N

where:

N = efficiency in theoretical plates of the column under total reflux at this boilup rate (see Annex A1).

A2.8.3 Convert the boilup measurement in litres per hour to rates per hour in (mL/h) X cm2. Convert also the AP measurements to kPa/m (mm Hg/m) and the holdup measurement to millilitres per theoretical plate.

A2.8.4 Plot all data as ordinates versus boilup rate in litres per hour and (mL/h) X cm2 as abscissa. Draw smooth curves through the points for holdup in millilitres and in millilitres per theoretical plate. The boilup versus AP measurements should be compared with those made in the efficiency measurements if available, to ensure that they are in reasonable agreement.

A2.8.5 Draw a vertical line at 75 % of maximum boilup rate. The dynamic holdup for the column will be that read from the intersection of the holdup curve and the line for 75 % of maximum boilup rate. The charge size, ranging from a holdup ratio from 2 to 4 % will thus be from 50 to 25 times the above figure.

A2.9 Precision and Bias

A2.9.1 No statement is made concerning either the precision or bias of Annex A2 for measuring dynamic holdup because the result is used to determine whether there is conformance to the criteria stated in Test Method D 2892.

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