Hausner ratio

From Wikipedia, the free encyclopedia

The Hausner ratio is a number that is correlated to the flowability of a powder or granular material. It is calculated by the formula , where ρ_B is the freely settled bulk density of the powder, and ρ_T is the tapped bulk density of the powder. The Hausner ratio is not an absolute property of a material; its value can vary depending on the methodology used to determine it.

The Hausner ratio is used in a wide variety of industries as an indication of the flowability of a powder. A Hausner ratio greater than 1.25 is considered to be an indication of poor flowability. The Hausner ratio is related to the Carr index, another indication of flowability, by the formula H = 100 / (100 − C). Both the Hausner ratio and the Carr index are sometimes criticized because their relationships to flowability was established empirically and do not have a strong theoretical basis. Use of these measures persists, however, because the equipment required to perform the analysis is relatively cheap and the technique is easy to learn.

[edit] Reference

Mark Gibson (2001). Pharmaceutical Preformulation and Formulation: A Practical Guide from Candidate Drug Selection to Commercial Dosage Form. Boca Raton: CRC Press. ISBN 1-57491-120-1.