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How to Deal with High Noise in Rotary Vane Vacuum Pumps?

Vacuum pump exhaust filters

Vacuum pump exhaust filters are installed on the exhaust port of rotary vane vacuum pumps, also known as oil mist separators. For the pump, vacuum pump exhaust filters are a good helper, helping the pump to save energy and reduce emissions, and helping vacuum application manufacturers to save costs.

The operation of rotary vane vacuum pumps will inevitably produce some vibration and noise, which depends on the quality of the pump to determine the size of the vibration and noise.

However, it cannot be ruled out that the noise will increase due to pump failures. So, what should vacuum application manufacturers do when they encounter large vibrations or noises in the pump?

The smooth exhaust of the vacuum pump exhaust filter can alleviate the noise of the pump. Normal noise refers to the noise level measured by tools when the pump reaches the limit vacuum. Excessive sound will affect the working environment, affecting the state of the staff, making people feel restless and unable to work.

The source of the pump’s noise is multi-faceted, including motor-generated noise, additional noise during the start-up phase of the pump, noise generated during operation under different inlet pressures, and noise generated when the gas valve is opened for operation.

Therefore, reducing the noise level is not an easy task. Is there any way we can minimize the operating noise of the equipment? The answer is yes. The following are the different degradation methods summarized by BTLAS for possible noise-generating situations.

High suction rate, impact of gas mixture on baffle plate
If the baffle plate is tight, the noise generated can be ignored, but if it is loose, it will increase the noise level. Therefore, the baffle plate needs to be tightened and have good rigidity. When in contact with the oil tank, rubber can be used to reduce vibration and noise, and also strengthen the effect of oil blocking.
Vane hits cylinder wall, increasing noise

The situation where the vane hits the cylinder wall may be caused by the vane running unsmoothly or the dead air gap causing the oil to be unable to compress, making it difficult for the vane to always stick to the cylinder wall. Therefore, the vacuum design should be transformed to eliminate dead spaces and use the method of dividing the exhaust and intake ports with arc surfaces.

There are certain defects in this method, such as the fact that there is only a narrow strip between the head of the vane and the rotor or the vane groove. If the sealing performance is poor at the cutting point, it will cause the pump suction speed to decrease, directly affecting the degree of vacuum.

Note that if the gap between the vane and the groove is too large, it will also affect the performance of the pump. The manufacturer of the vacuum pump exhaust filter, BTLAS, recommends maintaining a reasonable tolerance between the two and considering the expansion of the pump due to high temperature, leaving a certain safety distance, so the vane requires better spring force.
Valve disc collides with valve seat and support member, producing noise

The higher the suction speed of the pump, the larger the circulating oil volume, the greater the noise of the valve disc, the larger the area of the valve, the higher the valve jump, and the greater the noise of the valve disc. In addition, the material of the valve disc is also a factor. For example, rubber valve discs have better sound insulation effects than steel plates or laminated boards.

Therefore, it is necessary to control the amount of oil entering and close the valve disc in time. Pay attention to the selection of materials and structure of the valve.
Box echo and bubble bursting sound are also sources of noise

When communicating with the atmosphere or turning on the gas valve, this noise will become more obvious. It can be solved by reasonably adjusting the gas valve opening.

Today, the exhaust filter manufacturer BTLAS shared the noise generated by the impact of gas mixtures on the baffle plate, unreasonable vane design, vane hitting the cylinder wall, valve discs, and gas valves on the pump noise, and also provided solutions.

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