18-06-2014, 10:44 AM
A
PAPER PRESENTATION
ON
Noise pollution in Textile Industry
EXTIRPATING NOISE FROM IMAGES.doc (Size: 483.5 KB / Downloads: 9)
ABSTRACT
One of the major stresses with which industrial workers must cope is excessive noise exposure. Operation of textile machines is one of the occupations that carry a particularly high risk of hearing. Noise induced hearing loss is an irreversible and incurable disease. Prevention is of primary importance. Since the disease develops slowly over the years and since the first signs readily detected by simple audiometric examinations, it can be said that the basic principle for medical prevention is the periodic audiometric examinations. Clearly, this basic medical practice should be followed up by a series of environmental and organizational preventive measures required to remove the affected worker from the hazardous working environment.
Noise at work can cause hearing loss which can be temporary or permanent. People often experience temporary deafness after leaving a noisy place. Although hearing recovers within a few hours, this should not be ignored. It is a sign that if you continue to be exposed to the noise your hearing could be permanently damaged. Permanent hearing damage can be caused immediately by sudden, extremely loud, explosive noises, e.g. from guns or cartridge operated machines.
But hearing loss is usually gradual because of prolonged exposure to noise. It may only be when damage caused by noise over the years combines with hearing loss due to ageing that people realize how deaf they have become. This may mean their family complains about the television being too loud, they cannot keep up with conversations in a group, or they have trouble using the telephone. Eventually everything becomes muffled and people find it difficult to catch sounds like ‘t’, ‘d’ and ‘s’, so they confuse similar words.
Hearing loss is not the only problem. People may develop tinnitus (ringing, whistling, buzzing or humming in the ears), a distressing condition which can lead to disturbed sleep.
Introduction
Physically, there is no difference between sound and noise. Sound is a sensory perception and noise corresponds to undesired sound. By extension, noise is any unwarranted disturbance within a useful frequency band. Noise is present in every human activity, and when assessing its impact on human well-being it is usually classified either as occupational noise (i.e. noise in the workplace), or as environmental noise, which includes noise in all other settings, whether at the community, residential, or domestic level (e.g. traffic, playgrounds, sports, music).
Fundamentals of noise
Amplitude
Loudness of a sound depends on the amplitude of the fluctuations above and below atmospheric pressure associated with a particular sound wave. The mean value of the alternating positive and negative pressure fluctuations is the static atmospheric pressure, not a useful descriptor of sound. However, the effective magnitude of the sound pressure in a sound wave can be expressed by the “root-mean-square” (rams) of the oscillating pressure measured in Pascals.
The quietest sound that can be heard by most humans, the “threshold of hearing," is a sound pressure of about 20 µPascal, and the loudest sounds typically found in our environment range up to 20 million µPascal. Because of the difficulty in dealing with such an extreme range of numbers, acousticians use a compressed scale based on logarithms of the ratios of the sound energy contained in the wave related to the square of “sound pressure level” in decibels (dB).
Decibel Addition
The combination of two or more sound pressure levels at a single location involves ‘decibel addition’ or the addition of logarithmic quantities. The quantities that are added are the sound energies ( p2rms ). For example, a doubling of identical sound sources results in a 3 dB increase, since:
Hearing loss
Noise at work can cause hearing loss which can be temporary or permanent. People often experience temporary deafness after leaving a noisy place. Although hearing recovers within a few hours, this should not be ignored. It is a sign that if you continue to be exposed to the noise your hearing could be permanently damaged. Permanent hearing damage can be caused immediately by sudden, extremely loud, explosive noises, e.g. from guns or cartridge operated machines.
But hearing loss is usually gradual because of prolonged exposure to noise. It may only be when damage caused by noise over the years combines with hearing loss due to ageing that people realize how deaf they have become. This may mean their family complains about the television being too loud, they cannot keep up with conversations in a group, or they have trouble using the telephone. Eventually everything becomes muffled and people find it difficult to catch sounds like ‘t’, ‘d’ and ‘s’, so they confuse similar words.
Hearing loss is not the only problem. People may develop tinnitus (ringing, whistling, buzzing or humming in the ears), a distressing condition which can lead to disturbed sleep.
Conclusion
To understand for noise control it is experienced that the controlling systems not only reduce the noise at source to acceptable levels but also energy consumption in some extent and at the same time leads to a better design of machines too
Polymeric gear arrangement or polymeric spindle consumes less energy compare to metallic one for same rpm
Noise control can be achieved by two ways machine and passive ways
By replacing materials it is possible to reduce vibration and friction in situ of noisy parts
For passive control, different process such as using damping barrier and absorption materials can be used