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Comparing the equivalent diameters of all the particles in a lactose powder, attributing them to consecutive size classes and finally counting the number of particles in each size class, results in the particle size distribution of the powder. Although the number of particles in various size classes can actually be counted, e.g. microscopically, it is seldom done because this method is very time- consuming and not very accurate.
A quicker and more reliable method to obtain the particle size distribution is to weigh the total amount of particles in each size class. The total weight (or mass) in each size class can be tabulated and graphically represented just as was done above for the number of particles per size class. Mass-based PSDs are frequently encountered.
Mass-based PSD of a sample of Lactochem Crystals
Size class
(u) |
Size class
number |
Grams
on sieve |
Mass
% |
0 - 45
45 - 75
75 - 106
106 - 150
150 - 250
250 - 425
> 425 |
1
2
3
4
5
6
7 |
1,84
3,68
7,07
7,49
4,24
0,32
0,04 |
7,5
14,9
28,5
30,4
17,2
1,3
0,2 |
Bar chart based on above table. |
