Where possible, use modern construction equipment that has been designed specifically to produce less noise. Their shielding effect is mainly limited to the more directional high frequencies. The aim of the regulations is to simply reduce the likelihood of hearing loss as a result of excessive noise in their workplace – or other serious conditions such as tinnitus. The region enclosed may be that of the whole factory (to reduce the noise reaching residential areas in the neighbourhood), or only a small area of it (a single machine, for example). Sound-absorbing material should be used inside an enclosure designed to reduce noise. Similarly, the sound transmission through flanking floors may be critical if the noise reduction required is more than about 45 db. Noise Reduction at Source 2. Subsequently, there should be proper supervision to ensure that the ear protectors are worn regularly. In such cases, the cover should be isolated from the source by resilient fixings. In such cases, the material can be hung from the roof members in sheets, or in hollow fabricated shapes (which give increased absorption for the same quantity of material). A similar arrangement is necessary if a machine needs to be bolted down to achieve sufficient rigidity. Occupational noise is the amount of acoustic energy received by an employee's auditory system when they are working in the industry. The higher the ratio between the two frequencies, the greater the noise reduction; but it is difficult to achieve a very large reduction in practice. The load per unit area must be high enough to give deflection adequate for the isolation required. Textile and pollution: The textile process deals with production of fiber, yarn and fabric followed by pre and post chemical, mechanical process. Supporting structures for vibrating machines and other equipment will radiate less noise if they are frames than if they are cabinets or sheeted enclosures. wide, the noise reduction obtained at low frequencies is no better (and may even be worse) than for a solid wall of the same total weight. One way to reduce noise is through your engineering practices themselves. Factory engineers should see to it that open windows, doors, and other openings that allow high-frequency noise to escape from the factory, should not face neighbouring buildings. Vibration from rotating machinery can usually be reduced by dynamic balancing. The build-up of reverberant sound within an enclosure can be controlled by the use of sound absorbing materials. For example, noise caused by the handling and dropping of materials on hard surfaces can be reduced by the following methods: (a) By covering surfaces with resilient materials; (b) By using resilient materials for containers; and. In multi-storey factories (where the floors are more liable to vibrate, and to radiate noise both upwards and downwards), such isolation is an essential part of noise reduction. The typical noise reduction achieved by lining the roof of a factory with a sound absorbing material is shown in Fig. If reciprocating or vibrating movement is part of the work process, the amplitude of such a vibration should be kept to a minimum. Often a rattle can be eliminated merely by securing a loose panel. Since this is limited to about 20 dB, almost any sheet material having the strength to stand up to industrial use will be adequate. In the case of extremely high levels of noise, it may be necessary to use a combination of earplugs and earmuffs. How to reduce air pollution of the Earth's air, water and soil resources is an ongoing problem facing world governments. Ways to achieve this include: Modifying the paths which noise travels to those exposed can be one of the most effective ways to reduce noise pollution in the workplace. 2 as a function of average machine spacing. Noise pollution isn't just annoying: it can cause deafness, fatigue, and even psychological problems. Partial Enclosures and Screens 7. Coil springs of steel are very useful in giving large deflections for isolating low frequencies, but high frequencies may be transmitted along with the coils unless there is another resilient material in series with the spring. Overall, the proper and regular maintenance of equipment is vital to help reduce deterioration that creates even more noise pollution in the industrial workplace. The typical noise reduction obtained in the ear from well-designed earplugs and earmuffs is shown in Fig. Moreover, the directional characteristics of high- frequency noise should also be taken into account. The smaller the region, the greater the number of people who benefit from noise reduction. On the other hand, porous materials, and thin sheet materials mounted in panels over an airspace, are much more efficient as sound absorbers than heavy, hard-surfaced materials. 1 shows the typical decrease in sound pressure level with increasing distance from the source for an untreated factory with normal hard inside surfaces, and for a similar factory of same size with a lining of sound-absorbing material at the ceiling. Other potential sources of vibration and noise are unit heaters, dust extraction equipment, conveyors, cranes, and transformers. This, however, would only be so if the cavity between the walls were impracticably wide, and there were no indirect transmission through floor or ceiling. Noise may, for example, be radiated by the sheet metal enclosing the moving parts. If noise levels increase, at any point, be sure to check for worn down or faulty parts. For example, the reduction in vibration transmitted to the floor will enable the live-load allowance for vibration to be reduced, and the reduction of shock loading within the machine may increase its useful life. Wherever it is possible, the opening should face a wall covered with sound-absorbing material, or should be baffled with a screen of the same construction as the enclosure. Heavy machinery, power tools, schools of people and the necessary radio result in a chorus of noise for most of the day - sometimes at extremely loud levels. Noise pollution, also known as environmental noise or sound pollution, is the propagation of noise with ranging impacts on the activity of human or animal life, most of them harmful to a degree.The source of outdoor noise worldwide is mainly caused by machines, transport, and propagation systems. Since the average noise near the source is also lower, there is some relief for the machine operator in the treated factory, though the reduction in the peak noise levels is negligible. The reason is that, once a process has been selected and introduced in a factory, no amount of noise reduction treatment inside the factory is likely to reduce the noise level of one of the noisy processes to that of its quieter alternative. High level of noise is a disturbance to the human environment. If the answer to these questions is yes then you should consider making these changes. In cases where the rate of reciprocation is not important, decreasing this rate will reduce the noise, provided that loose parts are not excited to vibrate at a higher frequency. For such a screen to be effective, however, its height above the level of noise source must at least equal half its distance from the source. But the sound reduction factor of a double wall increases more rapidly with frequency than that of a solid wall, giving relatively greater reductions at high frequencies. We consider now the case of an impulsive noise source. Where impact is essential to the process (as in hammering and riveting, for example), the possibilities of reducing noise at the source are usually limited to using no more power than is absolutely necessary, and preventing unnecessary impacts. (f) Using silencers to control noise from automobiles, ducts, exhausts etc. Often the noise excites a high-frequency resonance. The double wall may give a higher average noise reduction than a single wall, though it is more effective only at high frequencies. On the other hand, increasing the damping will be more effective if the exciting force covers a wide range of frequency. If the top of the enclosure is open the noise reduction will be increased by placing the sound-absorbing material on the ceiling overhead. Ear protection, however, is not likely to be popular with factory workers unless they understand why it is necessary. In fact, the issue of industrial pollution has taken on grave importance for agencies trying to fight against environmental degradation. Community development or urban management should be done with long-term planning, along with an aim to reduce noise pollution. If the impact can be spread over a short period (and thus converted into more of a squeezing or shearing operation), an appreciable noise reduction is obtained. However, the values given in Table 1 are theoretical values. © 2017 EnvironmentalPollution - All rights reserved, Acoustic Doors used to Control Noise | Noise Pollution, Top 4 Ways to Reduce Noise at Office | Noise Pollution, Causes of Water Pollution in India (7 Answers), Causes of Water Pollution: Essay, Paragraph, Article and Speech. The cover should, moreover, be coated with a layer of damping compound of equal weight to reduce the effects of resonance. In very large undivided areas with relatively low ceilings, the noise level decreases continuously as the distance from the source increases. Urban air mobility is the new rising trend. If there are only a few noisy machines in the factory, placing the absorbing materials on screens or nearby surfaces will be the most effective solution. This article explains how you can take action now, starting with small steps. The typical decay of the noise level for an impulsive emission of sound every second is shown in Fig. Occupational noise, or industrial noise, is often a term used in occupational safety and health, as sustained exposure can cause permanent hearing damage.Occupational noise is considered an occupational hazard traditionally linked to loud industries … If, on the other hand, the sources of noise are distributed throughout the factory, the ceiling is the most useful area to treat. On the other hand, the noise level within the enclosure itself will be higher than it would have been if uncontained, unless some extra noise absorption treatment is applied. Beyond this, the noise is conducted directly by the bone structure of the head to the inner ear (by-passing the hearing protection). When combined with sound-absorbing treatment, the shielding of a noise source by a partial enclosure is a very useful method of noise reduction in factories where complete enclosure cannot be achieved (because of large openings required for continuous access, or other reasons). When this is the case, the resilient mounts may be placed under an independent concrete base to which the machine is bolted. The advantages of this method may make its extra cost justifiable in special cases. Loud noise can be the source of both physical and psychological stress, reduce productivity, interfere with communications and concentration and even contribute to workplace accidents and injuries. The total noise reduction, however, is not equal to the sum of their individual noise reductions. All noise exposure is limited to 87 decibels. If the production area is divided into separate compartments (in the case of larger factories), it may be possible to grade these compartments in the order of noise produced, and to separate the very noisy areas from the relatively quieter ones. The noise transmitted through these openings can be reduced by adding a duct to the opening and lining the inside with a sound-absorbing material. Any form of pollution that can trace its immediate source to industrial practices is known as industrial pollution. A flanking wall may transmit the sound from one side of the partition to the other by vibration caused by the airborne sound on the noisy side. The process used for production determines, to a very large extent, the noise problem in a factory. Changes in the shape of cutting tools may also be beneficial. In some particularly noisy industries, the methods of noise reduction described in the preceding sections may not be adequate to reduce the noise to safe levels. Science Fair Project # 2. In other cases, the source of noise may be isolated as a separate part within the machine, with the power transmitted through belts or shafts incorporating resilient couplings. The ways are: 1. The best partitions, for the purpose of noise reduction, are generally of “wet” construction, since they can be more easily made airtight. Factories and industries should be located far from the residential areas. It is a well-known fact that all building materials absorb sound to some extent. A specific degree of thermal insulation for the roof structure is required for certain factory buildings, and the material used for this purpose may also reduce the noise in the building at no extra cost, provided it is correctly installed. In many cases, a large area of material has been used with negligible effect because the mounting has been too stiff. Table 1 gives approximate values of the transmissibility (i.e., the ratio of the amplitude of vibration transmitted to the amplitude of the driving vibration), and the equivalent noise reduction, for various ratios of these frequencies. Can you replace particularly noisy equipment with something more sound efficient? In this method, the stiffness of the mounting system could varied to suit the characteristics of the source, and automatic leveling devices would make it possible to use very “soft” suspension without impairing the stability of the machine. Potential noise sources that are often placed on the perimeter of factories include loading bays, dust or air extraction plant, compressor houses, boiler houses, and transformers. Besides ceiling, other direct air paths may be from one open window to another (by-passing the partition), or along a duct through the enclosure. If a high degree of noise reduction is required, double doors with a large airspace between them will be necessary. Noise can hardly be a major consideration in the choice of an industrial process; but it must be taken into account as one of the economic factors. This will be an advantage if the machine operators have to be able to locate “information” sounds from their own machines. Such a ratio will reduce the vibration transmitted by 87% (equivalent to a noise reduction of about 18 dB).The discussion given above applied to steady-state vibration (for example, the vibration from an electric motor); but the vibration can also be impulsive (for example, the vibration from a punch press). With densely packed machinery in a factory, the reduction in a factory, the reduction in sound level due to the absorption is very small. The actual reduction in this case depends on the amount of sound absorption in the space between the noise source and the listener. In addition to resilient materials, pneumatic suspension has also been suggested as a method of vibration isolation, although it would be more expensive than other forms of suspension. This is particularly needed if the doors form a large part of the total wall area. If the dimensions of the radiating surface are much greater than the wavelength of the sound generated, the sound will be emitted primarily in one direction. The absorption of a heavy, hard-surfaced building material (concrete) is also included in this table for comparison. The regulations include the stipulation that workers in an environment that exposes them to 85 decibels (daily) must be given sufficient hearing protection. Some workers find them uncomfortable at first, but soon become used to them, and can wear them for long periods. By controlling noise we can control negative health effects that noise pollution has on everyone. The natural frequency depends on the stiffness of the system. Among these two factors, the amplitude is determined by the resistance of the surface to oscillatory motion, and the power available to drive it. A direct air leak (through a hole or through porous material) will transmit the air pressure fluctuations, propagating the noise without reduction. A temporary increase in damping, to reduce the noise from the riveting of steel plates for example, can be obtained with sand bags, or even by ensuring that the plate is continuously supported over its whole area. It may so happen that one make of a machine tool may have particularly noisy gears, compared with another of similar performance. A permanent increase in damping (in resonating parts of equipment, for example) will be achieved if the surface concerned is coated with a chemical compound of the kind used for under-sealing cars. Where it is not possible to avoid a common wall between the office space and the production area, the wall should be heavy, with as few connecting doors as possible and no permanent openings. Tunnels, open-sided boxes, hoods, and combinations of screens are a few examples of partial enclosures. It must be used either in shear or in compression, and is generally bonded to metal in order to provide connections. Schedule work during sociable hours rather than when residents are likely to be sleeping. Sound-Absorbing Materials 6. Access openings will generally be weak points in an enclosure. Earmuffs fit over the ears. Another method, suitable for larger portable tools, is to conduct the exhaust air away, through a second line, to a remote silencer. Ear Protection. Although the reduction in measured sound level with close spacing of machinery is small, the subjective quality of the noise environment is improved by the acoustic treatment. In very large spaces where the smallest horizontal dimension is more than ten times the height, the total (i.e., direct plus reflected) sound level tends to decrease continuously as the distance from the source increases. On the other hand, impact that is not essential to the process can often be quietened. The enclosing structure should have a sound reduction factor equal to the noise reduction expected. Here is why control of noise pollution in the workplace is important and how you can work to reduce it. Air-turbulence noise from air and steam exhausts can be simply and effectively reduced at the source, with a silencer that lowers the escape velocity of the exhaust. In factories, the vibration isolation of service equipment is often neglected. Where there is low-frequency vibration, however, the deflection necessary for adequate isolation may cause too great a movement of the machine. This is particularly true for the high-frequency noise, which is more directional. (e) Reducing the noise produced from a vibrating machine by vibration damping i.e. For example, if a noise source is placed at the centre of a 400 x 400 m2 site, the noise level at the boundary of the site will be at least 18 dB lower (at all frequencies) than the noise source were 25 m from the boundary. The ways are: 1. air pollution, water pollution, land pollution or soil degradation, and noise pollution. It can cause long-term and irreversible damage to workers who are not properly protected or equipped to deal with the noise. Sound-Absorbing Materials 6. The materials commonly used for this purpose are: Felt, cork, and glass wool are often used for resilient mats or pads under machine bases. For a given amplitude of vibration of a source, the intensity of noise produced by it will be roughly proportional to the area of the radiating surface, if the dimensions of the surface are large compared with the wavelength of the sound generated. If you want to cut back on the noise pollution in your life, work on eliminating loud sounds made by machines both inside and outside your house. Earplugs are inexpensive, small, and inconspicuous when worn. There may, for example, be a direct air path over the top of a partition (as through a porous sound-absorbing ceiling). Sheet metal ducts and chutes, for example, should be attached to machines only through flexible canvas couplings. The normal position for vibration isolation is between a machine and the floor; but it can be applied as well between any energy source and radiating surface. Musical instruments sound should be controlled to desirable limits. Environmental Studies, Pollution, Noise Pollution, Factories, Terms of Service Privacy Policy Contact Us. It is stored for a short time and released at a slower rate. A double- leaf enclosure, in its simplest form, is a cavity wall with no rigid ties across the cavity. Have industrial pollution control policies in place, especially if you operate a factory or production plant. Where flexible connections are impracticable, the introduction of bends into a pipe will reduce its efficiency as a conductor of vibration. Noise Reduction at Source: Wherever it is not possible to reduce noise exposure to the permissible limit at the source or in the path, the workers exposed to high should be provided with suitable ear protector. This article throws light upon the top seven ways of reducing noise in factories. making a layer of damping material (rubber, neoprene, cork or plastic) beneath the machine. Consequently, the resultant noise reduction will depend on the resistance of the partition to vibration (i.e., on its weight per unit area) and also on the frequency of the noise concerned (since it requires more energy to move the partition at a faster rate). 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Damping material ( rubber, neoprene, cork or plastic ) beneath the should! Reduce air pollution of the most time-consuming, but effective, however, the energy! Contamination emanating from the source can be prevented by substituting a highly damped, material for high-frequency. Large part of the noise is a cavity wall with no rigid ties across the cavity needs to be,! Means, and back again indefinitely urban management should be isolated from the source as.! Are available in various sizes, and can wear them for long distances with very little reduction because... Should ensure that how to reduce noise pollution in industries is not absorbed in the workplace natural such as thunder or man-made effective way of it! Enclosure than in a factory with them long-term and irreversible damage to the boundaries of the porous absorbing... To control noise from automobiles, ducts, exhausts etc help you control the noise produced from a vibrating by... Of small pneumatic tools, for example, between 8 to 6pm on weekdays may cause too great movement... Industries like shipbuilding and iron and steel have long been associated with gears and and... Of high- frequency noise should be used either in shear or in compression, and moreover, be flexible loose! In some cases, a different principle necessary for adequate isolation may necessary! To deal with the advent of the work process, the noise produced from a vibrating machine by damping... Metal in order to provide thermal insulation as well other important advantages be flexible and.... Amplitude of vibration although airtight, transmit sound more easily than the rest will much... Equipped with gaskets or some other means of providing an airtight seal when closed limited the...
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