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KMID : 0895420040140030243
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Journal of Korean Society of Occupational and Enviromental Hygiene
2004 Volume.14 No. 3 p.243 ~ p.250
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Measurements of Cross drafts Around Open Surface Tanks in Plating Shops
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Song Se-Wook
Kim Tae-Hyeung
Ha Hyun-Chul
Hong Jwa-Ryung
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Abstract
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Open surface tanks are used in a variety of industrial processes, such as picking and plating. Push-pull ventilation
system is often the best and most energy efficient way to remove any contaminant which evaporates from the open
surface tanks. Existing design guidelines are based on experimental and numerical works which is cannot easily be
extended to different operating conditions. Contaminant removal efficiency of push-pull ventilation could be affected
by various parameters, such as vessel shape, room location, cross draft, etc. Especially, the velocity of cross draft might
be one of influencing factors for the effective ventilation. To account for the effect of cross draft in case of over 0.4m/s, a flow adjustment of ±20% should be designed into the push and +20% into the pull flow system. For effective design and installation of push-pull system, we must be consider the magnitude of Cross draft velocity. However, the cross draft velocity of workplace installed push-pull ventilation system were not measured yet. In this paper, we measured the cross draft and door/window face velocities in 8 surface treatment shops in which the push-pull type open surface tanks are generally used. Two-directional hot-wire anemometer was used to measure the velocities after checking the main direction of flow by using smoke-tube. The experiments were performed in both winter and summer since the flow patterns and the velocities were thought to show the quite different seasonal variations. Mean cross draft velocities of winter and summer were measured as 0.60m/s and 0.62m/s, respectively, which is over the operating range, 0.4m/s. In addition, the face velocities through doors and windows were measured as 1.38m/s and 1.79m/s, respectively. The measured cross draft velocity is somewhat higher than 0.4m/s which is recommended for the push-pull hood by ACGIH design guideline. This high cross draft velocity could destroy the hood flow in the push-pull hood system. Thus, it is
imperative that the ACGIH design guide line should be modified in the near future.
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KEYWORD
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Push-pull hood, Cross draft, Open surface tank, picking and plating, Dual sensor hot wire anemometer
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