Industrial noise control

China's "Noise Hygiene Standard for Industrial Enterprises" stipulates that the allowable noise value of industrial enterprises' production workshops and workplaces is 85dB (A). Existing industrial enterprises may relax their efforts when they fail to meet the standards temporarily, but they must not exceed 90dB(A).

Controlling noise should take technical measures from the three sources of sound sources, transmission paths, and human ears.

First, controlling and eliminating noise sources is a fundamental measure. Replacing loud equipment with silent or whispered equipment and processes through process reforms, such as replacing rivets by welding, replacing forging by hydraulics, replacing shuttle looms by shuttleless looms, etc.; strengthening machine maintenance or eliminating unnecessary Parts to eliminate the noise caused by machine friction, impact, etc.; The machine collides with external elastic materials instead of metal materials to buffer the impact force. For example, the ball mill replaces the steel plate with a rubber lining, adds a rubber gasket or copper-manganese alloy at the mechanical impact, and processes rolling. When the parts fall, they can fall into the pool instead.

Second, reasonable plant planning and plant design. There should be a certain distance or protective band in the production of strong noise workshops and non-noise workshops and residential areas; windows of noise workshops should be designed with non-noise workshops and residential areas to be 90 degrees; noise should be concentrated as much as possible in the workshop. Take sound insulation measures, install sound-absorbing materials indoors, and install or apply sound-absorbing materials on the walls to reduce reflection noise in the workshop.

Third, take measures against noise for local noise sources. Silencer devices are used to isolate and enclose noise sources; vibration isolation devices are used to prevent noise from propagating outwards through solids; epoxy resin is used to fill gaps between the rotor slots of the motor and the stator to reduce electromagnetic noise.

Fourth, control the propagation and reflection of noise. (1) Absorption: Use porous materials such as glass wool, slag wool, foam plastic, felt batting, etc., to decorate on the indoor wall or hang in the space, or make a sound-absorbing screen; (2) Muffler: use muffler to reduce Aerodynamic noise, such as noise from various fans, air compressors, internal olefins, etc.; (3) Noise: Enclose noise sources with certain materials, structures, and devices, such as sound insulation walls and sound insulation rooms. , Acoustic enclosures, soundproofed doors and windows floors; (4) Damping, vibration isolation and noise reduction: Damping is applied on the wall of the air duct with bitumen, paint, etc., to reduce the vibration of the wall; vibration isolation is in the noise source. Vibration damping devices and anti-vibration structures are installed on foundations, floors, and walls. For example, a vibration-proof rubber pad is installed on a hammer seat, and sand or the like is filled in the pipe of the pillar.

Fifth, personal protection. Due to technical or economical reasons, employees wearing noises that exceed national health standards often use personally worn earplugs, earmuffs or helmets to protect their hearing.

Sixth, regularly conduct hearing and body health checks on workers exposed to noise. If it is found that hearing loss in the high-frequency band exceeds the normal fluctuation range, the noise job position should be removed early. When a new worker takes a pre-employment medical examination, anyone with sensorineural deafness and significant cardiovascular and neurological structural diseases should not be allowed to take a rest in a noisy room; the working hours in a noisy environment should be shortened as much as possible; , And to carry out sanitary supervision on factories, mines and workshops with serious noise hazards, and urge them to take active measures to reduce noise in order to meet the requirements of noise hygiene standards.

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