The influence of orifice height on flow rate of powder excipients.
The influence of the orifice height of a cylindrical, flat-bottomed hopper on the mass flow rate of the free-flowable size fractions of sodium chloride and boric acid was investigated. It was observed that a zone of sudden acceleration of the mass flow under gravity occurred when a critical orifice height had been achieved. Based on the results, an orifice diameter equal to 12 mm with a height of between 8-16 mm is recommended for the faster flow of sodium chloride while an orifice diameter equal to 8 mm with a height of less than 8mm is appropriate for the slower flow of boric acid. In summary, the orifice height should be taken into consideration as an important parameter of a cylindrical test hopper in order to obtain a reproducible and comparable mass flow as the single-point characteristic of powder flowability.
Department of Pharmaceutical Technology, Charles University in Prague, Faculty of Pharmacy in Hradec Králové, Czech Republic.
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Zatloukal
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Sklubalová
D001888:Boric Acids; D005079:Excipients; D006813:Humidity; D010316:Particle Size; D011208:Powders; D015203:Reproducibility of Results; D012965:Sodium Chloride; D013678:Technology, Pharmaceutical / Q000592:standards*; D013696:Temperature; D014732:Vibration
D001888:Boric Acids; D005079:Excipients; D011208:Powders; D012965:Sodium Chloride; C032688:boric acid