The noise study is an activity conducted for the analysis, modelling and simulation of an industrial plant. Noise study has the scope to identify and acoustically model these equipment’s – namely sources – and analyse the effects produced by relevant noise sources, on the environment and on plant personnel.
References
| EN ISO 11200 | Guidelines for the use of basic standards for determination of emission sound pressure levels at a works station and at other specified positions |
| EN ISO 11203 | Noise emitted by machinery and equipment - determination of emission sound pressure levels at a work station and at other specified positions from the sound power level |
| BS 4142 | Method for rating industrial noise affecting mixed residential and industrial areas |
| ISO 15664 | Acoustics – Noise control design procedures for open plant |
| ISO 15665 | Acoustics – Acoustic insulation for pipes, valves and flanges |
| ISO 11546-2 | Determination of sound insulation performance of enclosures - Measurements in situ |
| ISO 9613-2 | Attenuation of sound during propagation outdoors - General method of calculation |
| ISO 9614-1 | Determination of sound power levels of noise sources using sound intensity Measurement at discrete points |
| ISO 9614-2 | Determination of sound power levels of noise sources using sound intensity Measurement by scanning |
| EEMUA 140 | Noise procedure specification |
| EEMUA 142 | Acoustic Insulation of pipes, valves and flanges |
General
The plant Noise study is developed thought the following 5 main steps:
- Data collection
- Modelling/simulation
- Calculation
- Result analysis
- Document preparation
The following flow-chart identify the main workflow between each phase, providing evidence how Iteration are handled in case of non-compliance.
Modelling
The modelling procedure requires studying of the noise emission sources at the following perspective:
- Acoustical (acoustic emission),
- Geometrical (dimensions) and
- Physical (structure, sub-units).
Calculation
Once the simulation scenario has been defined, it is necessary to choose the calculation algorithm to be used (i.e. the set of equations used by the program to evaluate propagation of the acoustic waves). Standard ISO 9613 shall be used when no contractual-legislative requirements define otherwise.
Calculation can be carried out for all the analysis area (i.e. production of noise isopleths maps) or for defined points which usually correspond to sensible receptors.
Result Analysis
The simulation results are compared against the permissible limits defined by national regulatory/ legislative or contractual requirements. The analysis includes verification of the compliance with aforementioned limits and/or, where such limits are not complied with, the definition of the potential mitigation actions.
Document Preparation
The noise study is finalized with the preparation of a noise study report.
The Noise Study should be structured as follows:
- Introduction with a brief description of the purpose and objectives of the study
- References and abbreviations
- The regulatory framework
- Characterization - for the study of environmental impact):
- Pre-existing ambient noise
- Identification of receptors
- Brief description of the model used
- Methodology
- Description of the results and conclusions
- Any mitigation measures;
- List of sources considered spectrum including power output and overall sound pressure;
- Noise maps, noise studies for non-dedicated to an environmental impact study should have more maps of work areas as well as a map of the area surrounding the plant noise situation
In order to estimate the operational noise level, the internationally recognized noise modelling software "SoundPLAN" version 8.1 has been utilized. The propagation methodology adopted, and the equations used within the SoundPLAN model are based on the ISO 9613 ‘Acoustics – Attenuation of Sound during Propagation Outdoors’ (ISO, 1996)
SoundPLAN has been developed by Braunstein & Berndt GmbH in Germany, and belongs to the class of sophisticated provisional models, based the technique of the Ray Tracing Inverted (from the receivers), that allow to simulate the propagation of the noise in complex source situations and orography.
The model allows calculating the sound levels due to various types of industrial sources and introduces its own algorithms for the calculation of the ground effect, the absorption and the other phenomena involved. The equations used in order to estimate the propagation of the sound waves, in particular for sources of industrial type, are those described in the International Standard ISO 9613.