Tapped bulk density

The bulk density of a powder is calculated by dividing its mass by the volume occupied by the powder (Abdullah Geldart, 1999). Tapped bulk density, or simply tapped density, is the maximum packing density of a powder achieved under the influence of well-defined, externally applied forces (Oliveira et al., 2010). Because the volume includes the spaces between particles as well as the envelope volumes of the particles themselves, the bulk and tapped density of a powder are highly dependent on how the particles are packed. This fact is related to the morphology of its particles and such parameters are able to predict the powder flow properties and its compressibility. 

The loose bulk density of indinavir sulfate is typically 0.2 g/cc, while the tapped bulk density is typically 0.2 and 0.4 g/cc [8]. 

Powder flow requirements vary with equipment design. To maintain a low weight variation, optimum values of Carr s index (CI) is in the 25 to 35 range for Zanasi and 18 < CI < 30 for H K. Note Carr s Index is calculated from the loose bulk density (LED) and tapped bulk density (TED) of powders. CI = 100[(TED LED)/TED]... 

Common indices of flowability are the Hausner ratio and the Can index (compressibility). The increase in bulk density of a powder is related to the cohesiveness of a powder. So measurement of the bulk density of a powder is essential to define the flow characteristics. Ratios of poured-to-tapped bulk densities are expressed in two ways to give indices of flowability ... 

Tablet properties inputs) Dose (mg) Solubility Particle size (gm) Minimum bulk density (g mU ) Tapped bulk density (g mU ) Carr s compressibility (%) Formulation 50.0 Insoluble 5.0 0.4 0.7 42.857 ...

Carr " reported that the more a material is compacted in a compaction or tap bulk density test, the poorer its flow properties. He defines compressibility C by... 

A comparison of true particle density, apparent particle density, and bulk density can provide information on total porosity, interparticle porosity, and intraparticle porosity. Methods include true particle density measurements via helium pycnometry, mercury intrusion porosimetry, and poured and tapped bulk density. 

Tapped bulk density Apparent density Average grain size ... 

In spite of low tapped bulk density, apparent density of FRP powder is not low compared with silica sand. Therefore FRP powder itself can not make BD of hydrated composite much lighter. 

Tapped bulk density is, in theory, the maximum bulk density that can be achieved without deformation of the particles. In practise, it is generally unrealistic to attain this theoretical tapped bulk density, and a lower value obtained after tapping the sample in a standard manner is used. 

The increase in bulk density of a powder is related to the cohesivity of a powder. Ratios of the poured to tapped bulk densities are expressed in two ways to give indices of flowability. 

A powder in a container subjected to a low compressive force will undergo particle rearrangement until it attains its tapped bulk density. Ultimately, a condition is reached where further densification is not possible without particle deformation. If, at this point, the powder... 

The molding powders have a tapped bulk density of at least 0.2 g/cm. Tapped density is measured by placing a weighed quantity of sample in a graduated cylinder, and tapping the cylinder until the volume is essentially constant. If the bulk density is less than this minimum, it will be found that the powders are extremely diflicult to compact uniformly, and will give compacts having internal strains and in which stratification of the solids will be present. 

Tapped bulk density is defined by ISO as the mass per unit volume of a material tipped into a container and... 

In selecting wollastonite as the functional filler for plastics, most of the properties to be considered are white color, high brightness, moderate specific gravity, moderate Mohs hardness, moderate range of loose and tapped bulk densities, needle-like particle shape, high processing melt temperature, wide compatibility with silane and titanate surface treatments, and low CLTE. 

One of the standard methods to evaluate the flowability of a particulate system is to calculate the Hausner ratio after tapping. The Hausner ratio is defined as the ratio of a powder system s initial (loose) bulk density to its tapped bulk density (i.e., the ratio of loose volume to tapped volume). It is easy to calculate the Hausner ratio and evaluate the flowability when the loose and tapped volumes of the test material are known. For a Hausner ratio of l.O-l.l, the powder is classified as free flowing 1.1-1.25, medium flowing 1.25-1.4, difficult flowing and >1.4, very difficult flowing (Hayes, 1987). 

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