Industrial Noise Control Studies Study different equipment noise and recommend suitable noise insulation. This include diesel generators, gas turbines, compressors, pumps, fans, chillers, facory machineries, traffic noise,...etc. Our evaluations and recommended solutions meet general guidelines and pratices of international standards and noise laboratories such as ASTM E90, ISO 140, Sound Research Laboratory (SRL) and others. Our services extend to design or verifying others design to meet the specified noise rating (NR) or noise criteria (NC).

Acoustic Walls and Noise Barriers: We design and verify the design of walls and barries used to block noise from different sources. Walls can be used as part of acoustic enclosures or buildings. Determining the sound reduction index (SRI) of the wall is a major objective to block the noise to meet the specified noise rating or criteria.

Rectangular Air Duct Attenuators: Attenuators are inserted in the air duct systems to attenuate the sound level to meet the specified noise rating or criteria. Sound attenuators attenuate the sound but they cause considerable pressure drop to the air flowing through them. This pressure drop must be carefully and precisely calculated to ensure the duct air flow is smooth and in the same time the sound is attenuated. The attenuators have many design parameters such as the number of splitters in the duct, the thickness of the splitters, the air gap between them, the aperture height and width, the attenuator duct length, type and density of acoustic filling used in the splitters, perforation configuration and air flow rate. When air flows in the ducts it generates noise which could also be considerable if the air flow speed is high. Attenuators are acoustically sized using insertion loss (IL) measured in dB across the octave band frequencies. Aerodynamically it is sized in terms of pressure drop at certain air velocity. Typically this should not exceed 100 Pa for most of the systems.

Acoustic Louvers: Acoustic louvers are used in buildings to handle large volume of air flow inlet or discharge while keeping the noise within the specified noise rating or criteria. Louvers are less deep than attenuators and they are cosmetically more suitable for residential and commercial buildings. Louvers can have different shapes. The shape of the louvers affect the air flow and in the same time dictates the sound transmission loss (STL). The STL is normally used to indicate the louvers acoustical performance. Acoustical treatment of louvers can include acoustic materials filling covered by perforated steel or aluminum sheet. The louvers should be designed to achieve the required STL and in the same time to allow the volume of air to flow without exceeding the maximum allowable pressure drop.

Exhaust Systems Silencing: This includes the silencing of high speed exhaust gases with pulsating noise. Diesel generators exhaust silencers are good example of these silencers. Silencers are acoustically designated by what is known as grade. Grades can be found to be from industrial grade with only 10-15 dB attenuation up to hospital grade silencers with up to 50-55 dB attenuation. The silencers are also sized with respect to their exhaust flow capability. This is designated in terms of silencer pipe diameter. To elect the suitable silencer you should know the engine exhaust noise level (exhaust noise spectrum) and you should have noise rating or criteria which you should not exceed. NEC can assist you to calculate the suitable silencers for the system.

Acostix 2010 Acostix 2010 is a spread sheet based software developed by Najah Engineering Consultants to help design engineers, consulting engineers and manufacturers to design acoustic enclosures, noise barriers, acoustical rooms and do various acoustics calculations. It also helps them verify if existing designs can conform to the noise rating specified by the customers. Read more...   Subscribe to our newsletter

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