Oil Sealed Rotary Vane Vacuum Pump Noise Too Loud

Identifying whether the sound of vacuum pump operation is normal is an effective method commonly used by maintenance personnel. Experienced masters can quickly find the problem through the sound. The normal operation sound of the vacuum pump should be smooth and low, and if there is a sharp sound and buzzing sound , friction sound, click sound, impact sound, it obviously needs to be detected and dealt with.

Generally, it is necessary to determine whether it is generated by the motor part. If it is not in the detection of the vacuum pump part, the common abnormal sound of the vacuum pump has the following reasons:

The oil level is too low

The muffler hole is blocked

The air inlet pressure is too high

The elastic coupling is worn

The blade or bearing is damaged

The cavity is worn

The motor part is abnormal


  • The oil level is too low (no oil can be seen in the observation window)

If the oil level is too low, the lubrication of the vacuum pump will be poor, the cooling will be poor, the wear resistance will increase, and the running sound will also increase.

Troubleshooting: add oil, and confirm that the oil level is between the maximum and minimum when the pump is running.


  • The muffler hole is blocked

When the internal muffler hole of the vacuum pump is blocked, because the liquid is incompressible, the oil-sealed vacuum pump will produce an oil hammer effect under the ultimate vacuum. At this time, the sound of the pump operation is obviously increased, and it is sharp. When the sound becomes significantly smaller when the gas ballast valve is opened or the inlet is opened a little, it can be sure that the muffler hole is blocked at this time.

Troubleshooting: clean or replace the muffler parts.


  • Air inlet pressure is too high

When the pump works under high pressure, due to the overload, the sound becomes significantly louder. User should check whether the internal oil mist filter is blocked. After the oil pump removes the gas ballast valve, user can see the oil mist filter. If the oil mist is clogged, it can cause the pump noise too loud. In addition, confirm whether the pumping speed of the pump matches.

Troubleshooting: reduce the air inlet pressure to reduce noise. Methods to reduce the inlet pressure: Increase the pumping speed or reduce the inlet gas flow.


  • Coupling or elasticity wear

Most of the motor and pump casing of oil-sealed rotary vane pump are directly connected, and the middle is composed of a coupling and an elastomer. The elastomer material is usually plastic. After long time running or when temperature is too high, the elastomer will be worn. After the elastomer and couplings are damaged, the pump has a distinct slamming sound when it starts and stops.

Troubleshooting: Replace or repair the coupling.


  • Bearing damage

Whether it is a needle roller bearing or a sliding bearing, long-term operation or foreign matter entering the pump cavity will cause it to wear out. Once the bearing is worn, the sound of the pump will become significantly louder and humming when it is running.

Troubleshooting: overhaul or replace the bearing and rotary vane.


  • Cavity or rotary vane wear

If the rotary vanes of the pump are worn, cracked, missing corners, etc., abnormal sound will also occur, and once dust or hard small particles are drawn into the pump cavity, the cavity is prone to wear and scratches, and the sound will also become louder.

Troubleshooting: Repair or replace the cavity and replace the rotary vane.


  • The noise comes from the motor part

Abnormal sound will also occur when the motor bearing is worn, phase loss, and rotor wear.

Troubleshooting: Repair the motor.


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