Combined sound attenuator and jet hood [Type SONEX2]

Application area

The Sonex unit is specially designed to reduce noise from ventilation outlets by being a combination of an exhaust hood and a sound attenuator. By "jetting" exhaust air upwards through the unit and mixing it into the atmosphere at the top of the unit, the noise impact on the deck floor is low because of the advantage of leading the noise in an upward direction. Moreover, the Sonex is an absorptive attenuator using mineral wool as the insulation material, which is non-toxic and non-combustible.

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Materials and dimensions

Standard product range is from nominal diameter Ø250 mm up to and including diameter Ø1250 mm. Depending on the size, the design of the exhaust hood reduces the noise level by 15-20 dB, with a maximum recommended duct velocity of 7-8 m/s. All details of the combined sound attenuator exhaust hood are made from AISI316L stainless steel.

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Noise data

Noise data and pressure drop values are based on the following standards:

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- ISO 7235:2003: Acoustic measurement for duct insulators, insertion loss, current level noise and total pressure loss

- ISO 5135:1997: Determination of sound power levels of noise from air terminal units, dampers and valves by measurement in reverberation rooms

- ISO 3741:1999: Determination of sound power levels of noise sources - Precision methods for broadband noise in reverberation rooms

- ISO 5221:1984: Rules for methods of measuring airflow velocity in air-handling ducts

- EN 12238:2001/1: Aerodynamic testing and assessment for mixed flow applications

The sound reduction achieved by the Sonex will depend on the arrangement of the ducting. Measurements performed in laboratory will vary from measurements taken on site, due to factors as structural vibrations, flanking noise, background noise etc. To achieve the best possible results, please contact Nordic Steel for more information about self-generated noise and noise calculations according to your specific needs.