In powder technology it is often important directly measure real powder flow rate from a small amount of powder. For example, in pharmaceutical industry a frequent problem is to determine powder flow properties of new Active Pharmaceutical Ingredient (API) in an early stage of the development when the amount of API is limited. The purpose of this paper is to introduce a new method to measure real powder flow when the material is poorly flowing and the amount of material is about one to two grams.

The measuring method consists of a flow chamber and electronic balance and an automated optical detection system. The system has been tested extensively with various materials (pharmaceutical excipients, active drug powders, inhalation powders, and pharmaceutical granules). The determinations were made in normal laboratory environment (22 C and RH 46 – 63 %) using 1 to 2 grams of powder. The average relative standard deviation for the flow time determinations was 2 – 10 %, which is quite satisfactory. The potential applications for the developed method are for example API manufacturing and drug formulation research, especially powder inhalation optimization. The system can be easily be modified for various particle size ranges by changing the geometry of essential measuring chamber the potential measuring range being from few micrometers up to two mm.

In conclusion, the present novel flowability testing method provides a new tool for a rapid determination of flowing characteristics of powders and granules at a small scale.