Pharmaceutical Clients Clamoring For WWII-era Average Particle Diameter Testing

The Model 95 Fisher Sub-Sieve Sizer is an odd sight in PTL's collection of state of the art, computerized particle testing equipment. Built on a particle testing technique dating at least to the 1940s, the instrument's wood housing, rubber tubing and analog manometer for fluid pressure measurement may inspire more nostalgia than technical confidence at first glance.

But lately, it seems the pharmaceutical industry can't get enough of this classic particle testing technique. PTL clients are increasingly requesting testing via FSSS per current ASTM, ISO and USP methods. The Sub-Sieve Sizer tests powders quickly and reproducibly for their Average Particle Diameter - also known as the Air Permeability Diameter.

The analytical technique determines the average particle size by measuring the pressure drop across a packed powder bed using a water manometer. The pressure drop is a function of the permeability of the packed bed. This is related to the surface area of the particles which is then transformed to an "average size" based upon the assumption that the particles are spherical. The disadvantage of the technique is that it does not report on the statistics of the size distribution.

PTL's philosophy is to provide as many lab options as the client needs, and that ensures that the best techniques - modern and classical ones such as the Fisher Sub-Sieve Sizer alike - are readily available to provide insight into client projects.

Main Menu

Our Services

Particle Size Distribution Analyses - Sieve Analyses Sieving has been around since the time of the Egyptians and can be considered the backbone of particle size technology. Sieving’s continuing popularity is due to the technique’s fundamentally...
Microscopy Services Image Analysis Automated Image Analysis offers particle size distribution as well as shape. Other parameters measured are Circle Equivalent Diameter, Length, Width, Perimeter, Area, Aspect...
Powder Flowability Freeman FT4 Powder Rheometer The flowability characteristic of a powder is directly related to both the physical properties of the material itself, as well as the specific processing conditions in...
Surface Area & Pore Size Analysis - B.E.T. Specific Surface Area Micromeritics Flowsorb II 2300 (Dynamic Flow Technique) Micromeritics TriStar 3000 (Static Pressure / Volumetric Technique) Quantachrome Autosorb 3B (Static Pressure / Volumetric Technique) 1...
Particle Size Distribution Analyses - Electrozone Coulter Counter Technique Electric Sensing Zone is also referred to as the Coulter Technique or Coulter Counter. The instrument is a true high resolution, high speed particle counter and particle...
Surface Area & Pore Size Analyses - Mercury Intrusion Porosimetry Mercury porosimetry is a powerful technique utilized for the evaluation of porosity, pore size distribution, and pore volume (among others) to characterize a wide variety of solid and powder materials....
Surface Area & Pore Size Analyses - Pore Size Distribution & Structure (Nitrogen Gas Physisorption) Includes B.E.T. Micromeritics TriStar 3000 (Static Pressure / Volumetric Technique) Click here for a typical sample report Pore diameter range ~7 - 4000 angstroms (0.0007 - 0.4 microns) 10 – Point Adsorption...
Particle Size Distribution Analyses - Particle Size and Shape Analysis Image Analysis is a powerful analytical technique which can provide additional information on a sample compared to just “particle size” and distribution. The majority of particle sizing...