Sieve Diameter

Sieve diameter is the equivalent spherical diameter assigned to a particle based on the mesh aperture it passes or is retained on during sieve analysis. Because real particles are irregular, sieve diameter is method‑dependent and differs from optical or volume‑based diameters measured by laser diffraction or image analysis. For filtration, sieve diameters in the coarse range (often >38–63 µm depending on the sieve stack) anchor the upper tail of the PSD that dominates cake permeability and early pressure‑drop behaviour. Reliable sieve analysis requires representative sampling, appropriate wet or dry techniques to prevent agglomeration, and calibrated sieve stacks maintained to avoid aperture drift. When correlating to filter performance, combine sieve‑derived coarse fractions with fine‑fraction methods so that media selection (aperture/MFPS) reflects the full PSD actually reaching the filter after pumps and mixers.