ITS will participate in the supply and installation of large soundproof gates at a high-tech industrial site in Western Europe. This involves equipping the openings used for maintenance operations in a large building housing six very high-capacity compressors, in order to limit the sound pressure level outside the building and comply with regulatory requirements:
- European Directive 2003/10/EC concerning the minimum health and safety requirements regarding the exposure of workers to the risks arising from physical agents (noise) is a reference document, fixing:
- limit exposure values for workers to noise: exposure level L EX,8h = 87 dB (A) and peak sound pressure pcrête = 200 Pa or 140 dB (C) ref. 20 μPa
- lower exposure values for workers to noise triggering action: exposure level L EX,8h = 80 dB (A) and peak sound pressure pcrête = 112 Pa or 135 dB (C) ref. 20 μPa
- higher exposure values for workers to noise triggering action: exposure level L EX,8h = 85 dB (A) and peak sound pressure pcrête = 140 Pa or 137 dB (C) ref. 20 μPa
- based on French regulations, a distinction must be made between the daytime period (7:00 a.m. to 10:00 p.m. except Sundays and public holidays) and the nighttime period (10:00 p.m. to 7:00 a.m. as well as Sundays and public holidays):
- in some cases, a prefectural decree (when it is not ministerial) sets the noise levels not to be exceeded at the property boundary: this is particularly the case for Facilities Classified for the Protection of the Environment (FCPE) e.g. 70 dB(A) during the day and 60 dB(A) at night
- emergence i.e. the difference between the equivalent continuous A-weighted pressure levels of ambient noise (industrial site in operation) and residual noise (in the absence of the industrial site, but measured over the period of operation of the industrial site) is limited in the Regulated Emergence Zones (REZ), which generally include, near the industrial site: homes, building zones and areas occupied by third parties e.g. Public Access Buildings (PAB), other industrial establishments. If the ambient noise level in the REZ (including the industrial site noise) is between 35 dB(A) and 45 dB(A) then the admissible emergence is 6 dB(A) during the day and 4 dB(A) at night. If the ambient noise level in the REZ (including industrial site noise) is greater than 45 dB(A) then the admissible emergence is 5 dB(A) during the day and 3 dB(A) during the night.
- in the case of a Facility Classified for the Protection of the Environment (FCPE), the marked tone, the presence of which is linked to the difference between the sound pressure level in a given 1/3 octave frequency band and the adjacent frequency bands, is considered undesirable if it exceeds 10 dB in the frequency range 50 Hz-315 Hz or 5 dB in the frequency range 400 Hz-8000 Hz
Meeting such objectives is no small feat when the cumulative acoustic power level of the noise sources is around 135 dB(A), and when it is foreseeable that an amplification of sound levels will occur due to the phenomenon of reverberation in an industrial hall with a volume close to 9000 m3.
These soundproof metallic gates must therefore have a very high sound reduction index (around 50 dB for high frequencies) resulting from the limitation of sound transmission both through the door leaves (performance will be based on the use of a special multi-layered acoustic structure) and around the perimeter (airtightness is paramount, including at floor vicinty, and the compression seals devices must be outstanding).
Given the large dimensions of these soundproof gates (5 m wide, 5 m high), design (including structural calculations and the development of flawless assembly techniques) and manufacturing (including strict compliance to dimensional tolerances, squareness, and welding standards) must be carried out with meticulous care and rigorous quality control at every stage (anti-corrosion treatment will be a crucial feature to ensure a long lifespan). What is at stake is the reputation of ITS and its commercial partners for acoustic doorsets, major components - whether they are hinged or sliding, then in horizontal or vertical translation - of quality industrial soundproofing systems, appreciated by a demanding clientele from time immemorial.
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