The closer the exhaust port is to the upper cut point, the quieter the noise. But if it is too close, it will affect the performance of the rotary vane pump. The smaller the exhaust port, the smaller the noise, and vice versa, which means that the size of the exhaust port has a great influence on the noise.

When the rotary vane vacuum pump starts at atmospheric pressure, the pressure is high and the gas volume is large. The high and low vacuum chambers are used to exhaust at the same time, and most of the gas is discharged from the exhaust valve of the high vacuum chamber. Since the size of the exhaust port of the high vacuum chamber has no effect on noise, and can reduce the exhaust pressure and reduce the maximum compression work and starting power, the area of ​​the exhaust port of the high vacuum chamber should be larger. During normal operation, the exhaust valve of the high vacuum chamber is closed, and the main factor affecting the noise is the exhaust valve of the low vacuum chamber. Therefore, the area of ​​the exhaust port of the low vacuum chamber should be smaller to reduce noise; but if the exhaust port is too small, the exhaust pressure will increase, and the power consumption will increase. According to this, the size and position of the more suitable exhaust port are selected. Although these should be considered in the design and manufacture, the maintainer should also pay attention to it so as to improve the noisy pump during maintenance.

The principle of considering the position of the air inlet in the design is: the suction volume should be the largest, the volume utilization coefficient should be the largest, and the air resistance should be small.

When repairing the pump, pay attention to whether the filter screen of the air inlet is blocked, and whether foreign objects such as metal and glass debris have fallen into the air inlet, otherwise the pump cavity will be damaged.