Causes and Solutions for Excessive Noise in Magnetic Drive Pumps

Industry pain points of magnetic drive pump noise.

Magnetic drive pumps are known for their sealless design and zero leakage performance, and are widely praised in the chemical and pharmaceutical industries. However, some users reported that the operating noise of magnetic drive pumps exceeded 75 dB(A) (refer to GB/T 3215 standard), which not only disturbed the workplace, but also may indicate potential risks in the equipment.

This article uses more than 20 years of engineering expertise to analyze the sources of magnetic drive pump noise and provide feasible solutions.

1. Cavitation

Root Causes：

-In the sealing structure of the magnetic drive pump, if the pipeline medium is in an over-concentrated state (such as containing too much gas or cavitation products), it will cause excessive internal pressure and fluid decompression, resulting in obvious cavitation and vibration noise during pump operation.

- Insufficient inlet pressure (NPSH margin <3 meters

- The medium temperature causes the vaporization pressure to rise

Symptoms:

- High-frequency "crackling" noise resembling pre-boiling water  

- Vibration acceleration exceeding 4.5 mm/s² (ISO 10816-3)  

Solution:

- Open the exhaust port of the magnetic drive pump body or discharge the exhaust gas inside the system to reduce the gas accumulation state.

- Adjust the concentration of the conveying medium according to the medium flow rate during use to avoid an overly thick state.

- Improve the suction conditions: increase the inlet pipe diameter (flow velocity ≤ 1.5m/s), install an inducer (increase NPSH margin by 30%) 

 2. Bearing Wear & Lubrication Failure  

Reason analysis:

-  Due to the large moment of inertia generated during the operation of the magnetic drive pump, if it is not replaced or adjusted in time, the sound quality during the operation of the pump will be unstable, resulting in vibration and noise problems.

Performance characteristics:

- Normal bearing noise: <68dB (A weighted), noise after wear: 75-85dB, accompanied by abnormal metal friction noise

Solution:

- Check regularly, if severe wear is found, replace it in time

- Upgrade the bearing and lubrication system, recommend bearing material silicon carbide (SiC) or silicon nitride (Si3N4), lubricant perfluoropolyether (PFPE) high temperature grease, the life is about 4 times longer than ordinary lithium-based grease.

3. Solid Particles & Viscosity Issues  

Contamination Thresholds

- 5% sand content → +8 dB noise  

- Viscosity >50 cP → +6 dB noise  

Solution:

- Make good filtration and medium pretreatment plans to prevent such problems from happening

- Use Y-type filter (mesh size ≥ 40 mesh)

- Add online viscometer to realize real-time alarm function

4. Improper Installation  

Cause analysis:

-There are certain problems with the installation method and installation position of the magnetic drive pump, resulting in other minor noise problems

Performance characteristics:

- When the foundation rigidity is insufficient, the vibration amplitude can be amplified 3-5 times

Solutions:

- Install rubber shock-absorbing pads (vibration transmission rate ≤ 10%)

- The thickness of the concrete foundation at the installation location is ≥ 3 times the weight of the equipment

- Install rubber vibration isolators (natural frequency < 5Hz))

 5. Magnetic Eddy Current Losses  

Cause analysis:

-  Eddy current loss in magnetic drive pumps refers to the energy loss and noise caused by the induced current in the fluid due to the action of the alternating magnetic field. This phenomenon mainly occurs when the fluid blades at the impeller inlet change, forming eddy currents, causing the blades to produce a roar or noise during operation.

Performance characteristics:

- The blades make a roaring sound when they rotate

Solution:

- Improve the material of the magnetic drive pump isolation sleeve, use high-resistance materials such as Hastelloy C276 to reduce the hysteresis effect

- NdFeB magnets are magnetized in sections (reduce eddy current loss)

- Adjust the gap of the magnetic coupler (standard value: 1.5-2.0mm)

It is also recommended to use the Internet of Things solution for intelligent monitoring and early warning, install vibration sensors and temperature sensors (such as 4-20mA output) for magnetic drive pumps, and use the cloud monitoring platform to realize real-time collection, data transmission and fault early warning of equipment status information, especially regular reminders through SMS and other methods. In addition, it is possible to consider introducing probe detection technology or other non-contact measurement equipment to further improve the accuracy and reliability of equipment health monitoring.

Through systematic maintenance and fixed management measures, the occurrence of abnormal conditions in magnetic drive pump equipment can be effectively reduced, thereby reducing the impact of noise problems on equipment operation and providing preventive measures for potential failures.