What is Air-Permeability
What is Air-permeability Particle Sizing?
The SAS reports particle sizes in the range 0.2 to 75 micron and does this based on the pressure drop across a packed bed of powder. By varying the Sample Height the density (described as "porosity") of the bed the average Surface Area and hence Particle Size can be determined as a function of Pressure drop in accordance with the Carmen equation.
In the simplest terms, the pressure drop across the bed increases with increasing Surface Area (and decreasing particle size).
Why Air-permeability Particle Sizing?
Air-permeability techniques generate average Specific Surface Area (SSA) data for a sample of powder.
The SSA of particles has a significant impact on the physical properties of powders and has been the focus of much attention from such diverse communities as the pharmaceutical, paint, toner and geologic professions. The SAS has particular applicability to the Pharmaceutical Quality Control field where the quick and reproducible SAS-derived Surface Areas can be used to control batch-to-batch variation in important properties such as bioavailability and drug delivery.