Acoustic enclosures limit the level of noise emitted from a source and perceived by the recipient. One of two methods may be used The source is screened from the recipient or The recipient is screened from the source In general, it is the better course to treat any noise as close to the source as is possible by an acoustic enclosure. If this cannot be done for practical or economic reasons the recipient may be protected by a cabin in which the important aspects of adequate vision, sufficient illumination and ventilation have been incorporated.
Principle of operation
The noise attenuation of the walls and roof of the space-enclosure is influenced by the noise spectrum of the emissions, the form and materials of construction and the quality of the construction. For example, the absorbent material thickness influences the attenuation of the middle and higher frequencies. Increasing the mass present by thicker or heavier panels improves lower frequency treatment. The reduction in noise afforded by a Q.E. International B.V. acoustic enclosure is the measured difference between the noise level within the enclosure and the noise level outside the enclosure and this is, mainly, in the physical size of the enclosure and the space in which it stands.
The enclosure comprises one or several panels combined to form a stable structure. Each panel has: An exterior plate formed from aluminum or steel plate. The selection being dependant on the mass and noise attenuation required.
The attenuation in the diffuser is achieved in the following steps:
- Type of diesel or gas motor (in-line or V-)
- Noise entering the diffuser is partially reflected. The proportions of the diffuser determine this effect.
- The openings in the diffuser force the production of small gas jets which mutually interfere so attenuating noise further
- The noise spectrum is altered. Low frequency noise being transformed to the higher frequencies that are more efficiently impeded by the pipe wall.
An anti-resonance layer attached to the exterior plate by an adhesive bond. This reduces considerably the tendency of the exterior plate to exhibit low frequency vibration and this contributes to the plate mass so enhancing noise attenuation. Mechanical stiffening of the plate for structural stability and improved anti-resonance. Acoustic absorbent material with a dual purpose: To absorb noise and to prevent additive effects within the enclosure owing to multiple noise reflections. A protection film to prevent ingress of moisture or oil vapour into the absorbent material. An inner plate that is perforated providing added protection and support to the absorbent material.
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Noise Attenuating Glass Windows |
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In order to provide adequate vision of the production process windows can be incorporated into the design. Single panes of glass are often insufficient because of the ‘coincidence’ effect where the vibration response of the glass is coincident with a frequency emitted by the process and, then, the noise reduction at that frequency is almost zero. The frequency at which this happens depends upon the glass thickness and the angle at which the noise strikes the glass. The design of windows, particularly large window areas, requires great care in the details of glass responses.
Egonometry and custom design
Enclosure of a machine or process automatically implies restricted access there and it is essential that, in the design stage, focused attention to this is made. After all, the success of the noise isolation will depend upon the daily habits of the personnel for the benefit of whom the protective measures have been taken. Q.E. International B.V. pays great attention to these ergonometric aspects. The areas of wall openings, inspection access, window and door openings are decided in close consultation with the User.
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Ventilation |
In enclosures and in cabins consideration must be given to moisture and heat generation so that each unit must be adequately ventilated – either by natural or by forced circulation. Excessive heat can be combated by a cooling installation or air conditioning installation
Integral approach and optimal result
To arrive at the best solution Q.E. International B.V. adopts the following procedure:
Definition of the noise problem
Measurement of the noise at the site. Survey of the noise abatement norms and regulations as well as Health and Safety requirements.
Complete design
To comply with all of the requirements the noise treatment design is completed. Q.E. International B.V. your partner in industrial noise suppression. With more than 40 years of experience in industrial noise abatement Q.E. International B.V. has demonstrated itself to its satisfied and trusted clientele to be the partner of choice in the solution of industrial noise problems. Q.E. International B.V. has specialized in the design, fabrication, supply and erection of acoustic enclosures, containers, cabins, walls, baffle silencers, ventilation grids, noise isolation doors and screens. Q.E. International B.V. can also service your space-noise abatement needs. In addition to carbon steel components we are also able to provide items in steel and aluminum alloys and industrial plastics. Fabrication of all units is done, under our continuing supervision, at carefully selected sites employing specialist welders and artisans, sites that offer the most economical construction. Erection, using specialist teams, may be arranged.
Delivery is complete when final noise measurements confirm the contractual requirements.
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