Hausner ratio
The Hausner ratio is a number that is correlated to the flowability of a powder or granular material. It is named after the engineer Henry H. Hausner (1900–1995).[1][2]
The Hausner ratio is calculated by the formula
where is the freely settled bulk density of the powder, and is the tapped bulk density of the powder.[3] 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 [4][5][6][7][8] as an indication of the flowability of a powder.[9] A Hausner ratio greater than 1.25 - 1.4[10] is considered to be an indication of poor flowability. The Hausner ratio (H) is related to the Carr index (C), another indication of flowability, by the formula . Both the Hausner ratio and the Carr index are sometimes criticized, despite their relationships to flowability being established empirically, as not having 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.
References
General Bibliography
- ↑ Beddow, J. K. 1995. "Professor Dr. Henry H. Hausner, 1900–1995." Particle & Particle Systems Characterization 12: 213. Template:Doi.
- ↑ Podczeck, Fridun & Brian E. Jones, eds. 2007. Pharmaceutical Capsules. London: Pharmaceutical Press, p. 111.
- ↑ Template:Cite journal
- ↑ R.O. Grey and J.K. Beddow (1969) "On the Hausner Ratio and its relationship to some properties of metal powders" Powder Technology, Vol.2, No.6, pp 323-326.
- ↑ Q. Li et al. (2004) "Interparticle van der Waals force in powder flowability and compactibility" International Journal of Pharmaceutics, Vol.280, Iss.1-2, pp 77-93.
- ↑ C. Conesa et al. (2004) "Characterization of Flow Properties of Powder Coatings Used in the Automotive Industry" Kona, Vol.22, pp 94-106.
- ↑ S.L. Rough, D.I. Wilson and D.W. York (2005) "Effect of solids formulation on the manufacture of high shear mixer agglomerates" Adv. Powder Technol., Vol.16, pp 145-169.
- ↑ R.A. Garcia, R.A. Flores and C.E. Mazenko (2007) "Factors contributing to the poor bulk behavior of meat and bone meal and methods for improving these behaviors" Bioresource Technology, Vol.98, No.15, pp 2852-2858.
- ↑ USP <1174> "Excipient General Information Chapter: Powder Flow
- ↑ J. Cain (2002) "An alternative technique for determining ANSI/CEMA standard 550 flowability ratings for granular materials" Powder Hand. Proc, Vol.14, No.3, pp 218-220.