Pump failure often occurs during water pump operation. When we encounter some failures, we need to clearly understand the causes of these water pump failures and find the most correct solutions.
Learn how to troubleshoot a pump failure, understand the causes, symptoms and how to prevent pump failure in advance.
What are the main causes of water pump failure?
1. Pump Mechanical Seal Failure
When the cooling water in the mechanical seal of the water pump is insufficient or blocked, or the corrosion resistance of the sealing element lining material is low, it usually causes pump failure and liquid leakage.
2. Impeller Failure
The impeller is an important part of the centrifugal pump. When foreign matter blocks the impeller or the pump wears out during long-term operation, it may cause pump failure.
3. Pump Cavitation
Pump cavitation is one of the important reasons for pump failure. When the suction pipe breaks, causing air to enter the water pump pipe, or the pump’s NPSHa is lower than the standard, the water pump is prone to cavitation.
4. Bearing Failure
During the long-term operation of the water pump, the pump bearing and the pump body will rub against each other, or there will be too many impurities in the lubricating oil in the bearing, which will cause the bearing temperature to be too high and lead to water pump failure.
5. Pump Blockage
When foreign matter blocks the water pump inlet, the liquid temperature is too high, or there is a large amount of air in the pump, the water pump will not discharge liquid.
6. Pump Overheating
When the actual flow rate of the water pump is less than the designed flow rate, the pump will generate excess power consumption, causing the temperature of the pump to rise. Long-term overheating will damage the pump.
7. Installation Problems
When assembling the pump, if the pump manufacturer does not assemble the pump correctly or the accessories are not of the right specifications, the gap between the spare parts in the pump will be too large, which will eventually lead to pump damage.
8. Electrical Problems
Power supply is an important indicator in the operation of water pumps. Stable power supply will avoid changes in pump pressure due to voltage fluctuations, which may cause damage to the pump.
9. Lubricating Problem
Lubricating oil can help the rotating parts in the water pump operate better and prevent excessive friction between pump components. When the lubricating oil is insufficient or there are too many impurities in the lubricating oil, the water pump will not function properly.
10. Lack of Maintenance
Any pump requires regular maintenance. You can refer to the maintenance manual provided by the pump manufacturer and regularly maintain the pump according to the regulations to minimize pump failure.
What are the symptoms of water pump failure?
1. No Liquid Discharge
2. Insufficient Flow
3. Noise
4. Pump Vibration
5. Bearing Overheating
6. Pump Overheating
7. Pump Mechanical Seal Leakage
8. Gasket Leakage
9. Increased Power Consumption
💡 How do I troubleshoot a pump failure?
1. No liquid discharge
First, you need to determine the specific reason why no fluid is draining. Below are possible causes and specific solutions.
| No liquid discharge reasons | Solutions |
| 🔸Foreign matter blocks the impeller or inlet valve 🔸Pump inlet height is too high 🔸Suction pipe is damaged and air enters 🔸Centrifugal pump is not filled with liquid before starting 🔸The temperature of the delivered liquid is too high 🔸Inlet and outlet valves are damaged | 🔸Remove foreign matter from the impeller or valve 🔸Reduce the height of the pump inlet 🔸Replace the pipe gasket 🔸Reduce the temperature of the liquid 🔸Replace the valve |
2. Insufficient pump flow
When the pump flow rate is lower than the design flow rate, the following checks should be performed and resolved based on actual conditions.
| Insufficient pump flow reasons | Solutions |
| 🔸Impeller reversal 🔸Severe impeller abrasion 🔸Inlet valve blockage 🔸Excessive wear of pump inlet seal 🔸Pipeline leakage | 🔸Change the direction of impeller rotation 🔸Replace the impeller 🔸Clean up foreign matter in the inlet valve 🔸Replace the pump inlet seal 🔸Tighten the pipe connections |
3. Abnormal sound
When the pump is running, the noise is too loud or the sound is abnormal. The following reasons may be the following.
| Abnormal sound reasons | Solutions |
| 🔸Foreign matter has entered the pump 🔸Friction between the impeller and the pump body 🔸Bearing damage | 🔸Remove foreign matter in the pump 🔸Adjust the thickness of the pump cover gasket to prevent friction between the impeller and the pump body 🔸Replace the bearing |
4. Pump vibration
When the pump vibrates, it should be handled in time. If the pump vibrates violently, turn off the power. The following are common causes and solutions.
| Pump vibration reasons | Solutions |
| 🔸The coupling is skewed 🔸The pump shaft is bent 🔸The impeller is skewed 🔸The anchor bolts are loose | 🔸Repair the coupling 🔸Adjust or replace the bearing 🔸Replace the impeller 🔸Tighten the anchor bolts |
5. Bearing overheating
When the pump shaft temperature is too high, there may be the following reasons and solutions.
| Bearing overheating reasons | Solutions |
| 🔸Too little lubricating oil or too many impurities in the lubricating oil 🔸Bearing damage 🔸Friction between the bearing and the pump body | 🔸Clean the bearing and replace the lubricating oil 🔸Replace the bearing 🔸Increase the thickness of the bearing gasket |
6. Pump overheating
When the temperature of the pump is too high during operation, the following reasons may be the cause.
| Pump overheating reasons | Solutions |
| 🔸The outlet valve is not open or is blocked 🔸The flow rate of the pump during actual operation is too small, lower than the design flow rate 🔸The impeller is blocked | 🔸Open the outlet valve or remove foreign matter 🔸Replace a pump with a smaller flow rate or increase the flow rate 🔸Remove foreign matter from the impeller |
7. Pump mechanical seal leakage
Common causes and solutions for mechanical seal leakage.
| Pump mechanical seal leakage reasons | Solutions |
| 🔸Insufficient cooling water 🔸Insufficient spring pressure 🔸Damaged seal | 🔸Clean the cooling water pipe 🔸Increase the cooling water volume 🔸Adjust the spring pressure, and replace the seal |
8. Gasket leakage
Common causes and solutions of gasket leakage.
| Gasket leakage reasons | Solutions |
| 🔸Loose fastening bolts 🔸Damaged sealing points | 🔸Tighten the bolts appropriately 🔸Replace the gasket |
9. Increased power consumption
The reasons for the sudden increase in power consumption are as follows
| Increased power consumption reasons | Solutions |
| 🔸Friction between the pump shaft and the inlet seal 🔸Parts stuck 🔸The center line of the pump shaft is offset | 🔸Adjust the pump shaft 🔸Check the pump parts 🔸Adjust the center line of the pump shaft |
How to prevent pump failure? Pump Maintenance
Daily maintenance is one of the important ways to prevent pump failure and extend the service life of water pumps. So what are the daily maintenance and what should you pay attention to? The following five maintenance common senses must be known.
1. Lubrication
During the operation of the centrifugal pump, the conveying medium, water and other items may enter the oil tank, affecting the normal operation of the pump.
The oil of a new pump should be changed once after one week of operation. The oil of a pump with a changed bearing during overhaul should also be changed. Because foreign matter enters the oil when the new bearing and shaft are running, the oil must be changed.
Therefore, we should check the quality and oil level of lubricants frequently. To check the quality of lubricants, we can observe with the naked eye and take samples for analysis regularly. The amount of lubricating oil can be seen from the oil level mark.
In the future, the oil should be changed once every quarter. The grease and lubricating oil used in chemical pumps must meet the quality requirements.
2. Vibration
During operation, the pump often vibrates due to poor quality of spare parts and maintenance, improper operation or pipeline vibration.
If the vibration exceeds the allowable value, stop the machine immediately for inspection to avoid damage to the machine.
3. Bearing temperature rises
During the operation of the pump, if the bearing temperature rises quickly, and the bearing temperature is too high after the temperature rise stabilizes, it means that there is a problem with the manufacturing or installation quality of the bearing.
Or the quality, quantity or lubrication method of the bearing lubricant does not meet the requirements. If not handled in time, the bearing is in danger of burning out.
The allowable value of bearing temperature is: sliding bearing <65℃, rolling bearing <70℃.
This allowable value refers to the allowable range of auxiliary bearing temperature after running for a period of time.
For newly replaced bearings, the bearing temperature will rise higher at the beginning of operation. After running for a period of time, the temperature will drop slightly and stabilize at a certain value.
4. Operation performance
During the operation of the pump, if the source of the liquid does not change, the opening of the valves on the inlet and outlet pipelines does not change, but the flow rate or inlet and outlet pressure changes, it means that there is a fault in the pump or pipeline. Eliminate it in time, otherwise it will cause adverse consequences.
5. Noise
Some of the noises made by the pump during operation are normal, while others are abnormal.
For abnormal noises, the cause should be found out and eliminated in time. There are roughly the following reasons for abnormal noises of the pump.
a. Fluid reasons: such as insufficient pump inlet flow, causing cavitation and noise. Water hammer and impact noises in the pump outlet pipeline.
b. Mechanical reasons: bearing quality does not meet requirements or is damaged. The gap between the moving and static parts of the pump is too small, causing friction. Parts are damaged and fall off, and foreign objects enter the pump.
