The local exhaust system is the preferred control method because it can remove contaminants by capturing them at or near the source. Exhaust ventilation is classified into two groups: the local exhaust system and the general exhaust system ( 1). To reduce worker exposure to hazards, exhaust ventilation systems are commonly used to remove the contaminants generated by the tasks or processes. Many processes in industry can expose workers to a wide variety of airborne particles. Statistical analysis shows that better control performance can be obtained with supply air velocity of 0.51 m/s (100 fpm) than with 0.41 m/s (80 fpm) and that use of curtains for downflow booths did not improve their control performance.Įxposure to airborne particles in the workplace can present a significant risk to worker health. Our study results show that only short-depth downflow booths failed to protect the worker performing powder transfer far from the booth exhausts. Statistical analysis compared particle reduction ratios obtained from various test conditions including booth size (short, regular, or extended), supply air velocity (0.41 and 0.51 m/s or 80 and 100 feet per minute, fpm), powder transfer location (near or far from the booth exhaust), and inclusion or exclusion of curtains at the booth entrance. An experimental study was conducted to thoroughly evaluate the control performance of downflow booths used for removing airborne particles generated by the transfer of powdered lactose between two containers. In this study, we designed and built a mobile downflow booth that is capable of quick assembly and easy size change to provide greater flexibility and particle control for various manufacturing processes or tasks.
The downflow booth provides unidirectional filtered airflow from the ceiling, entraining released particles away from the workers’ breathing zone, and delivers contained airflow to a lower level exhaust for removing particulates by filtering media. Compared to other common control measures, the downflow booth is a costly engineering control used to contain airborne dust or particles.
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