Noise reduction at source consists in reducing the sound power of a noisy hardware or equipment, by means such as an enclosure (acoustic hood) for a machine, a soundprrofing partition for a noisy area in a workshop for example, a silencer for a ventilation opening (or an suction / outlet / exhausy linked to an industrial process).
Reduction of noise at source by means of sound-absorbing enclosures or partitions
Reducing noise at source by means of soundproofing enclosures or partitions consists in implementing a continuous separation between two spaces:
- the one that contains the noise source (even when there is only one machine or one piece of equipment, the noise source is not always unique - when different organs have significant noise emissions -)
- the one one wants to protect from noise
In practice, noise reduction at source can take quite different forms, in relation to the size that needs to be considered:
- canopies, soundproof casings for small or medium-sized sound sources e.g. pumps, fan housings, small motors (thermal or electric), compressors of limited capacity
- enclosures for machines of all kinds (wood and metal working, cardboard manufacturing, processing of raw materials for the construction sector)
- partitions (between floor and roof e.g.connecting with two opposite walls of a building) for large noisy machines and facilities (e.g. printing presses)
- soundproof containers and buildings for high-power heat engines, high-capacity compressors, combustion turbines
In many cases (in the industrial sector) the noise reduction at source by means of enclosures or sound-absorbing partitions can be achieved using metal constructions:
- with a frame/a framework
- with multilayer acoustic insulation panels having properties both in terms of sound reduction (i.e. opposing the transmission of noise) and in terms of sound absorption (i.e. preventing the sound level amplification invloved - otherwise - by the presence of an obstacle to the propagation of noise in a free field); they can advantageously be modular and removable (to allow maintenance operations)
- with acoustic doorsets to allow access (for people - on foot or motorized - or for equipment)
- with sound-reducing glass frames to allow visibility from a space separated by the device for noise reduction at the source to the other
- with noise reduction equipment for ventilation openings which are often necessary
Reduction of noise at source by means of silencers
Reducing noise at source by means of silencers is required in different contexts:
- when the considered fluid is air with a temperature and a pressure close to atmospheric conditions for the ventilation of soundproof enclosures or partitions, for applications - in constructions - related to Heating, Ventilation, Air Conditioning (HVAC)
- for industrial processes involving air condensers (dozens of fans are sometimes to be considered for a single installation), cooling towers (the diameter of the fans can exceed 10 meters), air intakes for engines and turbomachines (the entrance area may exceed 100 square meters)
- when the considered fluid is a combustion gas (i.e. with a very high temperature - which can reach 850°C in the case of special processes, generally between 500°C and 650°C when it comes to thermal engine exhausts or gas turbines -)
- when the considered fluid is an industrial gas possibly very cold (if it is expanded) or very hot (if it is a vaport steam vent)
The operating principle (dissipative i.e. involving a sound-absorbing material, or reactive i.e. with sound reflections induced by the geometry of the internal parts), the design (acoustics, aeraulics), the construction (choice of steels, resistance to pressure) must be studied on a case-by-case basis and can lead to devices that vary greatly in size, shape and performance.
What ITS offers in terms of noise reduction at source
What ITS offers in terms of noise reduction at source (depending on the case):
- an on-site diagnosis with sonometric measurements
- an engineering mission for the research and development of solutions (such design office work may require calculations of sound propagation and impact and sizing in terms of acoustics and aeraulics)
- noise reduction hardware:
- components: silencing materials, industrial soundproofing panels and acoustical claddings, silencers of all kinds
- systems: soundproof canopies, sound enclosures, complete noise attenuating buildings
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