1. Double screw air compressor

The complete system of screw compressor is mainly composed of motor, compressor, pipeline, valve and pressure vessel. During operation, it will be subjected to loads such as air force, inertia force and friction force, which will stimulate the vibration of compressor casing, complete chassis, piping system and support structure, as well as parts and components. These vibrations will bring a series of problems if they are not limited by appropriate measures.
Screw compressor noise is mainly divided into mechanical noise and hydrodynamic noise. Under the action of alternating stress of motor, screw compressor causes collision, friction and vibration of components and parts in mechanical equipment, resulting in mechanical noise. Common control methods include controlling the noise source at the source, such as reducing the impact of moving parts, improving the dynamic balance of rotor and its assembly, etc.

2. Main motor and fan

The main motor noise is mainly electromagnetic noise and aerodynamic noise caused by the high-speed rotation of the cooling fan at the tail of the motor. In motor, electromagnetic noise is caused by the vibration of stator and rotor caused by the electromagnetic force wave generated by the harmonic magnetic field in the air gap between stator and rotor.
In order to reduce the electromagnetic noise of the main motor, it is necessary to stabilize the power supply voltage of the user and improve the manufacturing and assembly accuracy of the motor.

3. Oil and gas tank noise

The screw compressor does periodic suction and exhaust during operation, coupled with the mismatch of internal and external compression ratio, it is easy to produce air flow pulsation, which is transmitted to the oil and gas tank through the exhaust pipe, inducing hydrodynamic noise.
The noise of the oil and gas tank can be attenuated by attenuating the exhaust pulsation pressure, and installing an air flow pulsation attenuator at the exhaust outlet, which can attenuate the air flow pulsation or add an exhaust buffer. The larger the buffer volume is, the lower the sound frequency is, and the more noise is reduced. However, it is difficult to use in practice and is rarely used.

4. Piping system

The noise of the pipeline system is mainly the noise generated by the friction pipeline of pressurized gas or the disturbance of surrounding air caused by sudden decompression and evacuation.
The noise of the valve is mainly due to the following reasons:
① Noise caused by check valve vibration;
② The ram valve leaks.
③ The noise generated by the vibration of the check valve mainly comes from the lifting check valve.
Generally, the check valve is installed at the outlet of the compressor and pump to prevent the high-pressure air and liquid from returning to the system when the compressor and pump are stopped.

5. Loading and unloading noise

When the compressor is loaded and working, the air inlet valve is opened, and the air flow is compressed by the air end suction . The noise generated in the compression process is radiated from the air inlet in the form of sound waves, which produces air inlet noise. The noise at the inlet of the compressor shows obvious high-frequency characteristics, and the intensity of the noise increases with the increase of the load. In addition, the noise of the air inlet is related to the structure of the main engine, the diameter of the air inlet valve, the structure of the valve, etc.

The buzzing noise during unloading is a normal unloading deflation sound. If there is abnormal noise and vibration, check the bearings of the air end , main motor and fan motor.