Noise controls

Members consist of noise-control professionals who develop engineering solutions to environmental noise problems. 

National Organization to Insure a Sound-Controlled Environment 

They seek to eliminate jet noise from the environment by confronting legislatures to ensure that rules are being followed. 

This company manufactures a device that measures the various energies of sounds on several levels. 

CEL manufactures noise dosimeters that can be worn by personnel to obtain individual exposure samples. 

Distance is a major factor in reducing nuisance noise and suitable spacing should be considered in the plant initial layout. The acceptable amount of noise generation should be specified on the purchase order for the equipment. Where sound levels cannot be alleviated by purchasing a different make of equipment, sound attenuation devices should be fitted (i.e., enclosures) as an alternative. 

Whenever ambient noise levels are above emergency alarm signals or tones, flashing lights or beacons should be considered that are visible in all portions of the affected area. The color of flashing lights should be consistent with the safety warning colors adopted at the facility. 

Coal preparation plants invariably contain various types of active machinery, in addition to large throughput tonnages of free-falling solids, and have long been recognized as presenting a serious noise problem. Most of the noise control measures may be classified broadly into measures that 

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L. L. Beranek, Noise and Vibration Control, Institute of Noise Control Engineering, Cambridge, Mass., 1988. 

A. Thumaim and R. Miller, Fundamentals of Noise Control Engineering, 2nd ed.. The Fairmont Press, Inc., Lilbum, Ga., 1990. 

Ferroelectric—polymer composite devices have been developed for large-area transducers, active noise control, and medical imaging appHcations. North American Philips, Hewlett-Packard, and Toshiba make composite medical imaging probes for in-house use. Krautkramer Branson Co. produces the same purpose composite transducer for the open market. NTK Technical Ceramics and Mitsubishi Petrochemical market ferroelectric—polymer composite materials (108) for various device appHcations, such as a towed array hydrophone and robotic use. Whereas the composite market is growing with the invention of new devices, total unit volume and doUar amounts are small compared to the ferroelectric capacitor and ferroelectric—piezoelectric ceramic markets (see Medical imaging technology). 

R. D. Berendt and G. E. Winder, A Guide to Airborne, Impact, and Structure Rome Noise Control in Multifamily Dwellings, U.S. Department of Housing and Urban Development, Washington, D.C., 1963. 

Catalog of STC andllC Ratings for Wall andEloorj Ceiling Assemblies, Office of Noise Control, California Department of Health Services, Berkeley, Calif., 1984. R. S. Jones, Noise and Vibration Control in Buildings, McGraw-HiU Book Co., Inc., New York, 1984. 

D. A. Bies and C. H. Hansen, Engineering Noise Control Theoy and Practice, Unwin Hyman Ltd., London, 1988. 

Compendium of Materialsfor Noise Control, HEW (NIOSH) pubHcation 75-165, HEW, Washington, D.C., June 1975. 

C. M. Harris, ed.. Noise Control in Buildings, McGraw-HiU Book Co., Inc., New York, 1994. 

Clean Air Act and its amendments ia 1970, 1977, and 1990 1967 Air Quahty Standards and National Air Pollution Acts and 1970 National Environmental PoHcy Act) (2) better waste disposal practices (1965 SoHd Waste Disposal Act 1976 Resource Conservation and Recovery Act) (see Wastes, industrial Waste treatment, hazardous wastes) (i) reduced noise levels (1972 Noise Control Act) (4) improved control of the manufacture and use of toxic materials (1976 Toxic Substances Control Act) and (5) assignment of responsibiUty to manufacturers for product safety (1972 Consumer Product Safety Act) (15,16). 

Noise Control Sound is a fluctuation of air pressure that can be detected by the human ear. Sound travels through any fluid (e.g., the air) as a compression/expansion wave. This wave travels radially outward in all directions from the sound source. The pressure wave induces an oscillating motion in the transmitting medium that is superimposed on any other net motion it may have. These waves are reflec ted, refracted, scattered, and absorbed as they encounter solid objects. Sound is transmitted through sohds in a complex array of types of elastic waves. Sound is charac terized by its amplitude, frequency, phase, and direction of propagation. 

There are two approaches to fluid-generated noise control—source or path treatment. Path treatment means absorbing or blocking the transmission of noise after it has been created. The pipe itself is a barrier. The sound pressure level inside a standard schedule pipe is roughly 40-60 dB higher than on the outside. Thicker walled pipe reduces levels some at more, and adding acoustical insulation on the outside of the pipe reduces ambient levels up to 10 dB per inch of thickness. Since noise propagates relatively unimpeded inside the... 

At the fan-tip speeds required for economical performance, a large amount of noise is produced. The predominant source of noise is vortex shedding at the traihug edge of the fan blade. Noise control of aircooled exchangers is required oy the Occupational Safety and Health... 

Noise control is worth mentioning. The turboexpander and axial compressors are noise producers and consideration must be given to the need for providing noise abatement. Silencers on vents and noise insulation housings on machines should be considered and have been proven effective. 

Power Supply Cookbook, Second Edition has been updated with the latest advances in the field of efficient power conversion. Efficiencies of between 80 to 95 percent are now possible using these new techniques. The major losses within the switching power supply and the modern techniques to reduce them are discussed at length. These include synchronous rectification, lossless snubbers, and active clamps. The information on methods of control, noise control, and optimum printed circuit board layout has also been updated. 

The elevated flare shall meet the noise level as specified in the Noise Control Specification ME-0- JD002. 

Sharland, I. (1972). Woods Practical Guide to Noise Control. Woods of Colchester, l.td. 

As a side benefit, on electric arc furnaces the enclosure offers a great potential for noise control. 

Most louver systems have a pitch between 30 mm and 100 mm. Where noise control is required, louvers can be supplied either in the form of acoustic louver with a pitch of 300 mm and acoustic material in the louver blade or as standard louver with an attenuator section behind it. A bird or insect guard (as applicable) is normally mounted behind the louver. 

This necessitates plant capable of control of temperature by being able to add or subtract heat from the air and control of humidity by being able to add or subtract moisture. The system also comprises fan(s), filtration, and a distribution system and may include noise control. Other terms such as cooling or comfort cooling may be met and these can be taken to mean an ability to lower the temperature of the air by refrigeration but without full control of humidity. Moisture may be removed as an incidental characteristic of the cooling coil. The term air conditioning is sometimes used where control of humidity is not included. It is essential to employ clear specifications of performance. 

Before attempting noise control it is important to consider the nature of the problem ... 

There are many proprietary systems available for controlling noise and it is easy to become blinded in one s approach to noise control. 

If the decision is made to retain the original machine the design of the noise-control devices to be employed should be considered. These may affect ... 

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