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LADAL Pipette Centrifuge

The LADAL Pipette Centrifuge is an instrument for particle size measurement of sub-micron materials by sedimentation in the centrifugal field. Although experimentally very simple due to the use of a homogeneous start (as a direct analogue of the well-known Andreasen pipette method in the gravity field), the evaluation of data is complicated by the presence of the radial dilution effect and is, therefore, best done with a computer.

Principle of the Ladal pipette centrifuge

The program is based on the theory presented in the Instruction Manual for the centrifuge, a copy of which accompanies the software. Data entry is made by moving around a 'form' (with arrow keys) and typing in the data as appropriate. Some data, such as the centrifuge geometry and an example of experimental results are already entered in the program for guidance but any can be changed as required. It is also possible to load a set of data stored on disk, or to save data to disk for future use.

The experimental method requires gravimetric evaluation of solids concentrations in samples withdrawn from the rotating suspension at different times (in a 2:1 progression of time). The concentrations can be entered either as % by mass of the initial concentration at time zero or as the gross and net weights of beakers (including any dispersant) obtained in the experiment. Having entered the experimental data the user then moves the cursor down the display to view a table which contains the results. A log-probability plot of both the experimentally determined concentrations and the % undersize calculated by the program can also be viewed. The program allows the user to re-enter any of the data points to correct any errors or to bring any widely scattered points into line.

This is a highly interactive program developed by the original inventors of the Ladal Pipette Centrifuge over many years of industrial use of the instrument.