Department of Pharmaceutical Technology, Charles University in Prague, Faculty of Pharmacy, Hradec Králové, Czech Republic.
Pharm Dev Technol. 2013 Feb;18(1):106-11. doi: 10.3109/10837450.2011.640686. Epub 2011 Dec 10.
Basic aspect of powder handling is powder flow which depends on mechanical properties of the solid material. This experimental work presents the results of flowability testing of the free-flowable particle size fraction of 0.0250-0.0315 cm of five powder excipients. The single-point determination of the mass flow rate from a cylindrical, flat-bottomed hopper was primarily influenced by the diameter of a circular orifice. The significant effect of the orifice height was also noted. Increasing the orifice height, the flow under gravity is directed resulting in the sudden acceleration of the flow rate. The critical zone relates to the orifice diameter. The multi-point determination of flowability employed the actual parameters of the flow equation which allows the prediction of the mass flow rate. The precision of the prediction was the basic criterion in optimization of the orifice geometry. Based on the results, the orifice height of 1.6 cm can be recommended for the correction of faster powder flow. For the slower powder flow, an orifice height of 0.2 cm can be used alternatively. In conclusion, the information about the orifice height used should be referred to whenever test the powder flowability and compare the results.
粉末处理的基本方面是粉末流动，这取决于固体材料的机械性能。这项实验工作展示了五种粉末辅料中 0.0250-0.0315cm 自由流动粒径部分的流动性测试结果。从圆柱形平底料斗中单点确定质量流速主要受圆形孔口直径的影响。还注意到孔口高度的显著影响。增加孔口高度，重力作用下的流动被引导，导致流速的突然加速。临界区域与孔口直径有关。使用流动方程的实际参数多点确定流动性，允许预测质量流速。预测的精度是优化孔几何形状的基本标准。基于结果，可以推荐使用 1.6cm 的孔口高度来校正更快的粉末流动。对于较慢的粉末流动，可以选择使用 0.2cm 的孔口高度。总之，在测试粉末流动性并比较结果时，应参考所用孔口高度的信息。
