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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 STUDY UPON THE ADVANTAGES OF PREDICTIVE MAINTENANCE IN MONITORING OF ROLLING BEARINGS Dumitru-Cristinel Nadabaica, Valentin Nedeff, Luminita Bibire, Gabriela Andrioai “Vasile Alecsandri” University of Bacau, Department of Environmental Engineering and Mechanical Engineering Corresponding author: Dumitru-Cristinel Nadabaica, nadabaica.dumitru@ub.ro Abstract: This paper presents a theoretical study of the application of vibration envelope technique in the diagnosis of rolling bearings with the purpose of estimating their remaining lifetime and of determining the most advantageous time to perform the replacement of rolling bearings in the maintenance activity. Rolling bearings are the most common components of dynamic equipments and they are also the most sensitive to stresses during operation. The increasing of level vibration contributes to the reduction of the rolling bearings lifetime. The envelope is a technique of vibration signal processing which is required for the extraction of the defect characteristic frequency from the frequency spectrums. By using the envelope technique the premature wear of rolling bearings can be monitored. Rolling bearings are predisposed to a premature wear due to the execution and mounting quality, to the loading conditions during operation, to the very numerous cycles of operation etc. The premature wear is manifested by: 1. the generation of noise (noise pollution); 2. the loss of lubricant (high consumption of raw materials, environmental pollution); 3. the failure of other components (leading to the out of use of the rolling bearing, in a premature stage, which means both supplementary consumption of materials and energy for producing new components, and indirectly for increasing the amount of waste); 4. extra energy consumption (one third of all energy is consumed to defeating of unwanted friction). This study also presents the benefits of the predictive maintenance application in direct connection to the minimization of waste quantities and to the environmental pollution. In the same time, by condition monitoring and diagnostic of process equipment, the predictive maintenance has an important role about costs of maintenance activity because one third of these costs are lost because the application of improper or unnecessary maintenance. Damages made by an improper maintenance can cause disasters at a large scale, having negative consequences for people and for the environment. Keywords: predictive maintenance, enveloping technique of vibration, noise pollution, minimization of waste quantities, consumption of materials and energy. 66
<strong>First</strong> <strong>International</strong> <strong>Conference</strong> on MOLDAVIAN RISKS - FROM GLOBAL TO LOCAL SCALE 16-19 May 2012, Bacau, Romania STUDIES AND RESEARCH ON THE INFLUENCE OF THE CLIMATIC FACTORS ON AMMONIA POLLUTION IN BACAU Doina Capsa 1 , Valentin Nedeff 2 , Mirela Panainte 2 , Narcis Barsan 2 1 Regional weather forecasting service Bacau 2 “Vasile Alecsandri" University of Bacau, Department of Environmental Engineering and Mechanical Engineering Corresponding author: Capsa Doina, doina_capsa@yahoo.com Abstract: Air pollution occurs after elimination in the air, especially over large urban areas, of three categories of substances: gas (carbon dioxide, carbon monoxide, unburned hydrocarbons, hydrogen sulphide, sulfur dioxide, ammonia, fluorine, and chlorine), particulate matter and oxides metals (Pb, Hg and others). The quality of the air in the urban areas it depends especially on the type and the size of the industrial activities, the intensity of the traffic, and the quality of waste management both domestic and industrial. Besides these factors we could add the population density, the size and the quality of the open spaces, the geographical and climatologically conditions. In Bacau County the air quality is continuous monitored by measurements of three automatic stations located in areas representative of the types of existing stations. This monitoring system was implemented by Romanian National Agency for Environmental Protection to measure the variable values of the principal pollutants from air. These types of systems are in concordance with national legislation on protection of the atmosphere and comply with the requirements of European regulations. Using the data from the meteorological station in Bacau and the reports of the Regional Agency for Environmental Protection Bacau, the influence of the climatic factors is analyzed under the maximum allowable limits that are exceeded for ammonia. The main source of the ammonia air pollution in the city of Bacau is the industry but we also have the intensive animal breeding. The scope of the pollution accidents is given by the variation in time of the climatic factors, that can promote rapid dispersion of the pollutant, and thus reducing the negative effects but they can adversely affect air quality. Excesses of the limit value of 0,3 mg\m 3 NH3 with values of 10 - 100 % they are persisted in air in different life times according to the different meteorological conditions. The mesoscale analysis of the climatic factors in terms of an excess of 10 till 100 the maximum permissible value of the pollutant lead to the conclusion that the intensity and the wind direction, the air temperature, the gradient barre and the weather, the fog and the precipitations are factors that determine the variation amount pollutant in time. Key words: air pollution, monitoring system, ammonia air pollution, climatic factors. 67
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