Essential Guide for Centrifugal Pump Selection: How to Avoid Overload Failures

I. What is "Overload" in Centrifugal Pumps?

"Overload" in centrifugal pumps typically refers to the phenomenon where the power required during operation exceeds the motor's rated power. This leads to excessive current, motor overheating, and even tripping or burnout. Common causes include:

• Excessive flow (e.g., operating with fully open valves)
• Improper head selection
• Foreign objects entering the pump body or impeller blockage
• Abnormally high liquid viscosity or density
• Unstable voltage or three-phase imbalance

II. How to Avoid Overload During the Selection Phase?

To systematically prevent overload risks during centrifugal pump selection, focus on four key aspects: parameters, pump type, motor, and control systems:

1. Precise Positioning of Operating Parameters

Before selection, clarify the medium characteristics (clean water/sewage/corrosive liquid, viscosity, solid content), flow rate (normal/peak conditions), head (static head + pipeline loss), temperature, and pipeline layout (pipe diameter, number of bends). For example, when transporting sewage with impurities, parameter errors should be controlled within ±5%, and peak flow should have a 10% margin to avoid pump overload due to parameter deviations.

<table border="1" width="100%" style="border-collapse: collapse;"><tbody><tr><td colSpan="1" rowSpan="1">Parameter</td><td colSpan="1" rowSpan="1">Requirement</td></tr><tr><td colSpan="1" rowSpan="1">Flow Rate Margin</td><td colSpan="1" rowSpan="1">±5% accuracy; 10% peak margin</td></tr><tr><td colSpan="1" rowSpan="1">Viscosity</td><td colSpan="1" rowSpan="1">&lt;500 cSt for standard pumps</td></tr><tr><td colSpan="1" rowSpan="1">Solid Content</td><td colSpan="1" rowSpan="1">&lt;3% for non-clogging pumps</td></tr></tbody></table><br>

2. Optimal Matching of Pump Types in High-Efficiency Zones

Prioritize pump types with gentle Q-H curves (head increase ≤15% with flow rate) and ensure the actual operating point falls within the high-efficiency zone (60%-90% of rated flow). For a pump with a rated flow of 80 m³/h, the optimal operating range is 48-72 m³/h, avoiding low-flow high-head or high-flow low-efficiency conditions to reduce impeller wear and motor overload.

3. Scientific Redundancy of Motor Power

Configure motor power at 1.1-1.3 times the pump shaft power: use 1.1 times for low-viscosity media and 1.2-1.3 times for high-viscosity or impurity-laden media (e.g., viscosity >500 cSt, solid content >3%). For applications with variable loads, consider using a variable frequency drive (VFD) to optimize power consumption and reduce overload risks.

4. Integration of Intelligent Protection Systems

Install multiple protection layers in the control system:

① Overload Protector

Set current thresholds at 1.05-1.1 times the rated value to shut down immediately when exceeded.

② Frequency Converter

Achieve soft starting and dynamic flow regulation, controlling fluctuations within ±5%.

③ Intelligent Monitoring Module

Real-time tracking of current, temperature, and other data, with warnings triggered at 85% of rated load to identify potential risks in advance.

III. Prevention Measures During Operation and Maintenance

Even with proper selection, poor operation management can still cause overloads. Here are key maintenance recommendations:

1. Regular Operation Monitoring

Monitor parameters such as current, pressure, and vibration to determine if the pump is operating normally. Immediately shut down for inspection if abnormal current increases or pump body vibrations are detected.

2. Pipeline Unblocking

Regularly clean the inlet filter, impeller, and pipeline interior to prevent blockages that cause excessive flow or internal pressure buildup, leading to motor overload.

3. Avoid Frequent Start-Stops

Frequent starting imposes heavy impacts on motors, increasing overload risks. Set reasonable start-stop intervals and use variable frequency speed regulation for smooth adjustments.

4. Lubrication and Sealing Maintenance

Good lubrication reduces additional loads from mechanical friction, while intact sealing systems prevent energy loss and efficiency degradation caused by leaks. Proper training for operators ensures early detection of abnormal conditions and timely intervention.

Conclusion

As a leading brand in fluid handling solutions, TEFFIKO specializes in precision pump selection and full-cycle support—from design to operation—ensuring reliable performance across chemical, petroleum, water treatment, and other critical industries. As indispensable power equipment in industrial systems, the stable operation of centrifugal pumps directly affects overall system efficiency and safety. To avoid overload failures, users must prioritize parameter matching, motor configuration, and system design during selection. Choose TEFFIKO to eliminate overload risks from the source and unlock new heights of safety and efficiency in industrial fluid transportation.