Heitbrink W A, Baron P A, Willeke K
U.S. Department of Health and Human Services, Centers for Disease Control, National Institute for Occupational Safety and Health, Cincinnati, OH 45226.
Am Ind Hyg Assoc J. 1992 Oct;53(10):617-24. doi: 10.1080/15298669291360256.
To identify the dust generation processes, aluminum oxide powder was dropped as a free falling slug in a test chamber. The effect of the slug's mass, diameter, and drop height upon the aerosol concentration and size distribution was measured with an aerodynamic particle sizer. To differentiate between aerosol generated during the free fall and at the end of the fall, the slug was dropped either onto a flat surface or into a container of water that suppressed dust generation associated with the impact at the end of the fall. Aerosol generation occurred during the slug's free fall as well as at the end of the fall. The falling solid induced an airflow that followed the falling solid to the end of the fall. This induced airflow contained the aerosol generated during the free fall. At the end of the free fall, the induced airflow, combined with air jets created on impact, dispersed the aerosol throughout the test chamber. Additional measurements were made by using "neutral buoyancy" helium-filled bubbles to visualize the airflow in the test chamber. The airflow and ensuing turbulence were sufficient to keep large, inspirable particles suspended throughout the test chamber for periods greater than 10 min. During experimental work, the effect of drop height, mass, and slug diameter upon aerosol generation by a single slug of powder was studied. The results indicated that the manner in which a powder is handled may be as important as material dustiness as measured by a dustiness tester. Aerosol generation can be reduced by minimizing the contact between the falling powder and the air.
为了确定粉尘产生过程，在试验箱中以自由落体块状形式投放氧化铝粉末。使用空气动力学粒度分析仪测量块状物的质量、直径和下落高度对气溶胶浓度和粒径分布的影响。为了区分自由落体过程中和落体结束时产生的气溶胶，将块状物要么投放到平面上，要么投放到抑制落体结束时撞击产生的粉尘的水中。在块状物自由落体过程中和落体结束时均会产生气溶胶。下落的固体引发了一股气流，该气流跟随下落的固体直至落体结束。这股引发的气流包含自由落体过程中产生的气溶胶。在自由落体结束时，引发的气流与撞击时产生的空气射流相结合，使气溶胶在整个试验箱中扩散。通过使用“中性浮力”充氦气泡来可视化试验箱中的气流，进行了额外的测量。气流和随之产生的湍流足以使大的可吸入颗粒在整个试验箱中悬浮超过10分钟。在实验工作中，研究了下落高度、质量和块状物直径对单块粉末产生气溶胶的影响。结果表明，粉末的处理方式可能与用粉尘测试仪测量的材料粉尘度同样重要。通过尽量减少下落粉末与空气之间的接触，可以减少气溶胶的产生。
