How to Detect Pump Cavitation: Signs, Causes and Testing Tools Malaysia
Meta Description: Learn how to detect pump cavitation using vibration, noise, temperature, pressure and flow information in Malaysian factory maintenance applications.
A pump that produces a crackling or gravel-like noise may be experiencing cavitation.
Cavitation can cause unstable vibration, reduced flow, damaged impellers, seal problems and shorter pump life.
However, abnormal pump noise does not always confirm cavitation. Bearing damage, misalignment, air entering the system and loose components can produce similar symptoms.
Maintenance teams should evaluate vibration, sound, pressure, flow, temperature and operating conditions together.
What Is Pump Cavitation?
Cavitation occurs when the local pressure inside a liquid falls sufficiently for vapour bubbles to form.
When these bubbles move into a higher-pressure area, they collapse.
Repeated bubble collapse can create:
Noise
Vibration
Surface damage
Reduced pump performance
Unstable flow
Premature component wear
Common Signs of Pump Cavitation
Possible signs include:
Crackling or gravel-like sound
Increasing pump vibration
Unstable vibration
Reduced flow
Low discharge pressure
Fluctuating pressure
Reduced pump efficiency
Increasing motor current
Impeller damage
Repeated seal or bearing problems
No single sign confirms cavitation by itself.
Common Causes of Cavitation
Possible causes include:
Low suction pressure
Blocked suction strainer
Closed or partially closed suction valve
Undersized suction pipe
Long suction pipe
Excessive pipe bends
High liquid temperature
Low tank level
High pump speed
Incorrect pump selection
Excessive flow demand
High suction lift
Air leakage into suction line
Poor piping arrangement
1. Low Liquid Level
When the source tank level falls, the available suction pressure may decrease.
Check:
Tank level
Level-control operation
Suction-pipe submergence
Vortex formation
Air entering the suction line
Record pump vibration and noise at different tank levels.
2. Blocked Suction Strainer
A dirty or blocked strainer increases suction resistance.
Possible indications include:
Reduced pump flow
Lower suction pressure
Increasing noise
Increasing vibration
Changing motor current
Inspect and clean the strainer according to the approved isolation procedure.
3. Partially Closed Suction Valve
A partially closed valve can restrict flow into the pump.
Check:
Valve position
Valve condition
Damaged actuator
Incorrect control signal
Internal obstruction
Valve-identification labels
Never use the suction valve for flow control unless the pump and system are specifically designed for that operating method.
4. High Liquid Temperature
Warmer liquid generally vaporises more easily.
Cavitation risk may increase when pumping:
Hot water
Condensate
Heated process liquid
Volatile fluids
Measure actual fluid temperature using a suitable contact or immersion probe.
An infrared thermometer measures pipe-surface temperature, which may not equal the liquid temperature.
5. Excessive Pump Speed
Higher pump speed can increase suction demand.
Check actual RPM using a tachometer.
Possible causes include:
Incorrect variable-frequency drive setting
Wrong pulley ratio
Incorrect motor selection
Control-system error
Record speed with every vibration measurement.
6. Air Entering the Suction Line
Air leakage can produce noise, unstable flow and vibration that may resemble cavitation.
Inspect:
Flanges
Gaskets
Pipe joints
Valve stems
Pump seals
Flexible hoses
Suction fittings
Air entry and vapour cavitation are related but not identical conditions.
7. Incorrect Pump Operating Point
A pump operating too far from its intended operating range may experience:
Internal recirculation
Increased vibration
Reduced efficiency
Heat
Noise
Component stress
Review:
Flow
Suction pressure
Discharge pressure
Motor current
Pump speed
System resistance
How to Measure Pump Vibration
Use a vibration meter at consistent locations such as:
Pump drive-end bearing
Pump non-drive-end bearing
Motor drive-end bearing
Motor non-drive-end bearing
Measure in:
Horizontal direction
Vertical direction
Axial direction
Cavitation may produce unstable or broadband vibration, but a basic overall vibration reading cannot confirm the exact fault.
Vibration Meter Options
MTM Precision supplies:
Landtek VM-6310
Landtek VM-6360
Smart Sensor AR63B
Benetech GM63B
Wintact WT63A
Wintact WT63B
These instruments can support routine vibration checks and trending.
More detailed diagnosis may require advanced vibration-analysis equipment.
How to Check Pump Noise
A sound level meter can document changes in overall pump noise.
For repeatable measurements, record:
Measurement distance
Meter position
Frequency weighting
Response setting
Pump speed
Flow condition
Production load
A sound level meter measures noise level but does not automatically distinguish cavitation from bearing or mechanical noise.
Check Suction and Discharge Pressure
Pressure information is essential when investigating cavitation.
Record:
Suction pressure
Discharge pressure
Pressure fluctuations
Tank level
Flow rate
Fluid temperature
Pump speed
A vibration reading without system data may lead to the wrong conclusion.
Check Pump Flow
Reduced or unstable flow may support further investigation.
Flow changes may also result from:
Closed valves
Blocked filters
Pipe obstruction
Worn impeller
Process changes
Incorrect pump speed
Air inside the system
Use a suitable flow measurement method for the pipe and fluid.
Check Motor Current
A clamp meter can help identify changes in pump load.
Current may increase or decrease depending on:
Pump type
Flow condition
Mechanical resistance
Cavitation severity
Motor condition
System pressure
Compare current with previous readings under similar operating conditions.
Check Bearing Temperature
Use an infrared thermometer or thermal imaging camera to check:
Pump bearings
Motor bearings
Pump casing
Coupling area
Mechanical-seal area
Cavitation does not always cause an immediate temperature increase.
A hot bearing may indicate a separate lubrication, alignment or bearing problem.
Cavitation vs Bearing Damage
ObservationCavitationBearing ProblemGravel-like noiseCommon possible signLess typicalPressure or flow fluctuationPossibleUsually limitedChanges with suction conditionOftenLess directBearing temperature increaseNot alwaysPossibleVibration near pump casingPossiblePossibleContinues after flow condition changesMay reduceMay remain
This table provides investigation guidance, not a final diagnosis.
Cavitation vs Mechanical Looseness
Mechanical looseness may produce:
Knocking
Impact vibration
Loose mounting
Movement at the base
Damaged bolts
Cracked supports
Inspect the pump base, motor feet, anchor bolts and pipe supports before concluding that the pump is cavitating.
Basic Pump Cavitation Investigation
Step 1: Record Normal Operating Data
Note tank level, temperature, pressure, flow, speed and current.
Step 2: Listen for Abnormal Noise
Identify when the noise begins and whether it changes with flow.
Step 3: Measure Vibration
Check the pump and motor bearings at documented points.
Step 4: Check Suction Conditions
Inspect the valve, strainer, pipe arrangement and source tank.
Step 5: Verify Pump Speed
Measure RPM and check VFD settings.
Step 6: Check Pressure and Flow
Look for unstable or reduced performance.
Step 7: Inspect for Air Entry
Check suction-side connections.
Step 8: Compare with Previous Data
Determine whether the change was sudden or gradual.
Possible Corrective Directions
Depending on the confirmed cause, corrective work may involve:
Cleaning the suction strainer
Opening the suction valve fully
Increasing the source-tank level
Reducing pump speed
Reducing fluid temperature
Repairing suction-side air leaks
Improving suction piping
Selecting a more suitable pump
Adjusting the operating point
Removing pipe obstruction
Corrective action should follow the pump manufacturer and system-engineering requirements.
Common Cavitation Troubleshooting Mistakes
Avoid:
Diagnosing cavitation from noise alone
Ignoring suction pressure
Measuring vibration without recording RPM
Assuming every unstable reading is bearing damage
Replacing bearings before checking the suction system
Ignoring high fluid temperature
Closing the suction valve to reduce flow
Comparing readings under different tank levels
Ignoring air leakage
Continuing operation when severe vibration or damage is present
Recommended Pump Troubleshooting Instruments
Investigation RequirementRecommended InstrumentPump and motor vibrationVibration meterEquipment noiseSound level meterPump rotational speedTachometerMotor currentClamp meterBearing temperatureInfrared thermometerTemperature patternThermal imaging cameraFluid temperatureContact or immersion thermometerSuction and discharge pressureSuitable pressure gauge or manometerFlow performanceSuitable flow meter
Pump Cavitation Testing Tools Supplier in Malaysia
MTM Precision supplies instruments for investigating pump cavitation, vibration, abnormal noise, bearing temperature, motor loading and rotational speed.
Our available range includes vibration meters, sound level meters, tachometers, clamp meters, infrared thermometers, thermal imaging cameras and pressure-measurement instruments.
Contact MTM Precision
MTM Precision Sdn. Bhd.
Showroom & Service Centre
No. 29-1 & 29-2, Jalan Bandar 18,
Pusat Bandar Puchong,
47160 Puchong, Selangor, Malaysia
🌐 Website: www.mtmpre.com.my
📧 Email: mtmpre@yahoo.com
📱 WhatsApp: +6016-660 7346
31 Aug 2026
