A gas compressor is a device used for compressing gases, and centrifugal compressors are widely used, similar in structure to pumps. The displacement of the permanent magnet variable frequency air compressor and the variable frequency screw air compressor can be combined with the user's gas consumption, completely avoiding the loss of unloading power; Under intermittent gas usage, the zero load effect of soft start avoids peak current and torque, allowing the unit to start and stop. Most of them are reciprocating pistons, rotating blades or rotating screws, and noise control mainly uses mufflers, creating a soundproof cover, and so on.

1、air compressorInstall muffler

The main sources of noise (decibels (dB)) are imports and exports, and appropriate intake and exhaust mufflers should be selected. The frequency spectrum of the inlet noise of an air compressor has low-frequency characteristics. Small holes should be used at the outlet of the air compressorImpedance typeSilencer. The intake muffler should use a resistance structure or an impedance composite structure with resistance and resistance, with high exhaust pressure and high wind speed.

2. Create a soundproof enclosure

After installing the muffler at the inlet and outlet of the air compressor or in the muffler channel, the airflow noise (decibels (dB)) can be reduced to below 80 decibels (a). If the sound absorber is hung on the ceiling of the factory, the noise (decibels (dB)) of the building can be reduced by 3-10dB (a), and the reverberation time can be shortened by 5-10 seconds. However, the mechanical noise and motor noise of the air compressor are still high, so the unit of the machine should also be equipped with a soundproof cover under air pressure.

3. Set up a silent pipeline

The use of underground or semi underground soundproof pits and silent tunnels can greatly reduce the intake noise (decibels (dB)) of air compressors, and have a longer service life than traditional mufflers. The pit walls are made of sound-absorbing bricks. The displacement of the permanent magnet variable frequency air compressor and the variable frequency screw air compressor can be combined with the user's gas consumption, completely avoiding the loss of unloading power; Under intermittent gas usage, the zero load effect of soft start avoids peak current and torque, allowing the unit to start and stop

How to reduce the noise at the exhaust port of an air compressor

Air compressors with high exhaust pressure and high flow rate generate high exhaust noise, and a muffler needs to be installed in the exhaust system for control. The exhaust muffler requires a large amount of noise reduction, a wide frequency band for noise reduction, and the ability to reduce pressure and expand capacity, as well as minimize the pressure drop during exhaust venting, in order to reduce exhaust venting noise.

For air compressors with a flow rate of less than 20m ³/min and low noise mainly at high frequencies, resistive mufflers can generally be used. The advantage of a resistive muffler is that it can reduce noise over a wide range of medium to high frequencies, especially for high-frequency sound waves. A resistive muffler utilizes porous sound-absorbing materials (commonly referred to as resistive materials) with different structural forms inside the airflow duct to absorb sound energy and reduce noise. It is a type of muffler with various forms and wide applications, and has a wide range of noise reduction frequencies. Its noise reduction performance is particularly significant in the middle and high frequency bands. There are several types of resistive silencers: tubular silencers, elbow silencers, chamber silencers, and disc silencers.

    However, for air compressors with high exhaust pressure and flow rate, due to the high noise pressure level, there are both mid low frequency and high-frequency noises. Relying solely on resistive mufflers is not ideal. Composite mufflers are an effective way to solve the problem. The forms of composite mufflers include impedance composite, resistive and resonant composite, resistance and micro perforated plate composite, etc. Composite mufflers combine the advantages of the former. Although resistive mufflers have excellent mid to high frequency noise reduction performance, their low-frequency noise reduction performance is poor and difficult to improve. On the other hand, expansion and resonance mufflers have the opposite effect, with good noise reduction performance at low to medium frequencies and generally poor high-frequency noise reduction effect.

   If the two noise reduction principles of resistance and impedance are combined into one type of muffler, satisfactory noise reduction effects can be obtained over a wide frequency range. This type of muffler has acoustic filtering elements such as resonance chambers, expansion chambers, perforated screens, and perforated sound-absorbing materials, which have sound-absorbing effects on noise of different frequencies.

    How to reduce the noise of the air compressor body

    To control the body noise and motor noise of the air compressor, it is commonly considered to use sound insulation and absorption control technology. The measure is to install soundproof enclosures or soundproof rooms on the compressor to prevent the spread of noise. This is because using only noise reduction measures cannot control radiated noise and electromechanical noise.

    Noise reduction at the air compressor inletAfter 10~20dB (A), the radiated noise of the chassis will become the main sound source. For small mobile air compressors, soundproof covers are often used as control measures; For large or multiple air compressors, soundproof rooms can be made in the machine room and operation room.

    In order to improve the sound insulation effect of the soundproof cover, a sound absorbing layer is usually attached inside it. If there is no sound-absorbing material inside the soundproof enclosure, the noise source will be continuously reflected by the steel plate without being absorbed, and a reverberation field will be formed inside the enclosure, resulting in an increase in sound level inside the enclosure. The higher the sound absorption coefficient of a material, the better its sound absorption ability, which varies with frequency, thickness, and density.

   The heat dissipation issue should be considered for soundproof enclosures and soundproof rooms. Usually, intake and exhaust mufflers are installed on soundproof bodies. The convenience of maintenance should be considered for soundproof equipment, with soundproof doors and observation windows installed for easy disassembly, and attention should be paid to making the joints tight after installation. Soundproof doors, soundproof windows, intake mufflers, and enclosures should maintain similar sound insulation levels. To improve the noise reduction effect of the soundproof enclosure, the design of the soundproof enclosure should meet the following requirements: the soundproof enclosure board should be made of materials with sufficient sound insulation, such as thin metal plates; Handle the weak sound insulation links such as doors, windows, and openings; Strengthen sound absorption treatment on the inner wall and select suitable sound absorbing materials.

   The elimination of noise from gas storage tanks is usually achieved by hanging sound absorbers. When compressed air enters the tank, the sound absorbing body inside the tank absorbs sound energy, thereby achieving noise reduction effect. To reduce exhaust pipe noise, the method of pipe wrapping or burying the pipe underground and using damping wrapping is adoptedThe inner layer is wrapped tightly with asphalt felt around the original pipeline, and its damping effect can weaken pipeline vibration and reduce pipeline regeneration noise; The outer layer is made of 3mm thick galvanized steel plate, and the middle layer is made of 50mm thick rock wool felt with a density of 150kg/m ³. The sound insulation wrapping achieved a noise reduction of nearly 20dB (A).

   How to reduce the vibration and noise of the air compressor body

To control the noise of the air compressor, it is necessary to control the vibration. The vibration of the air compressor is mainly transmitted outward through the foundation and pipeline system. The control of vibration mainly adopts isolation control. The main measures are as follows:

1. Use vibration isolators

The isolator forms an elastic connection between the air compressor and the foundation, reducing the amplitude to achieve vibration isolation, which is the key link in vibration isolation.

2. Adopt vibration isolation joint suspension foundation

The suspension foundation of the isolation joint cuts off the way in which the vibration of the air compressor is transmitted to the soil. The isolation joint is 150-200mm wide, filled with dry sand, and laid with dry sand and industrial felt under the foundation, with a felt thickness of 20-40mm.

3. Adopt vibration isolation ditch

In some cases, digging trenches on the ground can be used to cut off vibrations mainly caused by surface waves propagating along the ground.

Control the vibration of the air compressor pipeline to reduce the noise of the air compressor

   In the noise control of air compressors, there are usually two problems to be solved: vibration and radiation noise in the pipeline. The reason for the vibration of the air compressor pipeline is that the vibration of the air compressor is transmitted to the pipeline, and another reason is the vibration caused by the airflow pulse inside the pipeline. When the vibration frequency is between 20~20kHz, it is associated with sound and forms the sound radiation of the pipeline. The measures to control pipeline vibration and sound radiation are as follows:

1. The length of the resonant tube on the public wall. When the excitation frequency of the air compressor matches the natural frequency of the pipe system, resonance occurs, and the length of the pipe is the length of the resonance pipe.

2. Add orifice plates in the pipeline. Orifice plate is a resistance element that can reduce pulse airflow. The ratio of the aperture of the orifice plate to the diameter of the pipeline is D $L/D pipe=0.43-0.50. The thickness of the orifice plate is H=3-5mm. The orifice plate is installed at the inlet and outlet with large pulse and sufficient air volume.

3. Connect with a soft rubber hose to cut off the vibration along the pipeline. A section of metal tube is about to be replaced with a rubber tube, usually with a length greater than 0.5m.

4. Adopt elastic fixation at the fixed position of the pipeline to prevent vibration from being transmitted to the support.

5. Install a buffer muffler.

6. Wrap the pipeline with shock-absorbing material. For example, wrapping the air compressor pipeline with asphalt cloth can effectively reduce radiated noise

The standard specifies the emission limits and measurement methods for environmental noise at the boundary of industrial enterprises and fixed equipment factories(See Table 1)    Unit db (A)

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Safety Production Standardization Certificate Number:AQBJXXW202100026

quality management system (GB/T19001-2016 idt ISO9001:2015)Certification certificate:25021Q10338R0S

High tech Enterprise Certificate Number:GR202332017985

Da Shi "noise reduction equipment, payment will be made after installation is qualified!

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Address: Keyuan Village, Dunshang Town, Ganyu District, Lianyungang City (within the factory area of the muffler manufacturer)