11/08/2026
What Should I Do If a Newly Purchased Centrifugal Pump Isn't Performing Well?
A newly purchased centrifugal pump should deliver the expected flow, pressure and stable operation once it is correctly installed and commissioned.
But what if the pump is running, yet the flow is too low, the pressure is unstable, the pump is noisy, or the motor is consuming too much power?
Don't immediately assume that the pump itself is defective.
In many cases, poor performance comes from incorrect selection, installation, operating conditions, or system configuration.
Here is a practical guide to help you identify the problem step by step.
💡 1. First, Understand What "Poor Performance" Means
Before troubleshooting, define the actual problem.
Typical symptoms include:
▪ Flow rate is lower than expected
▪ Discharge pressure is insufficient
▪ Flow or pressure fluctuates
▪ Pump produces abnormal noise or vibration
▪ Motor current is higher than expected
▪ Pump frequently loses prime
▪ Liquid temperature rises abnormally
▪ Mechanical seal leaks
▪ Cavitation occurs during operation
These symptoms can have completely different causes.
For example, low flow does not necessarily mean the pump is underpowered. The real problem could be excessive pipeline resistance, insufficient suction conditions, incorrect valve positions, or an unsuitable impeller.
💡 2. Why Can a New Centrifugal Pump Perform Poorly?
The Pump Was Not Properly Selected
This is one of the most important factors.
A centrifugal pump should be selected according to the actual operating conditions, including:
▪ Required flow rate
▪ Required head or discharge pressure
▪ Liquid viscosity
▪ Liquid temperature
▪ Density
▪ Solid content
▪ Suction conditions
▪ Operating frequency and speed
A pump that is too small may fail to provide sufficient flow or pressure.
However, oversizing a pump is not necessarily better. An oversized pump may operate far away from its Best Efficiency Point (BEP), resulting in excessive energy consumption, vibration, recirculation and accelerated wear.
The pump should match the actual duty point, not simply have a larger motor or higher rated capacity.
💡 3. Check the Installation Before Blaming the Pump
A correctly selected pump can still perform poorly if it is incorrectly installed.
Check the suction line
The suction pipeline is particularly important.
Look for:
▪ Blocked suction filters
▪ Partially closed valves
▪ Excessive pipe length
▪ Too many elbows or fittings
▪ Air leakage at pipe joints
▪ An undersized suction pipe
▪ Excessive suction lift
Any of these conditions can restrict the liquid entering the pump.
When the available NPSH is insufficient, the pump may experience cavitation.
What does cavitation look like?
Typical signs include:
▪ Crackling or gravel-like noise
▪ Strong vibration
▪ Unstable flow
▪ Pressure fluctuations
▪ Reduced pump performance
▪ Damage to the impeller over time
Cavitation is not simply a "noise problem." Continuous cavitation can seriously shorten pump service life.
💡 4. Check the Rotation Direction
For a centrifugal pump driven by an electric motor, the rotation direction must be correct.
If the motor rotates in the wrong direction, the pump may:
▪ Produce insufficient flow
▪ Generate inadequate pressure
▪ Consume abnormal power
▪ Operate inefficiently
This is especially important after electrical installation or motor replacement.
Always verify the manufacturer's specified rotation direction before normal operation.
💡 5. Check the Valves and Pipeline System
Sometimes the pump is working normally, but the surrounding pipeline system is creating the problem.
Check whether:
▪ The suction valve is fully open
▪ The discharge valve is in the correct position
▪ A check valve is installed correctly
▪ Filters or strainers are blocked
▪ The pipeline contains unexpected restrictions
▪ The actual pipe diameter matches the design
▪ There are excessive pressure losses
A centrifugal pump does not operate independently.
Its performance is determined by the interaction between the pump curve and the system curve.
If the system resistance is higher than expected, the actual operating point may move away from the required duty point, causing the flow rate to drop.
💡 6. Check the Liquid Being Pumped
The pump may have been selected based on incorrect assumptions about the process liquid.
For example, increasing liquid viscosity can significantly affect centrifugal pump performance.
Also pay attention to:
▪ Liquid temperature
▪ Density
▪ Viscosity
▪ Gas or air content
▪ Suspended particles
▪ Crystals or solids
▪ Foaming characteristics
A pump designed for a low-viscosity liquid may not perform as expected when handling a much more viscous product.
In pharmaceutical, food and cosmetic applications, this is especially important because product properties can change with temperature, concentration and formulation.
💡 7. Don't Ignore Air in the System
Air entering the suction line can cause unstable pump operation.
Possible sources include:
▪ Loose pipe connections
▪ Damaged seals
▪ Incorrect tank liquid level
▪ Poorly designed suction piping
▪ Vortex formation in the tank
▪ Inadequate priming
If air continuously enters the pump, you may observe fluctuating flow, noise, vibration or repeated loss of prime.
For hygienic applications, proper piping design is even more important because it must support both reliable operation and effective cleaning.
💡 8. A Practical Troubleshooting Sequence
If your new centrifugal pump is underperforming, don't randomly adjust different components.
Follow a systematic process:
Step 1 — Confirm the actual operating data
Record:
▪ Flow rate
▪ Suction pressure
▪ Discharge pressure
▪ Motor current
▪ Liquid temperature
▪ Pump speed
Compare the actual values with the original technical requirements.
Step 2 — Check the installation
Inspect:
▪ Pipeline connections
▪ Valve positions
▪ Filters
▪ Pipe diameter
▪ Air leakage
▪ Pump alignment
▪ Foundation and support
Step 3 — Check suction conditions
Make sure the pump has adequate liquid supply and sufficient NPSH margin.
Look for signs of cavitation or air entrainment.
Step 4 — Verify rotation and electrical conditions
Confirm motor rotation, frequency, voltage and operating speed.
Step 5 — Check the process liquid
Verify that the actual liquid properties are consistent with the original pump selection.
Step 6 — Compare the actual duty point with the pump curve
This is one of the most important steps.
If the actual flow and head are significantly different from the expected operating point, the pump may simply not be correctly matched to the system.
Step 7 — Contact the manufacturer
If the installation and operating conditions have been confirmed but the problem remains, provide the manufacturer with actual operating data.
A good supplier should be able to help analyze the problem instead of simply telling you to "increase the pressure."
💡 9. How Can the Problem Be Solved?
The appropriate solution depends on the actual cause.
If the pump is undersized:
Select a pump with a suitable flow/head range.
If the system resistance is too high:
Optimize the pipeline, reduce unnecessary restrictions, or review the valve and piping configuration.
If cavitation occurs:
Improve suction conditions, reduce suction losses, increase liquid level where appropriate, reduce liquid temperature if possible, or select a pump with more suitable NPSH characteristics.
If the pump is oversized:
Consider adjusting the operating point or selecting a more appropriate pump. In some systems, speed control or impeller trimming may also be considered, but these changes should be evaluated against the manufacturer's recommendations.
If air is entering the system:
Find and eliminate the air leakage source and review the suction piping and tank configuration.
If the liquid properties have changed:
Re-evaluate pump selection based on the actual viscosity, density, temperature and solids content.
The key is to solve the root cause rather than simply treating the symptom.
💡 10. How to Prevent Problems Before Purchasing a Pump
The best troubleshooting strategy is prevention.
Before purchasing a centrifugal pump, provide the supplier with as much accurate process information as possible.
At minimum, clarify:
1. Required flow rate
How much liquid needs to be transferred per hour?
2. Required head or pressure
What pressure does the process actually require?
3. Liquid properties
What are the viscosity, density, temperature and solids content?
4. Suction conditions
What is the tank level and suction arrangement?
5. Pipeline information
What are the pipe diameter, length, fittings and elevation differences?
6. Operating conditions
Will the pump run continuously, intermittently, or under variable conditions?
7. Hygiene and material requirements
For pharmaceutical, food and cosmetic applications, consider wetted materials, surface finish, sealing materials, cleanability and applicable hygienic requirements.
Providing accurate information allows the manufacturer to select a pump based on the real process conditions, rather than assumptions.
Final Takeaway
When a newly purchased centrifugal pump doesn't perform as expected, don't immediately conclude that the pump is faulty.
The root cause may be:
Pump selection → Installation → Suction conditions → Pipeline resistance → Liquid properties → Rotation → Operating point
A systematic diagnosis can help identify the real problem much faster and prevent unnecessary equipment replacement.
For pharmaceutical, food, cosmetic and chemical processes, choosing the right pump is not simply about achieving the required flow rate.
It is about achieving stable performance, reliable operation, hygienic processing and long-term value.
The right pump is not necessarily the biggest or most powerful pump — it is the pump that matches your actual process.
If you are selecting a centrifugal pump for a new production line or experiencing unstable pump performance, feel free to contact us with your flow rate, head, liquid properties and operating conditions. We can help you evaluate the appropriate pump solution.