Carrs percentage compressibility from bulk densities

2 Carr s percentage compressibility from bulk densities 

Although the Hausner ratio or FR is a reliable indicator for the prediction of the flowability of powders the ratio may not represent the actual compaction behaviour a powder may 

Compressibilities in excess of 20% tend to create particle bridges in hoppers while powders with a compressibility percentage greater than 40% are difficult to discharge (Table 1.6). At present the Hausner ratio is used more widely than compressibility, although Carr (1965c) used his parameter extensively to classify various types of powder into categories of excellent or very poor flow. The Carr approach to flow has now been subsumed into a standard test method for bulk solid flowability (ASTM D 6393-99 1999). 

The Carr s compressibility percentages have been effectively correlated to measure  

Flow ratio 1.28 1.28 flow ratio 1.57 Flow ratio 1.57 

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