Najah Engineering Consultants LLC

Industrial Noise Control Services


Industrial Noise Control Studies

Study different equipment noise and recommend suitable noise insulation. This include diesel generators, gas turbines, compressors, pumps, fans, chillers, factory machineries, traffic noise,...etc. Our evaluations and recommended solutions meet general guidelines and practices of international standards and nroise laboratories such as ASTM E477, ASTM E90, ISO 140, ISO 7235, 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). All our studies are done in accordance with the known international standards like: ISO 6798, ISO 8528-10, ISO 3746,..

NEC Acostix ™ Software

NEC Acostix software is a programmable spreadsheet based software developed by Najah Engineering Consultants to help design engineers, consulting engineers and manufacturers to design acoustic enclosures, noise barriers, and 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. Upon request, the software can be customized to suit different customer's business requirements. Click to see more details.

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 airflow 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 airflow 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 airway velocity. Typically, this should not exceed 120 Pa diesel generators and for most of the systems.

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