The Experts below are selected from a list of 2433 Experts worldwide ranked by ideXlab platform
Pam Susi - One of the best experts on this subject based on the ideXlab platform.
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local exhaust ventilation for the Control of welding Fumes in the construction industry a literature review
Annals of Occupational Hygiene, 2012Co-Authors: Michael R. Flynn, Pam SusiAbstract:Arc welding is a common unit operation in the construction industry, where frequent changes in location and welding position make it more difficult to Control Fume exposures than in industries where fixed locations are the norm. Welders may be exposed to a variety of toxic airborne contaminants including manganese (Mn) and hexavalent chromium (CrVI). Local exhaust ventilation (LEV) is a well-known engineering Control for welding Fumes but has not been adopted widely in the construction industry. This literature review presents data on the performance of a variety of LEV systems for welding Fume Control from the construction (five references), shipyard (five references), and other industries. The studies indicate that LEV can reduce Fume exposures to total particulate, Mn, and CrVI to levels below currently relevant standards. Field studies suggest that 40-50% or more reduction in exposure is possible with portable or fixed LEV systems relative to natural ventilation but that correct positioning of the hood and adequate exhaust flow rates are essential. Successful implementation of extraction guns for gas metal arc welding (GMAW) and flux core arc welding has been demonstrated, indicating that a successful balance between extraction airflow and shielding gas requirements is possible. Work practices are an important part of achieving successful Control of Fume exposures; in particular, positioning the hood close to the arc, checking exhaust flow rates, and avoiding the plume. Further research is needed on hood size effects for Controlling welding Fume with portable LEV systems and identifying and overcoming barriers to LEV use in construction.
Michael R. Flynn - One of the best experts on this subject based on the ideXlab platform.
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local exhaust ventilation for the Control of welding Fumes in the construction industry a literature review
Annals of Occupational Hygiene, 2012Co-Authors: Michael R. Flynn, Pam SusiAbstract:Arc welding is a common unit operation in the construction industry, where frequent changes in location and welding position make it more difficult to Control Fume exposures than in industries where fixed locations are the norm. Welders may be exposed to a variety of toxic airborne contaminants including manganese (Mn) and hexavalent chromium (CrVI). Local exhaust ventilation (LEV) is a well-known engineering Control for welding Fumes but has not been adopted widely in the construction industry. This literature review presents data on the performance of a variety of LEV systems for welding Fume Control from the construction (five references), shipyard (five references), and other industries. The studies indicate that LEV can reduce Fume exposures to total particulate, Mn, and CrVI to levels below currently relevant standards. Field studies suggest that 40-50% or more reduction in exposure is possible with portable or fixed LEV systems relative to natural ventilation but that correct positioning of the hood and adequate exhaust flow rates are essential. Successful implementation of extraction guns for gas metal arc welding (GMAW) and flux core arc welding has been demonstrated, indicating that a successful balance between extraction airflow and shielding gas requirements is possible. Work practices are an important part of achieving successful Control of Fume exposures; in particular, positioning the hood close to the arc, checking exhaust flow rates, and avoiding the plume. Further research is needed on hood size effects for Controlling welding Fume with portable LEV systems and identifying and overcoming barriers to LEV use in construction.
Hamidou Diawara - One of the best experts on this subject based on the ideXlab platform.
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abrasion resistance of fine aggregate replaced silica Fume concrete
Materials, 1999Co-Authors: Nader Ghafoori, Hamidou DiawaraAbstract:This investigation evaluated the resistance to abrasion of concrete proportioned to have four levels of fine aggregate replacement (5%, 10%, 15%, and 20%) with silica Fume. Control mixtures containing no silica Fume were also used for comparison purposes. Three cement factors, namely, 500 lb/cu yd (900 kg/cu m), 650 lb/cu yd (1,157 kg/cu m), and 800 lb/cu yd (1,424 kg/cu m), and two water-to-cementitious materials ratios (w/cm)--0.325 and 0.40)--were employed. The fresh and bulk characteristics, such as slump, air content, time of setting, bleeding, unit weight, and compressive strength, were examined to characterize the selected matrixes. The standard testing method--American Society for Testing and Materials (ASTM) C 779, Procedure C, Ball Bearing--was used to ascertain the resistance to wear. The influence of silica Fume addition, cement factor, w/cm, and curing were studied. The relationship between depth of wear and compressive strength was also presented. Finally, the fresh properties, compressive strength (and strength development), and abrasion resistance of the fine aggregate-replaced silica Fume concretes were compared with those of the reference mixtures. Laboratory test results concluded that the resistance to wear of concrete containing silica Fume as a fine aggregate replacement was consistently better with increasing amounts of silica Fume up to 10%. The abrasion resistance and compressive strength decreased with increases in w/cm and improved with increases in cement factor and curing age. Both compressive strength and resistance to wear of fine aggregate-replaced silica Fume concretes were better than those exhibited by the equivalent Control matrixes. A significant correlation was found between the depth of wear and compressive strength.
Nader Ghafoori - One of the best experts on this subject based on the ideXlab platform.
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abrasion resistance of fine aggregate replaced silica Fume concrete
Materials, 1999Co-Authors: Nader Ghafoori, Hamidou DiawaraAbstract:This investigation evaluated the resistance to abrasion of concrete proportioned to have four levels of fine aggregate replacement (5%, 10%, 15%, and 20%) with silica Fume. Control mixtures containing no silica Fume were also used for comparison purposes. Three cement factors, namely, 500 lb/cu yd (900 kg/cu m), 650 lb/cu yd (1,157 kg/cu m), and 800 lb/cu yd (1,424 kg/cu m), and two water-to-cementitious materials ratios (w/cm)--0.325 and 0.40)--were employed. The fresh and bulk characteristics, such as slump, air content, time of setting, bleeding, unit weight, and compressive strength, were examined to characterize the selected matrixes. The standard testing method--American Society for Testing and Materials (ASTM) C 779, Procedure C, Ball Bearing--was used to ascertain the resistance to wear. The influence of silica Fume addition, cement factor, w/cm, and curing were studied. The relationship between depth of wear and compressive strength was also presented. Finally, the fresh properties, compressive strength (and strength development), and abrasion resistance of the fine aggregate-replaced silica Fume concretes were compared with those of the reference mixtures. Laboratory test results concluded that the resistance to wear of concrete containing silica Fume as a fine aggregate replacement was consistently better with increasing amounts of silica Fume up to 10%. The abrasion resistance and compressive strength decreased with increases in w/cm and improved with increases in cement factor and curing age. Both compressive strength and resistance to wear of fine aggregate-replaced silica Fume concretes were better than those exhibited by the equivalent Control matrixes. A significant correlation was found between the depth of wear and compressive strength.
Sargetis Jeshua - One of the best experts on this subject based on the ideXlab platform.
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EVALUATION OF PARTICULATE METAL AND NOISE EXPOSURES AT A FOUNDRY AND RECOMMENDED Control STRATEGIES
Digital Commons @ Montana Tech, 2016Co-Authors: Sargetis JeshuaAbstract:An evaluation of current industrial hygiene practices were performed at a foundry located in the Northwestern United States. The foundry was evaluated for respirable and inhalable manganese, respirable crystalline silica and noise exposure. Personal breathing zone sampling was performed using proper safety and health practices on workers in the foundry and around the entire facility. Results showed that workers were being exposed to respirable manganese but not inhalable manganese. Bulk crystalline silica sampling was performed and personal breathing zone sampling was performed as a follow up to certain Control measures which showed low concentrations. Area noise sampling was conducted in various parts of the facility and personal noise dosimetry was performed on workers in all areas of the facility. Noise exposure above the OSHA PEL was found in a few sites but most of the limits were above the OSHA Hearing Conservation criterion. Few locations were over the NIOSH and ACGIH criterions. Engineering Control measures included a ventilation system being installed above the furnaces, for metal Fume Control, the paving of a back lot to reduce exogenous crystalline silica from the foundry. Hearing protection, along with the inclusion of a revised hearing conservation program, was also implemented for reduced worker exposure
