By analyzing the force on the shaft system through finite element analysis, a design method for stable operation is established to ensure vibration stability under wide voltage (380V~10000V) and frequency (50/60Hz) working conditions, improving the service life of the bearings and impellers.
Cavitation Damage and Adaptability to Special Working Conditions
Fault Phenomena
The liquid vaporizes and produces bubbles when the pump’s suction pressure is less than the liquid’s vaporization pressure. When these bubbles burst, the impeller’s surface experiences cavitation, or metal fatigue erosion, along with noise and vibration. In extreme circumstances, it may result in impeller failure and perforation.
Solution by Longgang Pump Industry
Our closed test bench can replicate difficult on-site working conditions (such as high altitude and high-viscosity media) and has unique testing capabilities for ultra-high and ultra-low cavitation. The impeller’s service life is increased by optimizing the impeller’s inlet parameters and material treatment (identified by spectral analysis), as well as by using online monitoring technology to gather cavitation vibration signals in real-time and issue early warnings.
Energy Consumption and Environmental Protection Issues, and Green Manufacturing
Fault Phenomena
Traditional casting procedures are highly energy-consuming and create pollution from waste sand, thereby resulting in unstable performance of the pump body materials and harming the long-term operating reliability.
Solution by Longgang Pump Industry
The issue of excessive energy use in the casting process is addressed by green energy technologies, such as waste heat recovery from air compressors for heating. By achieving self-circulation and thorough usage of solid waste from waste sand in the park, the sand treatment system lowers carbon emissions and pollutant emissions at their source. By preventing early failure brought on by material flaws, the green manufacturing process guarantees the uniformity and stability of the pump body materials (as shown by an ultrasonic flaw detector and mechanical property testing equipment). In addition, it makes items more competitive in the high-end market and aligns with the global trend toward environmental conservation.
Conclusion
Based on multi-physical field coupling analysis technology and a full-working-condition verification platform, Longgang Pump Industry has creatively developed systematic solutions like self-adaptive control, thermal compensation sealing, vibration suppression, and cavitation early warning in response to the common issues that arise during the operation of centrifugal pumps, including overpressure risks, seal failures, abnormal vibrations, shaft system deformations, and cavitation damages. These technologies can successfully save maintenance costs, increase the lifespan of important components, and provide steady performance even in the most demanding operating environments.
Contact our technical team right now to obtain a customized centrifugal pump solution and full-life-cycle operation and maintenance support!
