Ro-Tap method

Kostelnik and Beddow47 suggested and tested a Ro-Tap method for determining tap densities. They argued that, when measuring the tap density to be used in the Hausner ratio (see next section for its definition), its measurement should be consistent with the measurement of aerated bulk density in that it should use the same test cup. They considered the measuring cylinder as inappropriate because the visual determination of volume not only makes it difficult to determine the epd point but makes it impossible to determine the volume accurately enough. 

Kostelnik and Beddow Ro-Tap method A Ro-Tap method was used by Kostelnik and Beddow (1970) for tap bulk densities and they proposed that when the aerated bulk density was determined for subsequent use in the Hausner ratio (Section 1.4.1) the same standard test cup should be used. Visual determination of the volume end point is difficult and thus the weight end point methodology is preferable. 

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