Homogeneous cumulative gravitational sedimentation

The principle of this method is the determination of the rate at which particles settle out of a homogeneous suspension. This may be done by extracting the sediment and weighing it allowing the sediment to fall on to a balance pan or determining the weight of powder still in suspension by using a manometer or pressure transducer. 

One problem associated with this technique is that the sediment consists both of oversize (greater than Stokes diameter) and undersize particles so that the sedimentation curve of amount settled P) against time (r) has to be differentiated to yield the weight (W) larger than Stokes diameter. Several balance systems, based on this equation, have been deseribed. 

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Homogeneous Suspension Method. Equation 38 still applies however, at time t, all particles of size greater than Dp(t) will have settled out radially to a distance Rr2. Conversion of the sedimentation curve into a cumulative curve is not as simple in this case as for gravitational sedimentation. Difficulties involved in evaluating the sedimentation curve in centrifugal fields may be overcome by assuming a constant... 

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