Chuck Yung
Technical Support Specialist
Electrical Apparatus Service Association, Inc.
St. Louis, MO
In his paper presented at the EASA Convention 2004, Chuck Yung provides a comprehensive guide to pump repair, emphasizing the importance of regular maintenance and efficiency improvements. Yung begins by highlighting the natural fit between motor and pump repair, noting that most pumps are motor-driven and should be serviced alongside the motor. He stresses the need to educate customers about the importance of regular pump maintenance, as pumps are often neglected compared to motors.
Yung discusses the significance of pump efficiency, explaining that system efficiency is determined by both motor and pump efficiency. He illustrates how improving pump efficiency can lead to substantial gains in overall system efficiency, far exceeding the benefits of upgrading motor efficiency alone. Pumps can lose approximately 2% efficiency per year in benign environments, and even more in corrosive or abrasive conditions. Yung outlines several methods to improve pump performance, including impeller and bowl repair, efficiency enhancement techniques, and testing procedures.
One key aspect of pump repair is ensuring the correct impeller diameter for the pump's horsepower rating. Yung explains that impellers are often used for multiple pump ratings and must be trimmed to the correct diameter to avoid overloading the motor. He provides guidelines for calculating the required impeller diameter based on horsepower and emphasizes the importance of final testing under load to verify performance.
Wear ring clearance is another critical factor affecting hydraulic efficiency. Yung provides recommended clearances and explains the impact of excessive clearance on efficiency. He also discusses the use of O-rings and gaskets to exclude water from submersible pumps, noting that proper compression is essential for effective sealing.
Yung compares mechanical seals to packing glands, highlighting the advantages of mechanical seals in terms of lower friction loss, reduced leakage, and higher reliability. He explains the process of converting a packing gland to accept a mechanical seal and the importance of selecting suitable seal materials based on the pumpage and service environment.
Efficiency improvement techniques include filing the leading edge of impeller blades to reduce turbulence, smoothing interior surfaces, and using specialty coatings to enhance surface finish. Yung provides potential efficiency gains for each method and emphasizes the importance of educating customers about these improvements.
Testing repaired pumps for leaks and performance is crucial. Yung outlines various testing methods, including dead-heading the pump to measure pressure and ensure proper impeller positioning. He also discusses the importance of checking submersible pump cables for damage and ensuring proper impeller mounting.
In conclusion, Yung emphasizes the opportunity for service centers to improve pump performance and efficiency through regular maintenance and repair. He encourages collaboration with end users to maximize energy savings and enhance pump reliability.
Key Points Covered:
- Importance of regular pump maintenance and efficiency improvements
- Methods for improving pump performance, including impeller and bowl repair
- Ensuring correct impeller diameter for horsepower rating
- Impact of wear ring clearance on hydraulic efficiency
- Advantages of mechanical seals over packing glands
- Efficiency improvement techniques, such as filing impeller blades and using specialty coatings
- Testing repaired pumps for leaks and performance
- Checking submersible pump cables and ensuring proper impeller mounting
Key Takeaways:
- Regular pump maintenance is crucial for improving efficiency and reliability
- Correct impeller diameter is essential to avoid motor overload
- Wear ring clearance significantly affects hydraulic efficiency
- Mechanical seals offer numerous advantages over packing glands
- Various techniques can enhance pump efficiency and performance
- Proper testing and inspection are vital to ensure repaired pumps function correctly
- Collaboration with end users can maximize energy savings and pump reliability
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