In a metal forming workshop, a press is a very powerful noise source potentially causing sound nuisance for the personnel operating in the vicinity (in production halls) and sometimes also for the neighborhood (more occasionally). It is often necessary to use in such cases a high-tech soundproofing equipment (sound enclosure) to ensure the conformity of the facility with respect to the legislation on noise in workplaces and sometimes also with respect to the regulations in terms of fight against domestic noise:
- Directive 2003/10/EC of the European Parliament and of the Council of February 6, 2003 concerns the minimum health and safety requirements relating to the exposure of workers to the risks due to physical agents (noise), setting limits for the levels of daily exposure to noise and peak sound pressure: exposure limit values: LEX, 8h = 87 dB (A) and ρpeak = 200 Pa respectively; higher exposure values triggering the action: LEX, 8h = 85 dB (A) and ρpeak = 140 Pa respectively; lower exposure values triggering the action: LEX, 8h = 80 dB (A) and ρpeak = 112 Pa respectively
- in France, the public health code (article R. 1336-7) sets values not to exceed for the emergence linked to the difference, at a specified location - in a Regulated Emergence Zone (REZ) - between the measured sound pressure levels respectively during operation and when the plant is shut down (the night situation being almost always - all other things being equal as regards the operating conditions - more problematic than that observable during the day: the admissible emergence varies, in France , from 3 dB (A) to 6 dB (A) according to the time schedule, but also according to the day of the week and according to the ambient noise value and this does not only concern Installations Classified for the Protection of the Environment - in short ICPE - but all industrial sites in reality); elsewhere in the world, although local regulations differ, taking the neighborhood into account in terms of acoustics is also often required
ITS will participate in the construction of a sound enclosure to reduce the noise of a press near Aix les Bains in the county of Savoie in the region Rhône Alpes (France).
This soundproofing device will offer a sound reduction particularly important at medium and high frequency where the maximum of the noise emission of the enclosed noisy equipments is, requiring a specific design and a specific construction of the partitions for this enclosure for a press.
Indeed, two fundamental functionalities are required in terms of acoustics:
- the limitation of sound transmission through walls (characterized by its sound reduction index - which must not be less, overall, with respect to a pink noise spectrum [1], than 30 dBA to ordinarily reduce the noise of a press)
- the sound absorption (characterized by its sound absorption coefficient - which should be as close as possible to 100% at medium and high frequencies -) to avoid an increase in the sound pressure level inside the enclosure (due to the reflections of sound waves), which would otherwise, then result - all things being equal as to the acoustic attenuation - in an increase, obviously undesirable, of the sound level outside (the same one that one seeks to minimize).
The use of modular metal industrial sound insulation panels will be suitable for such a construction of a sound enclosure to reduce the noise of a press.
Related features such as visibility for the operation of the machines, access for maintenance work, disassembly of some subsets of the soundproofing equipments ... will be integrated according to the needs, requiring the multidisciplinary skills that the human ressource of ITS and of its commercial partners has for such industrial soundproofing realizations.
The quality of design and manufacture will give this hardware intending to allow a protection against noise at work a solid strength, and ipso facto, a great durability.
[1] i.e. with the same sound power level in each 1/1 octave frequency band