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Kurt Fehling - One of the best experts on this subject based on the ideXlab platform.

  • Chrysotile asbestos exposure associated with removal of automobile Exhaust Systems (ca. 1945–1975) by mechanics: Results of a simulation study
    Journal of Exposure Science & Environmental Epidemiology, 2006
    Co-Authors: Dennis J Paustenbach, Amy K Madl, Ellen Donovan, Katherine Clark, Kurt Fehling
    Abstract:

    For decades, asbestos-containing gaskets were used in virtually every system that involved the transport of fluids or gases. Prior to the mid-1970s, some automobile Exhaust Systems contained asbestos gaskets either at flanges along the Exhaust pipes or at the Exhaust manifolds of the engine. A limited number of automobile mufflers were lined with asbestos paper. This paper describes a simulation study that characterized personal and bystander exposures to asbestos during the removal of automobile Exhaust Systems (ca. 1945–1975) containing asbestos gaskets. A total of 16 pre-1974 vehicles with old or original Exhaust Systems were studied. Of the 16 vehicles, 12 contained asbestos gaskets in the Exhaust system and two vehicles had asbestos lining inside the muffler. A total of 82 samples (23 personal, 38 bystander, and 21 indoor background) were analyzed by Phase Contrast Microscopy (PCM) and 88 samples (25 personal, 41 bystander, and 22 indoor background) by Transmission Electron Microscopy (TEM). Only seven of 25 worker samples analyzed by TEM detected asbestos fibers and 18 were below the analytical sensitivity limit (mean 0.013 f/cc, range 0.001–0.074 f/cc). Applying the ratio of asbestos fibers:total fibers (including non-asbestos) as determined by TEM to the PCM results showed an average (1 h) adjusted PCM worker exposure of 0.018 f/cc (0.002–0.04 f/cc). The average (1 h) adjusted PCM airborne concentration for bystanders was 0.008 f/cc (range 0.0008–0.015 f/cc). Assuming a mechanic can replace four automobile single Exhaust Systems in 1 workday, the estimated 8-h time-weighted average (TWA) for a mechanic performing this work was 0.01 f/cc. Under a scenario where a mechanic might repeatedly conduct Exhaust work, these results suggest that exposures to asbestos from work with automobile Exhaust Systems during the 1950s through the 1970s containing asbestos gaskets were substantially below 0.1 f/cc, the current PEL for chrysotile asbestos, and quite often were not detectable.

  • chrysotile asbestos exposure associated with removal of automobile Exhaust Systems ca 1945 1975 by mechanics results of a simulation study
    Journal of Exposure Science and Environmental Epidemiology, 2006
    Co-Authors: Dennis J Paustenbach, Amy K Madl, Katherine Clark, Kurt Fehling, Ellen P Donovan, Terry C Lee
    Abstract:

    For decades, asbestos-containing gaskets were used in virtually every system that involved the transport of fluids or gases. Prior to the mid-1970s, some automobile Exhaust Systems contained asbestos gaskets either at flanges along the Exhaust pipes or at the Exhaust manifolds of the engine. A limited number of automobile mufflers were lined with asbestos paper. This paper describes a simulation study that characterized personal and bystander exposures to asbestos during the removal of automobile Exhaust Systems (ca. 1945–1975) containing asbestos gaskets. A total of 16 pre-1974 vehicles with old or original Exhaust Systems were studied. Of the 16 vehicles, 12 contained asbestos gaskets in the Exhaust system and two vehicles had asbestos lining inside the muffler. A total of 82 samples (23 personal, 38 bystander, and 21 indoor background) were analyzed by Phase Contrast Microscopy (PCM) and 88 samples (25 personal, 41 bystander, and 22 indoor background) by Transmission Electron Microscopy (TEM). Only seven of 25 worker samples analyzed by TEM detected asbestos fibers and 18 were below the analytical sensitivity limit (mean 0.013 f/cc, range 0.001–0.074 f/cc). Applying the ratio of asbestos fibers:total fibers (including non-asbestos) as determined by TEM to the PCM results showed an average (1 h) adjusted PCM worker exposure of 0.018 f/cc (0.002–0.04 f/cc). The average (1 h) adjusted PCM airborne concentration for bystanders was 0.008 f/cc (range 0.0008–0.015 f/cc). Assuming a mechanic can replace four automobile single Exhaust Systems in 1 workday, the estimated 8-h time-weighted average (TWA) for a mechanic performing this work was 0.01 f/cc. Under a scenario where a mechanic might repeatedly conduct Exhaust work, these results suggest that exposures to asbestos from work with automobile Exhaust Systems during the 1950s through the 1970s containing asbestos gaskets were substantially below 0.1 f/cc, the current PEL for chrysotile asbestos, and quite often were not detectable.

Dennis J Paustenbach - One of the best experts on this subject based on the ideXlab platform.

  • Chrysotile asbestos exposure associated with removal of automobile Exhaust Systems (ca. 1945–1975) by mechanics: Results of a simulation study
    Journal of Exposure Science & Environmental Epidemiology, 2006
    Co-Authors: Dennis J Paustenbach, Amy K Madl, Ellen Donovan, Katherine Clark, Kurt Fehling
    Abstract:

    For decades, asbestos-containing gaskets were used in virtually every system that involved the transport of fluids or gases. Prior to the mid-1970s, some automobile Exhaust Systems contained asbestos gaskets either at flanges along the Exhaust pipes or at the Exhaust manifolds of the engine. A limited number of automobile mufflers were lined with asbestos paper. This paper describes a simulation study that characterized personal and bystander exposures to asbestos during the removal of automobile Exhaust Systems (ca. 1945–1975) containing asbestos gaskets. A total of 16 pre-1974 vehicles with old or original Exhaust Systems were studied. Of the 16 vehicles, 12 contained asbestos gaskets in the Exhaust system and two vehicles had asbestos lining inside the muffler. A total of 82 samples (23 personal, 38 bystander, and 21 indoor background) were analyzed by Phase Contrast Microscopy (PCM) and 88 samples (25 personal, 41 bystander, and 22 indoor background) by Transmission Electron Microscopy (TEM). Only seven of 25 worker samples analyzed by TEM detected asbestos fibers and 18 were below the analytical sensitivity limit (mean 0.013 f/cc, range 0.001–0.074 f/cc). Applying the ratio of asbestos fibers:total fibers (including non-asbestos) as determined by TEM to the PCM results showed an average (1 h) adjusted PCM worker exposure of 0.018 f/cc (0.002–0.04 f/cc). The average (1 h) adjusted PCM airborne concentration for bystanders was 0.008 f/cc (range 0.0008–0.015 f/cc). Assuming a mechanic can replace four automobile single Exhaust Systems in 1 workday, the estimated 8-h time-weighted average (TWA) for a mechanic performing this work was 0.01 f/cc. Under a scenario where a mechanic might repeatedly conduct Exhaust work, these results suggest that exposures to asbestos from work with automobile Exhaust Systems during the 1950s through the 1970s containing asbestos gaskets were substantially below 0.1 f/cc, the current PEL for chrysotile asbestos, and quite often were not detectable.

  • chrysotile asbestos exposure associated with removal of automobile Exhaust Systems ca 1945 1975 by mechanics results of a simulation study
    Journal of Exposure Science and Environmental Epidemiology, 2006
    Co-Authors: Dennis J Paustenbach, Amy K Madl, Katherine Clark, Kurt Fehling, Ellen P Donovan, Terry C Lee
    Abstract:

    For decades, asbestos-containing gaskets were used in virtually every system that involved the transport of fluids or gases. Prior to the mid-1970s, some automobile Exhaust Systems contained asbestos gaskets either at flanges along the Exhaust pipes or at the Exhaust manifolds of the engine. A limited number of automobile mufflers were lined with asbestos paper. This paper describes a simulation study that characterized personal and bystander exposures to asbestos during the removal of automobile Exhaust Systems (ca. 1945–1975) containing asbestos gaskets. A total of 16 pre-1974 vehicles with old or original Exhaust Systems were studied. Of the 16 vehicles, 12 contained asbestos gaskets in the Exhaust system and two vehicles had asbestos lining inside the muffler. A total of 82 samples (23 personal, 38 bystander, and 21 indoor background) were analyzed by Phase Contrast Microscopy (PCM) and 88 samples (25 personal, 41 bystander, and 22 indoor background) by Transmission Electron Microscopy (TEM). Only seven of 25 worker samples analyzed by TEM detected asbestos fibers and 18 were below the analytical sensitivity limit (mean 0.013 f/cc, range 0.001–0.074 f/cc). Applying the ratio of asbestos fibers:total fibers (including non-asbestos) as determined by TEM to the PCM results showed an average (1 h) adjusted PCM worker exposure of 0.018 f/cc (0.002–0.04 f/cc). The average (1 h) adjusted PCM airborne concentration for bystanders was 0.008 f/cc (range 0.0008–0.015 f/cc). Assuming a mechanic can replace four automobile single Exhaust Systems in 1 workday, the estimated 8-h time-weighted average (TWA) for a mechanic performing this work was 0.01 f/cc. Under a scenario where a mechanic might repeatedly conduct Exhaust work, these results suggest that exposures to asbestos from work with automobile Exhaust Systems during the 1950s through the 1970s containing asbestos gaskets were substantially below 0.1 f/cc, the current PEL for chrysotile asbestos, and quite often were not detectable.

M Cross - One of the best experts on this subject based on the ideXlab platform.

  • the recovery mechanism of platinum group metals from catalytic converters in spent automotive Exhaust Systems
    Resources Conservation and Recycling, 2000
    Co-Authors: M. Benson, J. E. Harry, C R Bennett, M. K. Patel, M Cross
    Abstract:

    The recovery of platinum group metals (PGMs) from catalytic converters of spent Exhaust Systems is considered in this paper. To be cost-effective, recovery processes must be well over 90% efficient and so the optimisation of their operation is vital. Effective optimisation requires a sound understanding of the operation and the underlying process mechanisms. This paper focuses on pyrometallurgical recovery operations used and typified by the Johnson–Matthey process. Analysis of this process reveals that it cannot be simply explained by the gravity model that is normally assumed. The analysis reveals that the affinity of PGM particles for the melted collector metal is a key factor in the behaviour of the process. A rational explanation of the key issues that govern the process behaviour is proposed and shown to be consistent with available operational data. The results generated would be applicable to other similar processes.

  • the recovery mechanism of platinum group metals from catalytic converters in spent automotive Exhaust Systems
    Resources Conservation and Recycling, 2000
    Co-Authors: M. Benson, J. E. Harry, C R Bennett, M. K. Patel, M Cross
    Abstract:

    The recovery of platinum group metals (PGMs) from catalytic converters of spent Exhaust Systems is considered in this paper. To be cost-effective, recovery processes must be well over 90% efficient and so the optimisation of their operation is vital. Effective optimisation requires a sound understanding of the operation and the underlying process mechanisms. This paper focuses on pyrometallurgical recovery operations used and typified by the Johnson–Matthey process. Analysis of this process reveals that it cannot be simply explained by the gravity model that is normally assumed. The analysis reveals that the affinity of PGM particles for the melted collector metal is a key factor in the behaviour of the process. A rational explanation of the key issues that govern the process behaviour is proposed and shown to be consistent with available operational data. The results generated would be applicable to other similar processes.

Victor Daniel Jimenez - One of the best experts on this subject based on the ideXlab platform.

  • heat transfer modeling in Exhaust Systems of high performance two stroke engines
    Applied Thermal Engineering, 2014
    Co-Authors: J M Lujan, H Climent, Pablo Olmeda, Victor Daniel Jimenez
    Abstract:

    Abstract Heat transfer from the hot gases to the wall in Exhaust Systems of high-performance two-stroke engines is underestimated using steady state with fully developed flow empirical correlations. This fact is detected when comparing measured and modeled pressure pulses in different positions in the Exhaust system. This can be explained taking into account that classical expressions have been validated for fully developed flows, a situation that is far from the flow behavior in reciprocating internal combustion engines. Several researches have solved this phenomenon in four-stroke engines, suggesting that the unsteady flow is strongly linked to the heat transfer. This research evaluates the correlations proposed by other authors in four stroke engines and introduces a new heat transfer model for Exhaust Systems in two-stroke, high performance, gasoline engines. The model, which accounts for both the entrance length effect and flow velocity fluctuations, is validated against experimental measurements. Comparisons of the proposed model with other models are performed, showing not negligible differences in the scavenge process related parameters.

Terry C Lee - One of the best experts on this subject based on the ideXlab platform.

  • chrysotile asbestos exposure associated with removal of automobile Exhaust Systems ca 1945 1975 by mechanics results of a simulation study
    Journal of Exposure Science and Environmental Epidemiology, 2006
    Co-Authors: Dennis J Paustenbach, Amy K Madl, Katherine Clark, Kurt Fehling, Ellen P Donovan, Terry C Lee
    Abstract:

    For decades, asbestos-containing gaskets were used in virtually every system that involved the transport of fluids or gases. Prior to the mid-1970s, some automobile Exhaust Systems contained asbestos gaskets either at flanges along the Exhaust pipes or at the Exhaust manifolds of the engine. A limited number of automobile mufflers were lined with asbestos paper. This paper describes a simulation study that characterized personal and bystander exposures to asbestos during the removal of automobile Exhaust Systems (ca. 1945–1975) containing asbestos gaskets. A total of 16 pre-1974 vehicles with old or original Exhaust Systems were studied. Of the 16 vehicles, 12 contained asbestos gaskets in the Exhaust system and two vehicles had asbestos lining inside the muffler. A total of 82 samples (23 personal, 38 bystander, and 21 indoor background) were analyzed by Phase Contrast Microscopy (PCM) and 88 samples (25 personal, 41 bystander, and 22 indoor background) by Transmission Electron Microscopy (TEM). Only seven of 25 worker samples analyzed by TEM detected asbestos fibers and 18 were below the analytical sensitivity limit (mean 0.013 f/cc, range 0.001–0.074 f/cc). Applying the ratio of asbestos fibers:total fibers (including non-asbestos) as determined by TEM to the PCM results showed an average (1 h) adjusted PCM worker exposure of 0.018 f/cc (0.002–0.04 f/cc). The average (1 h) adjusted PCM airborne concentration for bystanders was 0.008 f/cc (range 0.0008–0.015 f/cc). Assuming a mechanic can replace four automobile single Exhaust Systems in 1 workday, the estimated 8-h time-weighted average (TWA) for a mechanic performing this work was 0.01 f/cc. Under a scenario where a mechanic might repeatedly conduct Exhaust work, these results suggest that exposures to asbestos from work with automobile Exhaust Systems during the 1950s through the 1970s containing asbestos gaskets were substantially below 0.1 f/cc, the current PEL for chrysotile asbestos, and quite often were not detectable.