Measuring Powder Flow Rate
Knowing the rate that powders flow is important for the success of pharmaceutical processes like capsule filling, tableting, blending and storage. "Flowbility" depends on the properties of the powder - particle size, shape, moisture content, etc - and the equipment used - hopper width, oriface diameter, etc. Researchers in Greece have been studying how the properties of powders affect their flowability.
The scientists monitor the mass flow rate of a powder by letting it flow through an orifice directly upon an A&D electronic balance. Using Windmill software, they continuously log readings from the balance, storing them alongside the time the readings were taken. The data is transferred to an Excel spreadsheet, and from the mass change per unit time they can calculate the flow rate in grams per second. The results of the study have now been published in the International Journal of Pharmaceutics, 250 (1), 13 - 23.
The balance is connected to a PC using an RS232 cable. The free Windmill 4.3 software includes a driver for laboratory instruments with RS232 ports. Called LabIML, this collects data from the A&D balance and passes it to other Windmill applications: Logger, Chart, DDE Panel, etc. To download your copy of the software, subscribe to the Monitor newsletter (ISSN 1472-0221). Alternatively, for the latest version of Windmill see the COMIML Serial Driver page in our on-line catalogue.
Kachrimanis K., Karamyan V., Malamataris S., 2003, Artificial neural networks (ANNs) and modeling of powder flow. International Journal of Pharmaceutics, 250 (1), 13 - 23.