Effects of heating, breathing, hair style, posture, and air velocity on breathing zone concentrations for an anthropometrically-correct manikin in a wind tunnel

El-Nahas, W.

doi:10.33915/etd.4146

Cited by 2 publications

(6 citation statements)

References 22 publications

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“…Since C nose and C mouth were correlated each other, the effects of V face on average C nose ( Figure 5.8) were very similar to the effects of V face on average C mouth ( Figure 5.9). For the range of V face = 100 to 220 fpm, C nose and C mouth dropped consistently as V face increased, which is in general agreement with previous studies (Li et al, 2007;Elnahas, 2005;Guffey and Barnea, 1994;He, 2010). This agreement suggests that V face is an important factor affecting levels of airborne contaminants in the breathing zone for the simple manikin.…”

Section: Effect Of V Face On C Nose and C Mouthsupporting

confidence: 91%

“…The breathing zone is supposed to be a volume throughout which concentrations are all equal to the inhaled concentrations. Different concentrations at different points in what would be considered in the "breathing zone" were reported by Elnahas (2005). The tested sample locations were the right collar, left collar, right lapel, left lapel, mouth, nose, forehead, center chest, and neck.…”

Section: Manikin In Free-stream Studiesmentioning

confidence: 99%

“…On the other hand, the Occupational Safety and Health Administration (OSHA) defined this breathing zone to be a hemisphere of roughly 6-9 inches around the head. As a result, to represent worker exposure, sampling was carried 20 out at different locations in the breathing zone (Martinelli et al, 1983;Cohen et al, 1984;Van Del Wal and Moerkerken, 1984;Elnahas, 2005). Martinelli et al (1983) monitored and recorded the aerosol concentrations at the forehead, nose, and lapel during the process of melting and casting in a beryllium refinery.…”

Section: Human Subject Studiesmentioning

confidence: 99%

“…El-Sotouhy (2008) compared human subjects' experimental results with Elnahas's (2005) anthropometrically-correct manikin results under free-stream conditions. In both studies the subjects hold the source in their hands.…”

Section: Human Subject Studiesmentioning

confidence: 99%

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Tracer Gas Exposure of Human Subjects Doing Simulated Work at a Benchtop Enclosing Hood in a Wind Tunnel

Carreno-Chavez¹

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Local exhaust ventilation devices (LEV) are critical in protecting workers from harmful airborne contaminants. The aim of this study is to investigate the factors that affect the performance of a benchtop enclosing hood. A Freon 134ahelium mixture was released from a 9" diameter pie-pan placed on the floor of a 30" high by 36" wide hood at 2" from the hood face. Freon 134a was measured close to the nose and mouth for a simple manikin (unheated and not breathing), a complex manikin (heated and breathing), and ten human subjects at different times while they stood at the face of the hood in a wind tunnel. Air was drawn from probe openings at the manikin and human subjects' faces at 0.20 lpm into 5 liter sampling bags for 20 minutes each. In a factorial study design, the manikins and the human subjects were tested at hood face velocity (V face) levels from 100 to 220 fpm and wind tunnel cross-draft velocity (V cross) levels from 14 to 63 fpm. The temperature difference (∆T) between the subject's body and the environment was also recorded. The results show that V face plays an important role on subjects' exposure. In general, the exposures decreased as V face increased. A statistically significant effect (p < 0.001) of V face on log-transformed exposure at the nose and mouth (log C nose and log C mouth) was found for both the simple manikin and the human subjects; in contrast, this effect was only found on log C mouth for the complex manikin. Crossv ACKNOWLEDGMENTS This dissertation was made possible by the love and constant support of all my family members. I feel so lucky to have them in my life. I would like to thank my parents Tomás and Doris, my brothers Wilmer and Edgardo, my sister Yliana, and my nieces Yanira and Issely for their unconditional love, support, and continuous encouragement during my studies at West Virginia University. I would like to give my sincere gratitude to my research advisor and committee chair Dr. Steven Guffey for his encouragement, support, and invaluable guidance through the different stages of this project. I learned many things from his expertise in the area during many hours of conversation. I would also like to thank my research co-advisor, Dr. Ismail Celik, for his initial support for the project and his insights and encouragement in this study.

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Section: Effect Of V Face On C Nose and C Mouthsupporting

confidence: 91%

Section: Manikin In Free-stream Studiesmentioning

confidence: 99%

Section: Human Subject Studiesmentioning

confidence: 99%

Section: Human Subject Studiesmentioning

confidence: 99%

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Tracer Gas Exposure of Human Subjects Doing Simulated Work at a Benchtop Enclosing Hood in a Wind Tunnel

Carreno-Chavez¹

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“…The dependent variables include the concentrations of the contaminant within the breathing zone (CBZ) of the operator and the concentrations of the contaminant located far downstream within the duct (Cduct). Since previous studies (Elnahass, 2005;Kasberger, 2012) found sampling at the mouth and nose to be redundant, the breathing zone samples were collected at a single point between the mouth and nose.…”

Section: Methodsmentioning

confidence: 99%

Effects of a Manikin on the Capture Efficiency and Protection Efficiency of a Small Rectangular Hood

Geissler¹

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The primary indicator of capturing hood effectiveness is widely assumed to be the "capture velocity" measured normal to the center of the hood face, at the furthest location of the contaminant source. The velocity required at this distance (Vx) is thought to correspond to the appropriate flow (Q) required to capture the contaminant. The adequacy of Vx as a surrogate for hood effectiveness has long been poorly understood and has been little studied. Few considerations of potentially disruptive parameters, such as draft velocity, hood orientation, and operator presence are made during the design phase. In this study, an anatomically correct heated, breathing, and moving manikin was used as a surrogate for a human hood operator. Velocity profiles of the capture envelope were obtained by particle image velocimetry (PIV) at three orientations (0˚, 90˚, 180˚), with respect to the cross drafts (30, 60, and 120 fpm) generated inside a large wind tunnel. The capturing hood fan speed was set to maintain the Q of nominal Vx values of 50, 100, and 200 fpm, as measured 11 inches away from the hood face, in a controlled environment. A condensation particle counter (CPC) was used to compare the capture efficiency and protection efficiency of the rectangular hood with the traditional, expensive, and time-consuming tracer gas method. Salt aerosols and Freon 134-A were released, at separate occasions, 11 inches away from the hood face. Measurements were taken within the duct (Cduct) and between the mouth and nose (CBreathingZone) of the manikin. Duct measurements (Cduct100) were also collected when the contaminant was directly fed into the duct, and breathing zone measurements were also conducted with the hood turned off (CBreathingZone100). The capture efficiency results of each method were compared, and no significant difference between the methods was found. With the CPC method established as a viable method, studies were conducted to test the effects of operator presence, movement, hood orientation, and cross drafts under the same conditions as the PIV study. All effects, except for manikin movement, were found to have a significant effect on hood performance. Manikin movement did, however, have a significant effect on contaminant concentrations within the breathing zone of the operator.

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Effects of heating, breathing, hair style, posture, and air velocity on breathing zone concentrations for an anthropometrically-correct manikin in a wind tunnel

Abstract: In partial fulfillment of the requirements for the degree of

Cited by 2 publications

References 22 publications

Tracer Gas Exposure of Human Subjects Doing Simulated Work at a Benchtop Enclosing Hood in a Wind Tunnel

Tracer Gas Exposure of Human Subjects Doing Simulated Work at a Benchtop Enclosing Hood in a Wind Tunnel

Effects of a Manikin on the Capture Efficiency and Protection Efficiency of a Small Rectangular Hood

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