First International Conference on MOLDAVIAN RISKS – FROM ...

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<strong>First</strong> <strong>International</strong> <strong>Conference</strong> on MOLDAVIAN RISKS - FROM GLOBAL TO LOCAL SCALE 16-19 May 2012, Bacau, Romania EXPERIMENTING RIGID AND ELASTIC CLAMPING METHODS OF ACOUSTIC SCREENS Claudia Tomozei, Valentin Nedeff, Mirela Panainte, Gabriela Andrioai “Vasile Alecsandri” University of Bacau, Department of Environmental Engeneering and Mechanical Engeneering Corresponding author: Tomozei Claudia, claudia.tomozei@ub.ro Abstract: Noise transmission in enclosures can be controlled by treating the acoustic enclosures in such a way as to limit inside and outside sound propagation. The industrial noise can be controlled either by eliminating noise generating factors or by using soundproofing materials to attenuate noise on propagation pathways. The attenuation of acoustic wave propagation in industrial environments is a very important issue that may be studied in different environments and may receive different solutions. One way to attenuate sound pressure level/ SPL propagation is by using acoustic screens. This article investigates two methods of noise reduction in industrial enclosures with the help of acoustic screens which are composed of multiple walls. The results of the experiments are charted and presented in the paper. The proposed method consisted in using work variants that presuppose the rigid and elastic clamping of the walls to the metallic frame.The rigid clamping was done by using screws to attach the walls to the metal while the elastic one was done by attaching the walls to the metal with the help of sanitary silicone.Acoustic screens were made of OSB (Oriented Strand Board), a material available for use in both clamping modalities.The experiments were performed for two types of wall positioning, a variant with three walls and cover and a variant with five walls (cabin). The two variants were chosen because the number of walls was useful in identifying the differences between the values of the sound pressure level for both types of experiments.The results obtained at the end of the experiments showed better values for the rigid clamping of walls, with a reduction in the sound pressure level of up to 3 dB.The differences between the values of sound pressure level for the two types of clamping were quite small, sometimes minor. Key words: industrial noise, acoustic screen, rigid clamping, elastic clamping. 64
<strong>First</strong> <strong>International</strong> <strong>Conference</strong> on MOLDAVIAN RISKS - FROM GLOBAL TO LOCAL SCALE 16-19 May 2012, Bacau, Romania COMPARATIVE STUDY VIEWING THE EFFICIENCY OF THE GRANULAR FILTERS DEPENDING ON THE TYPE OF THE FILTER MATERIAL Oana (Irimia) Tirtoaca, Valentin Nedeff, Mirela Panainte “Vasile Alecsandri” University of Bacau, Department of Environmental Engineering and Mechanical Engineering Corresponding author: Tirtoaca (Irimia) Oana, oana.tartoaca@ub.ro Abstract: Water’s quality can be defined through a series of properties that limit the water’s exploitation. In order to accomplish the accordance with quality standards required for a specific demand (potable water, industrial water of different categories, ultrapure water), the continental surface water is treated through a sequence of operations and unit processes. The technological installation of treatment accomplishes, partially or totally, the disposal of the pollutants, every treatment proceeding being used for improving one or more qualitative parameter. The chosen treatment proceeding is specific to the type of the alimentation source and to the followed purpose (the production of the potable water, of industrial water for different categories). One of the basic proceedings for treating water is represented by the mechanical filtration of the water. The operation of filtering is influenced by a series of parameters, from which, the ones characteristic to the filter layer have a very special importance: nature, surface, thickness, pores dimension, the shape of the granular particles, hydrodynamic resistance, chemical resistance, mechanical resistance. The present paper aims to identify the type of granular filtering material that has the highest degree of retention concerning the storage of the solid particles. For discharging the solid suspensions that are found in water in concentrations between 5 – 50 mg/L, granular filtering materials are the most used (quartz sand, anthracite, perlite, barite, granate). In order to accomplish the experiments (the separation of the liquid – solid mixture) were carried out studies for three types of filtering materials with granular shape particles, respectively: quartz sand, perlite and anthracite. Using this types of materials were constituted granular filters with different thicknesses and the water passed through these filters with different intake flows in order to be filtrated. From the experiments accomplished for the three types of filtering materials it was identified the type of granular filtering material with the highest degree of retention in water’s mechanical filtering process. Key words: potable water, water’s mechanical treatment, filtration, filter materials. 65
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