When it does not have to do with heat transfer (conduction, convection, radiation), industrial insulation is related to the limitation of noise emissions from machines or installations involving various industrial processes that share a common characteristic: being noisy.
ITS is a company specializing in industrial insulation, offering diagnostics and solutions against noise (performance in terms of soundproofing is guaranteed).
Industrial insulation against noise: diagnosis
In the context of industrial insulation against noise, a diagnosis is often motivated by regulatory concerns, which are generally two in number.
On the one hand, it is a question of making sure that the workers of the concerned sites are not in a situation of auditory trauma. Therefore, exposure limit values specified in Directive 2003/10/ EC – i.e. a daily noise exposure level of 87 dB (A) or a peak sound pressure level of 140 dB (C) - should in any case be exceeded, much lower values – i.e. a daily noise level of 80 dB (A) or a peak sound pressure level of 135 dB (C) – having to trigger the action by proportionate means.
On the other hand, it is a question of ensuring that there is no noise nuisance for the vicinity of such industrial sites. Therefore, the emergence i.e. the difference between the A-weighted equivalent continuous pressure levels of the ambient noise (establishment in operation) and the residual noise (in the absence of the noise generated by the establishment) in Zones with Regulated Emergence (ZRE) should not exceed the permissible emergence which is 6 dB (A) in the daytime period and 4 dB (A) in the nighttime period if the ambient noise level in the ZREs (including noise from the establishment) is included between 35 dB (A) and 45 dB (A); which is 5 dB (A) in the daytime period and 3 dB (A) in the nighttime period if the ambient noise level in the ZREs (including the noise of the establishment) is greater than 45 dB (A). This is in France, the regulatory constraint set by the decree of 23 January 1997, relating to the limitation of noise emitted into the environment by Establishments Classified for Environmental Protection (ECEP)
When entrusted to ITS, a diagnosis in relation to industrial noise insulation is carried out:
- by a human ressource skilled in physical measurements (specialized in instrumental techniques) for on-site metrology (most often: for the determination of sound levels)
- by an acoustician qualified in building physics (with extensive experience in aeraulics, fluid mechanics, construction technologies) for the analysis of the results of acoustic measurement campaigns, for the comparison of indicators subject to regulations with reference values and for the study of the possibilities of improving the situation, when this is required (if necessary: by carrying out predictive acoustic calculations with software)
Industrial insulation against noise: solutions
Sometimes, it can happen that a diagnosis highlights authorized limits being exceeded, placing the industrialist operating the site at the origin of the disorders in a situation of a legal offense fine, and exposing him to various hazards (pell-mell):
- internally: absenteeism, difficulty in recruiting, lower yields and quality of work, risk of hearing damage, risk of accidents (e.g. when warning signals are not heard)
- wconcerning the neighborhood: recriminations, complaints, administrative sanctions
As a result, soundproofing devices must be considered, which is a separate field of industrial insulation.
Some use a technology being common with that used for the limitation of heat transfers (thermal lagging): the acoustic insulation of pipes, valves and flanges is based on the implementation of insulation systems consisting of a porous layer (e.g. mineral wool) and a metal covering e.g. steel, aluminum which is often reinforced by a damping layer e.g. bitumen, viscoelastic.
A reduction of the noise radiation of such pipe network elements can thus be obtained, the importance of which is related to the envisaged constructive system (nature of the materials, thicknesses) and also to the geometric characteristics of the support: the insertion loss does is not the same for a circular pipe, a rectangular duct or a plate and the characteristic dimensions of the support play an important role (a negative insertion loss is associated with the resonance phenomenon resulting from the installation of the doubling).
The body of some elements e.g. flanges, compensators must be surrounded by a removable cover or by an acoustic enclosure e.g. valves (it is often a construction similar to those of the normal surfaces but mounted on a metallic structure, when it is not realized by means of modular industrial soundproofing panels used for enclosures of other machines and noisy equipment, for the realization of acoustic screens, also called noise barriers or for the realization of industrial soundproof buildings).
The end of piping systems for which industrial insulation must be considered is often equipped with silencers, allowing the discharge of a pressurized fluid into the atmosphere: a perforated element (upstream) possibly multi-staged is completed by a lining dissipative absorbent (downstream) in the form of splitters: the acoustic performance of such vent silencers shall be compatible with the maintenance of service conditions (related to the aerodynamic performance of the devices) appropriate for the facility, with regard to what is required for the processes which are involved.
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